After over a year of working with these systems, I have refined my recommendation on equipment and build a little.
IMPORTANT
Before reading further, the design in this article does not meet new requirements I have learned about the BP220, During the design of this 2 years ago, there was no information about reverse charging with the BP. We got away with it for a long time but this could be a fire hazard, READ MORE HERE.
I will most likely be replacing mine with a relay.
While our original Tesla battery install is working great I have had the opportunity to install a few more of these systems and get tons of questions about it.
These systems can be constructed with numerous different components and can work with many different designs, however to keep costs down and make a safe system the following is a recommendation on one way to build a safe, cost effective Tesla Install.
Do note that while Tesla batteries are a very high quality and safe when handled and run within operating characteristics, if something goes wrong they can be quite dangerous. It is your responsibility to fully understand and make sure the system is safely programmed and installed if you choose to take on an install like this.
Furthermore, this build is not endorsed or supported by any manufacturers of the compenents used in this build, and they may not provide support on an install like this if you run into trouble.
I also am not able to provide individual support on these builds. You might be able to find community support over in the Second-Life Batteries Facebook Group.
Here is a list of parts and components
Recommended Changes from the Original System
The following is an update to the way I originally installed my battery. This is not necessarily the best install option, but it is cost-effective. This install does not utilize a full-time BMS but if you are interested in using one Batrium is coming out with a new watchmon 5 (or watchmon plus) and should be a great solution for integrating Tesla packs with a full supervisory BMS solution at a cost-effective price. You can learn more about the Batrium BMS here.
The main component changes in my system involve the exterior voltage and temperature monitoring to control battery shutdown. The Victron BMV 712 was not available when I built my system, but is a far superior product to the BMV 702. This device has the capability to control an external relay on temperature, high voltage and low voltage. It can do even more, but these three features simplify the install if we use it to control the battery disconnect. The below schematic shows how I recommend using this as the primary disconnecting means for battery charging.
The intent of operation of this install is to have the Inverter and charge controllers be programmed to not overcharge the battery. I usually program the absorb and float to 24.00V and 23.98V or 24.5V and 24.48V respectively. I use the 24 V setting for general usage, but in the dead of winter I push it a little to 24.5 to get a bit more power out of it for cloudy days and long nights . These settings will appropriately charge the battery, but in the case that something went wrong with the chargers or the settings got changed we need a backup to prevent overcharging the battery (one of the most dangerous conditions) That is where the BP220 input disconnect is used with the relays from the BMV712 to take the battery offline. I program the BMV712 high voltage relay setting to 24.8V
The battery temperature should also be managed externally and can be done with a heating pad and a controller or I have seen some have success using these tank heating pads.
These devices should keep the battery warm, but in the case that the battery is too cold it should not be charged and thus the relay in the BMV again can be set to switch on temp. I set the low temp switch to 42 degrees (because at that temp something is wrong with my system) but you can use whatever you feel is safe for your setup. The BMV712 has a temperature sensing option that is connected off the shunt and sends temp info back to the head unit.
The only trouble with using the BMV712 relay to disable charging is that you actually need two relays for this system as the inverter charge can be disabled using one of the inputs. ( you need to program the inverter to use an input as a charge disable, for victron this is done with a external BMS assistant). To get two inputs from the one relay output on the BMV712 we use a DPST relay and hold the coil closed. This is a fail safe configuration that will open and shut down charging in a failed state.
Of course when commissioning a system like this be sure to test the system by setting temps and voltages too low and letting the BMV disconnect the system to make sure everything is working properly.
The rest of the system is pretty similar to how I have it drawn out in the previous posts. You can connect the AC side from the inverter however you want but if you are connecting to a 50A 240V split phase RV a new product that might assist your install is the AM solar smart ATS. This allows you to use a hybrid inverter automatically on a 50A system. The only drawback to this is if you have a built in dual leg single phase generator as it will half the power output from the gen. I have talked with them about this and they may fix it in future versions.
List of Components
For those looking for a list of components, here it is:
Again this is not complete and you can swap components for your system, but this is what I have used.
Component Description | Model | Source |
Inverter | Victron Multiplus 24/3000/70 |
Solar Charger option 1 | Victron Energy MPPT 100/50 SmartSolar* |
*This charger will limit the system to 1400W |
Solar Charger option 2 | Victron Energy MPPT 250/100 SmartSolar* |
*This charger will be good for solar up to 2800W |
Battery Monitor | Victron BMV 712 |
Temp Sensor | BMV702/712 Temperature Sensor |
Under/over-voltage disconnect (2) | Victron BP220 |
Main Battery Disconnect | Blue Sea 6006 Mini Disconnect |
Bus Bars (2) | Blue Sea Systems BusBars (100A-250A) |
I recommend the use of busbars, they help keep installations clean and distribute power well |
24V-12V Converter | Victron Energy Orion 24/12-40 DC-DC |
*If needed can get the 70A version that has lugs and is adjustable voltage |
Battery Meter / Balancer | Tenergy 5-1* |
*This is not used as a “BMS” just to periodically check and balance the batteries, You need to adapt XH connectors to the battery cells to use this device. Do not leave this plugged in as it will unbalance the battery. |
Battery Terminal Fuse holder (2) | Blue Sea 5191* |
*These are optional but provide extra protection for the batteries during installation and handling from a short |
Battery Terminal Fuses (3) | Blue Sea 5189* |
*These are installed at battery on lugs. If battery is shorted this will protect battery internal fuses from destroying battery |
Main Fuse | Class T 200A |
Main Fuse class T holder | Class T fuse holder |
Solar Fuse and holder | 60A ANL holder and Fuse |
Inline Fuse for relay | 2A inline fuse of any type |
DPST Relay 24V* | DPDT or DPST relay @24V coil (down to 18V) |
*This is just a relay that turns one signal into two… we cannot put the two devices in series due to how their circuits work. |
60A inline Breaker for Solar | DC – 60A 24V breaker |
1/0 Cable | However much you think you need |
just a suggestion. Make sure its true 1/0AWG, not international wire standard |
6AWG cable | Combiner – charge controller- busbar wire |
1/0 Lugs | you need a minimum of 16 |
Battery Heater Pad | Water Tank Heating Pad |
I have heard of people having good luck using these tank heaters. |
Solar Combiner Box | (recommendation) |
As in the previous posts this system does not utilize a full BMS but rather relys on periodic testing of the battery to check balance with a tenergy 5-1 cell meter. To use one of these with a tesla pack you need to either buy a pack that has standard JST-XH connectors adapted to it already or you will need to adapt it yourself.
Dave posted a comment on my prevous post about having to adapt his battery to work with the tenergy 5-1. Below is his recommendation and it sounds about right.
If you received your Tesla Battery with the BMS Board still attached, I recommend you immediately remove it. My BMS Board was “electrically” warm when I received my Tesla Module.
-Dave
The Tesla BMS wires on the Module are numbered 0 to 6, with 0 and even numbers on the top and the odd numbers on the bottom. the 0 wire is attached to the negative terminal of the battery and 1 – 6 address the different cells. Electrically, each BMS wire is additive, i.e.: between 0 and 1 is 3.5v and between 0 and 2 is 7v and 0 – 3 is 10.5v, etc. (your voltages will vary). The Tesla BMS uses two JST XH connectors, one is a 5 pin connector and the other is a 7 pin connector. I purchased a set of JST XH extension cables from Amazon, the set consisted of 2 cables each with 3, 4, 5, 6, and 7 wires. I took a 7 wire connector and a 5 wire connector and removed the male ends from each connector, I then inserted the pins from the two female connectors in a 0 – 6 sequence into the male connector. The two female connectors were attached to the two BMS leads from the Tesla Battery Module, the key to sequencing the female connectors is that Tesla used every other pin on these two connectors. So, what you wind up with is: Male pins 0 – 6 as follows: (# 1 pin top) then (# 1 pin bottom) then (# 3 pin top) then (# 3 pin bottom) then (# 5 pin top) then (# 5 pin bottom) then (# 7 pin top). The male 7- pin connector then fits right into the Tenergy BMS.
You can also purchase these packs already modified from Jason Hughes at 057 tech. Jason is also working on a simple BMS solution that will balance the packs and possibly have an alarm output. It is not available yet but conceptual drawings are out and it looks great! Keep an eye out for it at https://057tech.com/
If you are considering using Tesla packs in a mobile application I hope this helps you out and gives you an idea of one way to do it. If you want to learn more about this and other systems be sure to join us on our Second Life EV Facebook Group!
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Much appreciated Tom! Thank you so much for the time you put in to help the rest of us out.
I got huge issue if someone could help ? My 4 module s tesla stay at 23.8 wont go any higher on my controller is set to 24.4 and float 24.2. When i turn on the inventer it shutoff 🤷🏽♂️
You don’t give us much to go on. What type of inverter, charger, solar, solar charge controller, what device is charging the batteries and from what source. All that would be a big help in suggesting solutions.
Nolo… It is possible you don’t have enough charging power @24 volts to charge the 4 Tesla Modules. I would disconnect three of the modules and try charging only a single Module, then add one Module at a time and test my results. It is also possible that one Module is not able to properly charge so you might have to test the system with a different “Single” Module to eliminate that issue as a possibility.
PS: next time you post a “New” issue like this one please post it at the end of the postings so we can more easily find it to respond, with this forum format it is not easy to find postings so we can all respond.
Well i addes balancer to all of them . Battery came unbalance from ebay seller 😕 . Thank god my gut never fail i would have mess up all 4 packs
Thanks david i did what you say i charged one by one all 4 charge now system is working
The Victron BMV 712 easily networks with the Victron smart solar charge controllers and are combined in one bluetooth app 🙂
When Tom speaks of “inverter charge”, he’s referring to a Victron inverter with a built in 120VAC charger, not a stand alone inverter.
Thank you for clarifying, Yes that is referencing an inverter charger, specifically the Victron 24V multiplus I used.
Awesome update! You have a typo, I believe: “I usually program the absorb and float to 24.5V and 23.98V or 24.5V and 24.48V respectively.” That should be: “I usually program the absorb and float to 24V and 23.98V or 24.5V and 24.48V respectively.”
Thank you for this catch, Has been updated.
Tom,
I am using the same 24/3000 inverter and I have read you lower the float charge by 0.02 volts from the bulk charge. Did you adjust or reconfigure the bulk/boost charge time under the charge profile software? Do you set your MPPT charge profile to match the inverter profile? Can you send me a screen shot of your charge profile from the Victron software?
Out of curiosity, why did you move to the BP220 after the solar charge controller from the BP65?
I read the fine print: “The solar disconnect BP unit is oversized for future alternator charger” 🙂
Does anybody know what the safe charging characteristics for a 48V system would be? Do I just double the 24V system safe charging higher up in the comments, or are they different? I need to set up a 48V system running an 8000W hybrid inverter/charger from victron. I am going to be using all Victron products as they all have the manual setting functionality. I already have 4 of the tesla batteries.
Thanks for any help.
Double the 24V setting for 48V
Curious about this, I was wondering about 2 Series Tesla Units for 48V, three in Parallel
What do you put in the BMV-712 in terms of capacity? The Tesla battery has about 530 AH of capacity when charged to 25.2V. If only charging to 24, do you have it show 100% or 90% charged?
Thanks
Correction. 233 Ah Capacity at 25.2V
I set the BMV-712 to 24.9 for fully charged. In my Multiplus I have the inverter shut off at 19.6v and I have the BP-220 shut of at 19.6v
Any ideas for improvements?
Linc
Can you tell me what software you use to create the wiring diagrams?
The program is called Draw.io
I have my BP-220 and Multiplus set to shut off loads at 19.6. During testing I get a Multiplus low battery alarm and system shutdown at 20.6V I can’t figure out how to get it to use that last one volt!!! Any ideas?
Both your videos and schematics have proven invaluable to my venture into adding solar to my trailer. Though I haven’t started the install most of the equipment has been taken from your design. It is a most elegant design and thanks for making us aware of 057 Technologies, they were most helpful.
Tom, Am I correct in assuming that if I am tying into a 30 Amp load and use a Victron Energy DMC000200010R Digital Multi Control 200/200A GX to turn on the inverter on and off remotely that I don’t need a manual transfer switch? I think all I have to do is tie into the AC fuse box and run a line back from the disconnected shore power to the inverter / charger. At least I think that right.
Richard Gale, If you are using the Victron 24/3000/70 Inverter (as listed above) you don’t need to worry about switching the inverter, either on or off, whenever you plug into shore power. Because, the Victron has a built-in automatic transfer switch which takes care of that issue. Simply put, whenever the Victron senses Shore Power the transfer switch automatically cuts the power from the inverter and allows shore power to feed your breaker box, similarly, whenever the Victron senses the loss of Shore power the Inverter automatically kicks in. Additionally, whenever the Inverter senses Shore Power, the inverter switches over to “Charge Mode”. As far as wiring a 30 amp system, you simply wire the inverter into the middle of your shore power supply wiring, in other words, the circuit looks like this… Shore Power connection to Inverter (A/C in) — Inverter (A/C out) — to your breaker box.
Thanks David the clarification was very helpful and the rapid reply is much appreciated
Tom,
I noticed on you diagram there no frame ground. I’m looking at doing something similar to the Drivin and Vibin setup. As a matter of fact I bought the kit from Battle Born to do just that.
What I’m not clear about is how big my grounds to the frame need to be. I’m also using 2×1/0 because that’s the biggest die I have for my hydraulic crimper. Do I also need to run a 2×1/0 to the frame from the negative bus bar?
Hi Eric, did you ever figure this out. I’m currently wondering the same thing.
These videos and posts are great and now part of our planned Insect Monitoring Station to study pollinating insect populations. I haven’t seen mention of the RFI profile from the Victron and other equipment. We use sensitive HF and VHF devices to listen to instrumented bug habitats. Has there been good, low noise experience with this particular solar configuration? It’s crucial and I haven’t been able to get much info from Victron.
I am putting together a solar array and Tesla 5.3 Kw battery. i have a victron 220 battery protect between the battery and the 5kw LF PSW inverter with a built in 80 amp charger. I can plug in from the grid or a generator to power a small travel trailer.
Will the victron protect the Tesla battery from current coming out of the charge section of the inverter. I Am also unsure if the voltage out of the charge section is compatible with the Tesla. The inverter charge cut off is around 28 volts so I want to limit that somehow, or not use it for charging off of the grid or inverter generator. Will the battery protect work in reverse?
Thanks for your videos.
DCF
David Floyd… You are correct in that the BP 220 is directional. However, in your setup, unless you can control the charging voltage from your Inverter/Charger the voltages will be wrong for the Tesla Battery. Additionally, even though your charging amperage is 80 amps, you might want to reduce the charging amperage to around 50 (if you can actually set the charging voltages lower for the Tesla Battery) to reduce the size requirements for your wiring. You would control the direction of the energy flow by reversing the “battery / Load” connections and using the on/off loop on the BP 220 with a switch or relay circuit.
Thanks –Very Much! I am new to this and I have some help from a couple of electronics guys, but I want to employ as much of my grey matter as I can. I intend to use a small 1000w Sportsman inverter, PSW generator for charging and my thought was that if I ran it into the inverter it should come out at 24v DC and low amps. That should be ok for the tesla. Apparently, the grid current is too much without some modification. I do not think I can set the charge parameters on this particular inverter. My thought was that the inverter charge output should be 24 volts since it is a 24 volt inverter. Again, I am “grasshopper”. I am waiting on the reply from the engineer regarding output specs on the charge section. I know the cut off is at about 28 volts which is out of the question in any case.
I may have more questions when I absorb this part, if you can bear with me. I am getting input from everybody I trust, but I am hesitant to risk a $1300 battery.
Thanks,
DCF
Just finished a 900 mile road trip. One stop was to pick up a tesla battery. He had a stack of them.
He drives a tesla, his home is served by a small bank of “S” batteries and his mobile install is a Landrover/camper ( a little understated) with a 4-pack of “S” batteries.
I am pretty sure his experience is noteworthy.
He gave me some tips on configurations and practical solutions. I am about to put my particular application together, so I hope I can count on your input. Maybe,I can keep from screwing up a big pile of cash.
Thanks,
DCF
On the positive of the battery line what if any advantage is the 200A fuse and the battery cutoff switch over a 200A circuit breaker that also acts as a cutoff switch?
Tom Just finished watching your series on lithium battery install. I am an EE and have been studying peoples battery installs. Great job of covering the charging and safety concerns with the system. Well presented videos. Only concern is using green wires to run AC lines. Yes you know they are AC but what about the next guy who has to service the system?
Great travels
Bruce
I have been exchanging comments regarding the battery protect with Victron. I think this may apply to one of your BP220. This is the exchange.
Initial question was about protecting both a battery and charger.
“mvader (Victron Energy Staff also CEO of the company) answered · Feb 19 at 4:52 AM · ACCEPTED ANSWER
Hi, here the official answer:
The BatteryProtect is not at all designed in a way that the current can flow both ways.
Doing so might result in fire. Do not do it.
don · 2 days ago
Not to dispute the official answer, but what about a battery connected to an inverter/charger. When inverting, the current is flowing from the battery to the inverter and in charging, the current is flowing form the charger to the battery. If there is a battery protect in the circuit, isn’t the current flowing both ways?
mvader (Victron Energy Staff) ♦♦ don · 2 days ago
Hi @don, indeed its flowing both ways. Its why a BatteryProtect should never be placed there in the circuit.”
I think this applies to your BP220 that comes off the battery.
I had never heard of that limitation of the battery protect and it certainly limits its usefulness.
Don
Thanks Don,
that is a very important information. Changed my wire setup now. I’m happy nothing happend till now. I have 2 100A BP. One for the load disconnect and one for chargers. The charger was connected to the “OUT” terminal of the load BP. I changed that to the “IN” terminal.
What really bugs me is that there is no information about this issue in any documentation.
Don, I actually just read that thread on the Victron Forum. So did you move the BP220 to be between the MultiPlus and the positive bus bar? Which would limit it to only protecting for low temperature charging. What would we use to safeguard against the DC system pulling the battery down below acceptable levels?
According to my reading of the Victron thread, you can not put the BP between the battery and the charger since current will flow in both directions. You can put the BP between the battery and the inverter. In this case the BP could protect against low and high voltage in the battery. However, the high voltage is fixed and is way over what a Tesla battery will take.And my inverter is limited to 40 volts( a 48 volt inverter), which is higher than it needs to be for the Tesla. So, I just took to BP out of the system. If you are using a different battery, then the high/low voltage protection could be valuable. Just not in my (Tesla) case.
Tom,
Thanks for your well written article along with a list of components. I am going to embark on two projects utilizing Tesla battery modules. One for home backup ower and time shifting and the second for a aprinter RV power system. Both projects will likely use Victron components due to their programability and hopefully full compatibility with 6S modules which presents issues with low voltage cutoff default values in most inverters that are designed for lead acid systems.
Have you been able to program the multiplus 2 to allow for battery usage down to 19.8 volts (3.3 volts per cell) without sounding the low voltage alarm or inverter automatically shutting down? This has been an issue for most other inverters which at default settings would limit usage of the Tesla modules.
I am convinced that the Tesla batteries are best for many applications, except for the 6S limitations that currently exist as we shift from lead acid to lithium (with the exception of LiFepO4 batteries which at this time are very expensive per KWH)
I have designed and built a similar system (essentially copying Toms) using the same inverter, but am having the same issue with the the low voltage cutoff. Please help!
Steve and Don…
I just checked my Multi Plus Inverter/Charger Owners Manual and in the Appendix, section 8, Technical Specifications; it lists the Inverter’s Operating Voltage as 19 to 33 volts.
Have you tried programming your Inverter with a Computer to set the operating Voltage? The other thing you might want to investigate is the operating voltages of the various battery types listed for the Dip Switch Settings, maybe changing those settings will allow the Inverter to operate below your 19.8 volts you have been experiencing.
Please let us know what you find out because we all will be facing this issue soon.
PS: It seems odd that the BP module will shut off the flow of electrons out of the battery at 19 volts while the Inverter would shut itself off sooner than the BB module at 19.8 volts.
Hi all, its Don Bisbee again with an update.
I based my system on Tom’s design using a Tesla Model S battery module along with the 24/3000/70 Victron Multi Plus. I have a few thousand dollars and about nine months of design and build time into it. I saw some of the low voltage issues before I pulled the trigger and headed down the slope, but according to Victron all parameters are adjustable, not to mention Tom has a working system that he has some very high quality YouTubes posted explaining it. Since I once was a research electrical/mechanical tech with Boeing for 15 years and a Navigation Electronic Tech on a nuclear sub I felt confident I could carry this off.
Today I established full communications with my system (24/3000/70, 100/20 MPPT, BMV 712, and a Venus GX), but I found that there are very few parameters that are adjustable. My system started with the Low-Voltage LED on, but I was able to charge it slowly with my solar (I can only get about 25-70W on a good day here in the NW, though I have seen 160W briefly on my 2 265W panels) then I hooked up the generator to the Multi and it charged at 50+ amps for a couple of hours until I cut it off at 25 V. Low Volt LED still on, but blinking. I restored defaults and now it is steady on but will not charge (it is down to 23V as I use it to power my BMS through 2 back to back BP220’s).
I think it is possible that this is a different issue with similar symptoms, since the battery voltage is well above the minimum 20.8; and I have posted the question on the Victron Community website.
I found a thread today on the Victron Community site (among many many others…)by someone who is apparently the CEO of Victron as attested to on other threads: https://community.victronenergy.com/questions/5217/tesla-model-s-battery-multiplus-can-not-turn-on-in.html, is what he said about the issue (after several months of posts about how Victron was working on a fix):
mvader (Victron Energy Staff) answered · Apr 06 at 12:35 AM · ACCEPTED ANSWER
Hello all,
So we looked at changing the logic and changing the values.
And for the near future there will be no changes. The main problem is that some models need a higher DC voltage to start up; than they need to stay running. And there are more small and large issues that make going in and changing some of these logic & parameters a mine field that requires a too significant time investment than we can make now.
Sorry, but that is what it is now. I understand how nice it is to be able to use these tesla packs that have slightly low voltage; but will not make it better now.
The related topic as discussed in these threads: yes we added shutdown on low SOC some time ago. See VE.Bus firmware change log. However that does not lower any DC voltage shutdown limits. see also below screenshot.
Thanks all for all the effort and input!
Best regards, Matthijs
Personally, I don’t buy it; I doubt there is a technical reason why they could not add a default battery selection a profile for one, but there are probably a few other ones.
But the word from the top is clear: this inverter has not ever and will not ever work with a 6S battery (i.e. Tesla Model S).
What is really needed (if Victron is unwilling to put into its battery selection a profile for one) is a 2S74P module that could be placed in series for each module.
So, my question is: Is this whole Tesla battery/24/3000/70 Multiplus a hoax? Has anyone actually made this work? If so, I would greatly appreciate a share of how.
BTW, this is not specific to Victron products, Xantrex and Magnum have the same issue.
Could you post a schematic of your setup. It may be the BP 220s. They are not supposed to be used when the current flows in both directions.
Its not so easy to post a schematic; I don’t have that drawing software package that Tom has. But the 2 BP220’s are hooked up source to drain between the battery + and the 24/3000 (which is a significant departure from Toms system). I pickoff some after the BP’s to run the voltage and temp sensor relays and it doesn’t work when there is no supply to them so there is proof in the concept, but I bet there is a voltage drop across them both and it could be 3 v or more. The more I think about that, the more I think that the voltage drop across them both has got to be it, I will have to see if there are any specs that provide the drop, but we used to figure about 1.5V. I will test it with a big jumper next chance I get and get back to you, but it may be a day or two. Thanks for the suggestion Don, sorry for flack you all; been a frustrating few days!
Don, I’m so curious what outcome you reached. Please advise, as the footsteps I follow are seeming more and more foolish…
I have not been able to find the exact type and configuration of mosfets used in the Victron BP. Has anyone found a detailed description? Also looking around I found this application example(s) of a mosfet battery protection circuit and discussion of bidirectional operation.https://electronics.stackexchange.com/questions/277248/lithium-battery-protection-circuit-why-are-there-two-mosfets-in-series-revers
Two of the recent comments, one by DonCobb and the other by Don Bisbee, really SUCK !!! I am, of course, referring to the comment by DonCobb in which he references comments made by the Victron CEO in which he states that the BP modules were never designed to handle bi-directional energy flow. I am also referring to the comment by Don Bisbee in which he had discussions with Victron regarding an issue where the Inverter will not operate below 19.8 volts (referencing Steve Fong’s post).
The answers received from Victron really suck for those of us trying to implement a system using a Tesla Battery Module based system.
So, here is how I worked around DonCobb’s information regarding bi-directional energy flow… I moved my BP220 module away from the battery and placed it after my 24v bus-bar. The BP220 is now connected in-line with only the DC/DC Converter to protect the battery from being drained below 19 volts by the 12 volt systems on the Coach. The inverter will not operate at voltages below 19.8 (ref. Steve Fong above) so we don’t have to worry about the inverter draining the battery and the Inverter can charge the battery directly via the 24v bus-bar. I still have a BP220 placed in reverse orientation in-line with the Solar Charge Controller to protect the battery from being charged whenever the battery is too cold, too hot, or overheated (based on a closed loop, thermal monitoring, system described in previous posts).
Don Bisbee’s post regarding operation of the Inverter is very, very, troubling. Apparently, Don’s Inverter won’t work at all at 25 volts, this really, really sucks and the issue seems closed with Victron, this sucks even more. While Steve Fong’s Inverter works just fine until he reaches 19.8 volts and the Inverter shuts itself off.
I mulled over the Inverter shutdown issue and have decided that in my situation, powering my RV for Boondocking, having the Inverter shut down prematurely (at 19.8 volts) is not that big of a deal because the coach runs just fine with it’s 12 volt systems and having Propane available for heating and cooking. Now, the previous sentence is predicated on my Victron Multiplus being able to operate at voltages above 19.8 volts. I am sitting here on the cusp of installing my system and am hopeful that I purchased my Multiplus early enough that it will work down to 19.8 volts. If this is the case, then not having the Inverter available below 19.8 volts will not effect me very much and I can Boondock all I want to with my Coach.
Several people have installed these systems, based on Tom’s design, and the issue of low-voltage operation has only recently been mentioned. So, I hope this only effects the newer Victron Multiplus Inverters (especially those newer than mine). In Tom’s case, his Inverter was 5 years old when he did his installation, and that was a couple of years ago now, so, it appears he is not effected at all.
Hi All,
Don Bisbee again with a quick update. My wife finally retired and we are trying to head out on our next great adventure next week, so I don’t have time to get everything ironed out the best way. Today I pulled out our 12V AGM house batteries and hooked them up to the inverter with jumper cables and it worked fine until I tried adjusting the low cut-off and restart voltages. After selecting their Victron AGM battery profile (funny all of these special profiles are exclusively for Victron batteries) I tried setting at 20.4V and it kicked up the restart to 24.5 minimum. That shut it down as I was just over 24V and I didn’t want to hook up a charger to it in that configuration. I was able to reset it to the 18.6/19.8 level (which seems awfully low for AGM’s) and I turned on again. With that successful test, tomorrow I will start mothballing the Tesla battery and the battery monitoring system, and replace with 4 cheap SLA’s (That’s still $400+ ..grrrrr…) to get us out the door until I figure out something better. Does anyone have a better idea?
Meanwhile I still have an open question about the low voltage cutoff setting on the Victron Community site. One of the techs posted the answer about the inverter not doing less than 7s and the matter is closed. I think the Victron folks are impossible; IMHO, they have not only completely misrepresented their product, they have reduced the capabilities of it after I bought it. Not to mention the time and money invested in the rest of the system. What the heck is the CEO doing in these emails? If he was doing his job of CEO maybe he would be able to see the big picture better? I believe that eventually the market will straighten them out and I can bring my Tesla system out of mothballs.
Can you now use your Tesla Batteries?
Victron Announcement
==================
Reduced minimum DC Input low restart voltage
The minimum DC Low Restart has been lowered for 24V models from 21.8 to 20.6, and from 43.6 to 41.2 for 48V models. Unfortunately, we have not been able to reduce this minimum for 12V units, due to hardware limitations.
This change caters for lithium batteries, and especially second-life batteries such as re-used Tesla power packs. It’s not necessary to update the firmware of the inverter/charger to use this change.
https://www.victronenergy.com/blog/2019/07/17/ve-bus-firmware-460-veconfigure-and-venus-os-v2-33/
Hey David, what do you mean by your BP220 ‘placed in reverse orientation’? Do you have the charge leg from you solar charge controller going in the output side of the BP?
Jay, By reversing my BP220 I mean that I install the second BP220 to stop my solar from charging the Tesla Battery. Here is how: First, I am going to call the two posts on the BP220 Line and Load ( I forget what Victron calls them, but, Line and Load will make it easier to understand).
The first BP220 in my configuration comes off the 24v Buss bar (Line) and powers my 24v DC / 12v DC Converter (Load), it is set to automatically stop energy flow from the battery at 19 volts (this protects my Tesla Battery from Over Discharge). The second BP220 comes from my Victron Solar Charge Controller (batt) and goes to the 24v Bus Bar. This BP220 is reversed by connecting the Batt terminal from the Controller to the Line side of the BP220, the Load side connects to the 24v Bus Bar and charges the Tesla Battery. I have created a “Loop”, using thermal relays, which monitors high temperature and low temperature inside the Tesla battery case. I am also using the relay in the Victron Battery Monitor (BMV712) to monitor for an “Over Voltage” condition in the same loop. All relays are NC unless one of those three conditions exist. The loop is then connected to the front of the BP220 and will stop power from the Solar Charge Controller from flowing into the 24v Bus Bar (Tesla Battery).
I don’t have to worry about my Inverter drawing power below 19 volts because it will automatically shut down before it reaches 19v. I do have to worry about the Inverter Charging the battery if the temp is below 32, but, since I will be in the coach and I don’t like to be cold, and the battery is inside the thermal envelope of the RV I don’t anticipate any issues there, however, if it should ever get that cold, I will probably not be on shore power anyway so I will just Manually Control that issue by shutting down the Inverter Charger until I verify the battery Temp.
By connecting the two BP220s to the 24v Bus Bar and directly connecting the Inverter/Charger to the Bus Bar I have avoided the issue of running charge voltages backwards through the BP220 modules into the Tesla Battery.
Thanks for the clarification. Load and line are just fine, Victron uses Out and In for those. When you said you reversed it, I was thinking you meant you connected your solar charger to the Load side which is why I was confused given the ongoing conversation about them not being bi-directional. And also to clarify, when you say you connected your loop to the ‘frontside’ you mean the remote terminals I suspect.
I too am going to move my initial BP220 to be between the positive bus bar and the DC converter. Because just as you have said, my battery is inside the rig that I live full time in. So the chances that it ever reaches an unsafe charging temp with my wife’s ability to constantly tell me when she’s cold, which is anything below 60 degrees in the coach, means that more than likely will never happen.
This might be of import regarding this issue:
https://community.victronenergy.com/questions/5217/tesla-model-s-battery-multiplus-can-not-turn-on-in.html
Will 20.6 get us there?
After I moved to this thread after posing in the PHASE2 thread, I was getting teary eyed.
I was thinking my husband was going to kill me for spending all this money on a Tesla battery and BP220, and the Victron 24/3000 for *nothing*.
Tom, as always, great presentation. One question.
I don’t require the Multiplex inverter in my application, so a dpst relay won’t be required, Do you know if a BP220 can be operated directly from the BMV712? I couldn’t find that information during a quick check of the Victron website.
Thanks!
I’d like to know this as well as I do not use the multiplex inverter. Can one of the bp220 be controlled directly by the bmv-712? Thanks
I am looking at 6 Tesla Packs, you think it would be better paralleling 2s3p with those packs in a 48V system?
As with many things in life, there are trade offs. 48 volts is more efficient in wiring, chargers and inverters are more efficient. However, there are fewer things that run on 48 volt than 24 volt. And things like inverters tend to be more expensive. So see if what you want is available in 48 volt. If it is, I would definitely go with 48 volt. Your going to have about 26 KWh of usable power, so might as well be efficient.
An additional consideration for your Six Module System… configure your system with three modules in Series. this gives you a max voltage of 72 volts. The 48 volt Victron Inverter can operate up to 68 volts, this allows you to access 95% of the Tesla Battery Module and eliminates the issue of the Inverters not being able to access the lower voltages of the Tesla Battery because the Inverters are designed for a Lead Acid World.
The 3 in Series configuration will allow you to access 95% of your Tesla battery bank, whereas, a 2 in Series will not allow you to access the energy below 37.2 volts (Tesla Modules operate as low as 36v) which equates to being able to access only 74% of your battery capacity. The 74% figure assumes that the Inverters will actually operate at their lowest voltage rating, something those of us with 24 volt systems are finding out that Victron Inverters do not do.
The more I think about this, the more I would configure a system with 3 Modules in Series for sure, it eliminates all the issues associated with the High Efficiency, Low Voltage, world of Lithium-Ion versus the Low Efficiency Lead Acid world that all the electronics are designed for.
In the above comment I noted that the max voltage of a 3 series Tesla battery would be 72 volts and that you could access 95% of the battery in this configuration. Well, I need to make a correction to my above statement, the max voltage of a three series Tesla Battery is actually 75.6 volts and 90% of that figure is accessible by the Victron Phoenix Inverter. I erroneously used 24 volts, nominal voltage, in my original calculations.
Even with this corrected math, you would still have access to a higher percentage of your Tesla Battery Module than you would if you configured the system with two in series at a nominal 48 volts. You also eliminate many of the issues that may be found because the Tesla batteries operate at lower actual voltages than Lead Acid Batteries do.
Man, I wish you could edit comments on this website.
Newbie question, looking at the detailed schematic, are you not grounding the system to the rv chassis?
ty
Krystof, If you look closely at Tom’s original Schematic, you will see that the 12v system is grounded to the RV Chassis and that the 24v system is grounded to the Chassis via the 12v Ground wire.
got it, thank you!
With regards to the 24 volt Victron Multiplus Inverters not operating at their lowest stated voltages, those of you who have not purchased your Inverters yet, might want to consider purchasing the Victron Phoenix Smart Inverter instead of the Multiplus Inverter. I say this because the Phoenix Inverters have a lower stated operating voltage than the Multiplus, 18.6 volts vs 19 volts. Additionally, if you are installing your system in a 50 amp RV you also get the advantage of being able to power your entire coach instead of only one half of the coach, or buying two Inverters.
If anyone chooses to do this please report back to us if you have any success at the lower voltages.
New Tesla Schematic BP Question…
I’m confused about the multiple BP’s; your power starts at your PV (not including your offshore power in) then through the PV Controller through the first ONE way BP, to a Positive Busbar to another ONE way BP but I believe the second BP the poser is trying to go into “out” instead of the “in”? to charge the battery… What am I missing?
Thank you very much!!
Krystof… There are two BP220’s in my system because they perform different functions. If you look at Tom’s schematic, you will see that his BP220 comes directly off the positive terminal of his Tesla Battery. You will also note that he has a BP65 that comes off of his Solar Charge Controller. Tom’s BP220 is configured to stop energy from flowing out of the battery if the voltage drops to 19 volts, this protects the battery from over discharging and killing the Tesla Battery Module. The second BP (BP65) module is wired up with a “Control Loop” that will stop power from flowing into the battery from the Solar Panels if the battery temperature is at (or below) 32 degrees F (0 C), this will protect the battery from being charged when the battery is too cold to accept a charge, which would also destroy the battery. This “Control Loop” also prevents charging if the battery voltage is too high, which is another way you can destroy the Tesla Battery (as well as cause a fire).
Since you are asking about the two BP220s and the “reversal” of the posts I assume you are talking about the system I have described in posts above…
First, let me say that my two BP220s are designed to protect the Tesla Battery in the same way as Tom’s two BP modules are, however, I have positioned my BP modules in electrically different locations based on posts in which Victron states that the BP modules are not designed to handle bi-directional charging.
Second, the BP modules have posts which are marked “In” and “Out”, this indicates the directional flow of electrons and also marks the direction in which the BP module will stop electron flow (from In to Out). This is where I indicate that I “Reversed” the BP220 connections.
Let me explain further, In order to avoid bi-directional charging through the first BP220 (the one closest to the Tesla Battery) I moved the 24 volt bus-bar to right after the 150 amp fuse, I then connected my first BP220 to the 24v bus-bar and then connected my DC/DC converter which provides 12 volt power for my RV. This first BP220 is connected as; 24v bus-bar to the “in” post on the Bp220 with the “Out” post supplying power to the DC/DC converter. This BP220 Module is configured to stop electrons from flowing out of the battery if the voltage drops to 19 volts (dead battery condition), this is all this BP Module will do in this position, keep me from draining the battery to the point of harming the battery. By-the-way, 19 volts is as low as the BP modules can be set, so, that is the cut-off point.
The second BP220 is set to protect the Tesla Battery in three ways, 1) Prevent Solar Charging when the temperature is at, or below, 32 degrees F (I will set this temp to 35 F), 2) Prevent Solar Charging if an Over-Voltage condition exists, I will set this 0.2 volts higher than my actual desired battery voltage, 3) Prevent Solar Charging if the Battery Temperature is too high, I will probably set this temperature somewhere around 100 degrees F (note: I also have a separate cooling fan [and 24v circuit] that will be set to come on if the battery temperature is above 95 degrees F). All of this “control will be accomplished through a “Control Loop” that will be attached to the “remote Contact” connection on the BP220. The “Control Loop” consists of three “Normally Closed” relays that create a “Closed Loop” to keep the BP220 “turned on”, if any one of these relays open up because their condition is present, then the loop opens up and the BP220 stops electron flow from the Solar Charge Controller to the 24 volt bus-bar. The “reverse” installation I mentioned in previous posts refers to the fact that the output terminal of my Solar Charge Controller is connected to the “In” post on the BP220 and the “Out” post is connected to the 24 volt bus-bar, which is directly connected to the Tesla Battery Module. This second BP220 is simply in place to protect the Tesla Battery from being Solar Charged if any of the three conditions, listed above, are present.
PS: I added a Blue-Sea Battery switch just after the150 amp fuse on my system, I eliminated that detail from the above description for clarity and to allow the reader to follow Tom’s posted schematic of his Tesla Battery System.
Great explanation. This is the way the BP should be handled based on all the investigation I have done.
Thank you for the detailed description of the schematic but as I understand it the BP 220s flow one way only am I right? so if the power is coming from the first BP 220 from your PV to the positive busbar how does it get to the battery if it hass to go through a second BP 220 that is flowing from battery to the bus bar? Wouldn’t the flow originating from the PV’s be Stopped at the second BP next to the battery?
Ty!!!
Shouldn’t the electricity flow from the first BP from the PV directly to the battery itself instead of a positive bus bar in front of another BP?
Krystof Andres… Let me try to eliminate any confusion you may still have…
In my description above the energy flow for the first BP220 is this: Tesla battery – 150 amp fuse – 24v bus bar – BP220 (in post) – DC to DC Converter – 12 volt RV systems. This BP220 stops energy flowing from the battery to the DC/DC converter if the battery voltage drops to 19 volts. There is no reverse energy flow from the DC/DC converter to the Tesla Battery because the DC/DC Converter has no charging capability.
Now the energy flow for the second BP220 is this: Solar Charge Controller – 60 amp fuse – BP220 (in post) – 24v bus bar – 150 amp fuse – Tesla Battery. This is the Solar Charging circuit and this is the PV to Tesla battery charging circuit. Energy flows from the PV to the Tesla battery unless the “Closed Loop” is opened because one of three battery conditions are present; over heated, over charged, or too cold, if any of these conditions exist then the BP220 stops the energy flow from the Solar Charge Controller to the Tesla Battery. There is no (high) energy from the Tesla Battery to the Solar Charge Controller flowing through the BP220 so there is no risk of fire from the BP220 as noted in above posts by Don Cobb (note: there is some [low] energy flowing from the Tesla Battery into the Solar Charge Controller that is being used by the Controller to power itself but the BP220 only stops energy flow in one direction [from in post to out post]).
Another way to look at it is:
If you reference Tom’s schematic I have moved my first BP220 to the other side of the 24v bus-bar so the PV energy does not have to flow through it to get to the Tesla Battery, my circuit is: PV – 24v bus bar – Tesla Battery.
Just curious, why did you use a bp220 to protect the dc-dc converter?
why not a smaller version? Does it matter if its “oversized”
thanks
Ty David.
At the bottom where you say: “If you reference Tom’s schematic I have moved my first BP220 to the other side of the 24v bus-bar so the PV energy does not have to flow through it to get to the Tesla Battery, my circuit is: PV – 24v bus bar – Tesla Battery.“
That is the route that makes sense to me but I’ve responding from looking at the schematic at the top of this site which has the pv juice going through two BP’s and that’s what has had me scratching my head…
Ty for all the info, once again.
I will follow your instruction on the adjusted flow from pv to bp to battery..
k
Finally got my system connected but I must be missing something… Going into this my understanding was the BP’s are being used to set under and over voltage cutoffs, so far via the bluetooth option settings I can only set these BP’s for low V cutoff points…. what am i doing wrong? TY
Kristof… The BP220s are designed to protect your batteries from an under voltage condition, normally, the Lead Acid Battery Chargers handle the job of protecting your battery from over voltage. In our Tesla Battery install, it is possible that an over voltage situation could occur if our Solar Charge Controller (or Inverter/Charger) failed to shut themselves off at the correct voltage. The consequences of over charging the Tesla Battery are too great to ignore, consequently, we have built-in a “Failsafe” mechanism to protect the Tesla Battery from being over charged. This mechanism is a “Closed Loop” that is attached to the “Remote” connection on the front of the BP220, if this Closed Loop is broken, then the BP220 will stop the flow of energy from the Solar Charge Controller to the Tesla Battery. In my posting of May 16, 2019, I explain my “Closed Loop” system and how I use this loop to control, Under Temp, Over Temp, and Over Voltage, three conditions where you do not want to be charging your Tesla Battery.
I think you are overlooking the Remote terminals on your BP220 and thinking the BP220 is designed to control over voltage as well as under voltage. The “Closed Loop” uses the remote terminals as an “On/Off” switch to stop Charging of the Tesla Battery. This “Loop” is outside of the BP220 and was created to act as a replacement “Battery Management System” to protect the Tesla Battery from damage in the case of freezing, overheating, or dangerous over voltage.
Re-read my posting of May 16, for a complete description of how this “Closed Loop” is designed and how it is connected.
If it helps, start the design of your closed loop as a simple on/off switch, then add one component at a time until you have your own “Closed Loop” system.
Thanks for that. I came up with that question because most reads/forums, before I installed the bp, would just loosely say/describe the bp to protect both ways, under and over…
One more question, hopefully..
As far as utilizing the relay on the BMV712 to control one or more of the BP’s, on the schematic it seems to show that power is being sent to the 712 and powering the splitter, so you are powering the 712 and its sending cut off info with that same wire? Isn’t power already being sent to the 712 via the control cable it came with?
TYYYYYYY!!!
Kristof… The control does not come from the existing wires going into the Battery Monitor. Your “Control Loop” is a separate pair of wires that goes into the back of the battery monitor using the NC “Relay” terminals and then programming the Battery Monitor to open the relay if an Over Voltage condition exists.
I get that, I was confused bcs the color of wire (red) shows it coming from 712 to splitter then to a power source but I think what you r trying to show is control loop coming out of 712 to board and a separate power cable to power the board coming from your battery?
Anyway, I believe I understand, ty for your time and explanations, much appreciated.
I lied, last question 😅
So I can’t find any info on what the three different connections on the back of the 712 mean. You mentioned to use NC but what’s the second connector that I should use and which ones which? Lol
Ty!!!!
Kristof… No Problem, happy to answer.
The three connections on the back of the Victron Battery Monitor are for the internal relay:
NC = Normally Closed
COM = Common wire (to both other wires)
NO = Normally Open
NC means that the relay is normally closed (i.e.: completing the Closed Loop) unless the relay condition exists — in our case “over voltage”.
So, if you think of the closed loop as a simple on/off switch (connected to the remote connection on the BP220) the two wires coming out of the BP220 go into the back of the Battery Monitor (NC + COM) and the relay completes the loop by internally connecting the two wires together. If an Over Voltage situation exists the relay will open and break the loop thereby turning off the BP220 and stopping electrons from flowing into the Tesla Battery from the Solar Charge Controller.
Be aware that you have to set the parameters on the Battery Monitor to properly open the relay (be sure to perform a test to ensure proper protection of the Tesla Battery).
Now, you can simply add your other two thermal relays onto that same closed loop and protect for over temperature and under temperature.
Awesome, ty.
I’m definitely using the relay for over voltage. Again, I’m sorry but not clear on which wire goes where from the BP to the back of 712, BP has a L and h output, how should they correspond? Ty ty ty 🙏🏼
Kristof… You are using the “Smart” Battery Protect versus my “Dumb” BP220. If you look at the remote pins (L & H) there is a loop of wire that connects them, this loop must be closed in order for the electrons to flow through the BP module (from in to out) to the Tesla Battery. This loop is the same “remote” loop on both the Smart and Dumb versions of the BP module and will work identically. Which wire goes to which post does not matter as you are only making a “Closed Loop” which acts as a “remote” on/off switch for the BP Module.
Think of the loop this way; currently, there is a simple loop of wire connecting the two pins which represents the “On” position of a switch. You are going to lengthen that loop of wire by taking two wires and inserting them into the back of the battery monitor (in the Normally Closed and Com holes) the internal relay completes the loop thereby allowing electrons to flow from the Solar Charge Controller to the Tesla Battery.
The relay inside the Battery Monitor simply acts as a “Remote” switch which is normally in the “on” position (NC) unless an Over Voltage condition exists, then the switch turns itself off by opening the relay and breaking the Closed Loop.
David, ty very much for that explanation.. It all makes sense now 🙂
The ‘last’ question is how do you assign the NC port of the 712 to be the high voltage cutoff?? TY much Sir
Kristof… That answer is in the documentation for the Battery Monitor. The section takes careful reading and thought. The reason I can not answer (yet) is that I have not yet set my own Battery Monitor ( I have a couple of solder connections to make before my “Closed Loop” is complete). I will have to sit down with the manual and be at the Monitor when I figure it out. I will then test it by setting the Over Voltage slightly lower than my charge voltage and charge the Tesla Battery to that point to see if the Battery Monitor performs the Over Voltage protection. PS: I will probably need to drain my Tesla a little bit before I perform this test.
David, copy that, apologies, I didn’t know you haven’t completed this detail yet. I will dive into the manual and do a test as you described..
thanks again for your time and information! Best of luck on your adventures!
Greetings
Spent over an hour going through the 712 manual, no details really describing the use of the outputs. Ran the battery down and did a brief test of increasing the voltage in my charge controller to put out a higher voltage, changed the high voltage parameters in the 712 to like 22v and the bp never cutoff… probably not the best test but currently couldn’t think of a batter way to do it…
Kristof,
Are you using the Victron Connect on a smart phone to program the 712? That is really the best way to do the programming.There is a manual from Victron for the settings for the battery, etc called VictronConnect – MPPT Solar Charge Controllers that gives you all the settings.
And make sure that you have the remote switch wires installed from the 712 (common and NO on mine.) to the remote switch on the MPPT.
Hope that helps.
Don,
Yes, using my phone to program.
Im using the smart mppt 100/30 controller, it only has a VE. direct plug, no way to plug in a controller cable..
Krystof,
Sorry, got my questions mixed up. Just so I’m clear, you are trying to use the 712 to shut down a BP when the solar charger gets the battery voltage too high. Is that correct?
Since it is working at all, you have the remote switch on the BP closed, so that is good. So you should look at the wires that go from the 712 to the BP. On the back of the 712, the wires are plugged into the Com and NC. On the BP, the wires are plugged into the 2 pin block that is the remote switch. Is that your setup?
As far as the connection to the battery from the MPPT. The cable from the MPPT goes the the terminal in the middle of the BP and the cable to the battery goes to the terminal on the outside of the BP (mine is labeled IN for the middle terminal and OUT for the outside terminal but this labeling is not standard.)
Your test sounded reasonable, when the battery voltage got above 22 volts the BP as controlled by the 712 should stop the MPPT from any further charging.
Don
You are correct, trying to get the 712 to communicate with my 65a SBP that is wired right after my MPPT.
PV-> 30a Breaker -> MPPT -> SBP -> TESLA Batt. Is the order of components.
Correct, the wires are connected with the same orientation you described from the 712 to the BP. (Com and NC, remote switch on BP).
I just don’t see anything in the documentation or the Victron app that talks about or has anything about setting parameters to control the outputs of the NC port but maybe that signal automatically gets transmitted when you set your maximum voltage?
So far no luck with this setup. Thank you Don
It has to be something in the 712 settings. So go to the Relay section. Under Relay Mode -is it set to Remote? Is the High Voltage Relay enabled and set to your test values (cutoff at 22 volts and clear an 21.9 for example)?
FYI, you set parameters in the 712 relay section which controls the remote switch on the BP.
Another great addition is to by the temperature sensor for the 712 and then you can also program the 712 to stop charging below freezing (a big no-no).
If none of these suggestions work, you may have a defective unit. I can’t think of anything else that might be wrong.
Ty Don, I’ll double check that it’s set to ‘remote’ but def. have the high voltage relay turned on.
I did make sure to get the temp. Probe 👍🏼
Gentleman, still no luck.
Don, are you using this configuration (high voltage cutoff via 712) successfully?
I’m going to try this board connected directly to 65 SBP, hopefully that doesn’t the trick…
Battery Charge Controller Protection Switch Digital Display On Off Relay Charge Controller for 48V 36V 24V 12V Battery https://www.amazon.com/dp/B07QX5KDK8/ref=cm_sw_r_cp_api_i_UlckDb8CBH74V
Kristof… Sorry this has been such a challenge for you. I looked at the Battery “Charge” relay you noted in your last posting. I am assuming that you plan to wire the Tesla Battery output to the “In” side of the terminals and the “Control Loop” to the “Batt” side of the terminals. My concern with this solution is that the “Batt” terminals will be energized and the Victron BP will get damaged.
If you test your new Circuit Board and you do find that the “Batt” terminals do, in fact, get energized, then you can simply connect a 24 volt, automotive relay to the “Batt” terminals and connect your control loop to the NC (Normally Closed) terminals on the relay and power the relay with the output from the “Batt” terminals. You can then program your new circuit board to “shut off” once you have reached the “Over Voltage” number that you have programmed into the new circuit board. This additional relay will perform the same function as the BMV 712 relay would have ( basically, keeping your control loop closed until an over voltage situation occurs).
Yeah it’s been a bit frustrating.. thanks for the tips, definitely noted on the voltage reaching the BP.. I haven’t tried the board yet, haven’t had the time and a bit apprehensive installing a $15 board to take on such a important task..
ty
K
Kristof… Just wanted to let you know how my programming of the Victron Battery Monitor has progressed…
I completed the final connections for my “Control Loop” and the “NC” connection on the back of the BMV 712 did, in fact, operate as expected, in-as-much-as, the NC terminals were closed and they completed my control loop. I was also able to verify operation of my control loop by manually opening the loop and verify that the BP220 does, in fact, stop the flow of energy from my Solar Charge Controller into the Tesla Battery. Additionally, I was able to set the parameters on the Battery Monitor, through the Bluetooth connection, to trigger an alarm on the battery monitor and send an alarm message to my Smartphone via the Victron Connect App.
I have determined that the BMV 712 relay settings have to be done manually through the BMV 712 and not through the Bluetooth interface. My next step is to program the relay settings into the Battery Monitor and test out the operation of the relay.
I will let you know when I have done this and my results.
I think the key to solving this is manually entering the Relay Parameters into the BMV 712 (parameters 11 through 21).
Hey David, thank you for the update! Good to know about the necessary manual programming needed to make it work properly…
cheers!
K
Kristof,
I just checked my system and found that my cutoff relay was not working. The problem was in the BMV712 settings. Under Relay, use the default setting. If you read the manual carefully, only then will the settings for the relay be utilized. My system is now working.
David,
I used the Connect app and compared changing the settings with the meter and with the app and it appears that they both change the settings, so I’m not sure the manual changing is the issue.
Don!
I’ll give that a try but pretty sure I had no luck whether I was in ‘default’ or ‘remote’ modes in the 712 🙁
Thanks for the updates!
K
I’m confused about running the tesla modules in parallel.
When I looked options for using the original tesla BMS at http://www.orionbms.com the manual states this:
“Paralleling Multiple Tesla Modules
CRITICAL NOTE: Because Tesla modules contain multiple cells in series, they CANNOT be
directly connected together in parallel without taking sufficient precautions and design strategies.
Even though Tesla modules have a fairly large capacity, often times an application will demand
an even larger capacity than a single module itself can provide. The only way to achieve this
with Tesla modules without increasing the pack voltage (by placing modules in series instead of
parallel) is to introduce parallel strings (that is, the parallel connection of series strings together
to form multiple discrete high voltage battery packs).
This is not a trivial task and requires the use of a separate (discrete) BMS per string being
used, along with other support equipment and supplemental engineering work.”
Also here: https://secondlifestorage.com/t-DIY-PW-from-2-Tesla-battery-modules?pid=35922
is stated: “3)24V works parallel works, but see 4)
4) you are faced connecting a bms to the Tesla modules that will be able to talk “can-protocol” to the inverter,”
I know that the can-protocol is what the tesla main computer uses to provide instruction to the build in BMS in each module.
My question is this:
Tom, your schematic seems to indicate that you can just parallel them as normal batteries, and I also thought that they would work like this. I’d much rather parallel the two modules I was going to use and keep it at 24v instead of running them in a 48v series. I’m not able to come up with any reasoning why each module would require a separate BMS. Can you think of any?
You can certainly use the batteries in parallel. I am using 4 batteries, 2 in series and 2 of those in parallel (2s2p).I think part of the issue with what you are reading is it is using the Tesla BMS. That is not easy and IMHO not really necessary. What you want to do to protect your batteries is to control over/under charging and over/under temperature. You also want to insure that the cells in a battery are balanced. I’m using the Victron BMV 712 to control the MPPT controller as far as low temperature and over charging. My inverter won’t work at a low voltage so that is taken care of. The over temperature is taken care of with an alarm and a temperature controlled fan. The balancing is done with the Battery Meter / Balancer Tenergy 5-1. If you don’t over charge or discharge the batteries, you should only have to check this monthly and it is usually fine.
You can use a BMS is you want, there are several on the market that will do the balancing and cut off at low or high voltage. The problem is the Tesla is a not standard setup (6 cells in series) instead of the more standard 7 cells in series. So you need to get a BMS that will be adjustable. Not always easy to find and they don’t always adjust the way you want.
My suggestion is to 1) Don’t over charge or discharge your batteries. For a 24 volt system a good range is 20 to 24.3 volts (about 20% to 80% SOC). 2) Control the low temperature and high voltage with the BMV 712 and 3) check the cell balance with the Tenergy 5-1 on occasion Everything should be fine.
I have been running two Tesla modules in Parallel without issue for the light draw it is seeing. The modules have not fallen out of balance at all. I do use a BMS for each module that does auto balance and has alarms that can shut down or turn on all the Victron Equipment. It is the Electrodacus SBMS0 and is fully programable.
hi, do you have any more info on how you hooked up the SBMS0 with your 2 modules?? (parts used)
thanks
Can anyone answer this? I do not use a multiplus inverter. Can one of the bp220 be controlled directly by the bmv-712 without the use of a dpst relay to shut the system down do to temps? Thanks
What is everyone’s opinion about this video which recommends against using Tesla batteries based on his test results?
https://www.youtube.com/user/errolprowse/videos
I first saw this video just after I had purchased 2 Tesla batteries. So I had to watch it several times to get it straight. I like Will, I have learned a lot from him. And he makes some valid points. For example,
1. These batteries can be very dangerous. Not very likely in my opinion if you are careful.
2. Because of their Odd Ball structure, you will have issues with most standard equipment designed for lead acid.
3. You will need to install your own control systems to protect the battery (BMS, high/low voltage and temperature cutoff, etc.
4. If you don’t know what you’re doing and don’t want to put in the hours to learn, stay away. This is not an easy solution.
That being said, I don’t agree with his financial model. Battleborn is not a little more expensive, it is a lot more expensive. Like 250% more expensive. If you are talking about an RV and one battery, the cost difference is not a big factor. But if you are setting up a system for a house it would be substantial ( like $10,000 more to go with Battleborn to get 20 Kw). Offsetting that cost would be the $500 or so to build your own control system.
I also disagree with his problem with using the battery between 20% and 85% SOC. That range gives you a very long life span on your batteries, so I don’t see that as a problem.
So did I make the right decision sticking with my Telsa batteries? So far yes. I got more storage capacity and do not use the grid much at all. I have saved money. It was more work and I watch it very closely. However, check back with me in 12 years when the system has paid for itself and see how the batteries have held up.
Don, I agree with you on the advantages of cost per Kwatt with Tesla over Battle Born. I have employed the Electrodacus SBMS0 per module and have a complete safe system.
On thing about the BB that is not talked much about is the BB BMS documented failures when BB are placed in parallel. Use of multiple Batteries at same voltage. This failure is caused because the internal BB BMSs do not talk to each other. BB may be assembled in the USA, but the Life cells and BMS are made in China.
SIMPLE RELAY SOLUTION – REPLACEMENT FOR BP220/65
I’m using nearly all of Tom’s design for an install on my sailboat – THANKS TOM! The one major change is that I’m replacing BOTH BP220’s with a single perfectswitch from http://www.perfectswitch.com They offer a series of awesome, bi-directional, voltage protection relays that are fully programmable and accept external inputs. I’ll replace the BP220 (between the battery and bus bar) with this unit, set minimum and maximum disconnect and reconnect voltages, then feed the BMV712 relay output to the PerfectSwitch’s trigger input, which creates a backup voltage disconnect in addition to the temperature disconnect. I’ve spoken to Scott at perfectswitch several times. He’s been super helpful and patient! These switches aren’t cheap – $650-ish. but you get rid of 2, BP220’s and add another, Victron and Bluetooth-independent safety without a Rube Goldberg solution that adds complexity and several unnecessary failure points.
James,
Yes a good solution but expensive.
I went with a high quality $160cad BMS Electrodacus SBMS0 and a $40 500amp 24 volt Kilavac Contactor.
Do you place a pre charge resistor on the perfect switch to account for the compasitive load? Or does the perfect switch account and control the inrush because of the use of electronic switching?
Tom
Tom,
I have based my Tesla install in my Winnibago View 24j much like yours with minor updates. Stem 1, I removed the Victron BP220 from between the battery and Multiplus and replaced it with a simple Kilavac 500amp 24 volt contactor, pre charge resistor, and simple low voltage shut down Chinese PCB relay.
Step 2 I installed a high quality minimum cost BMS. The Electrodacus SBMS0 ($160cad). The SBMS0 alarms talk well to all the Victron equipment to shut down over charge and low temp charge with the Multiplus, Smart MPPT, and if you use Smart Orion TR. The low voltage shut down will turn off the BP65,100,220 on the 24volt bus and shut off the Multiplus inverter.
I hope you consider updating your Tesla system after you return from Alaska.
Tom
Hi Thomas –
Your question is way above my knowledge level so I pushed it back to the PerfectSwitch team. I pasted their response below, but also want to note that I required an overcharge failsafe that is completely independent of the Victron system. Their switch also includes a highly programmable smart fuse, which eliminates the need for the 200A fuse by the Main Disconnect in Tom M’s diagram. I’m leaving it in (since I bought it already) and had the PerfectSwitch programmed for disconnect at 3 different amp draws and draw durations that should make it redundant, but I like redundancy on a boat, especially with a family aboard.
No pre-charge resistor is required. Generally, a pre-charge resistor is used in parallel with a primary mechanical relay to limit the in-rush current to the inverter input capacitors so that the current does not flow entirely through the relay, which can cause welding of the contacts in extreme cases. Since the POWER-GATE relay is entirely solid-state, contact welding is a non-issue.
The POWER-GATE relay is designed to handle large in-rush currents; in fact we have had multiple customers, both recreational and military, that have used the relays between a DC source and inverter input without issue.
I assumed since the power switch is solid state there would be no requirement for a pre-charge resistor. Thank you for confirming this.
I really appreciate both of you for the tremendous work you put into these videos. My question, have you looked into micro wind turbines?
Maybe I’m missing something, but isn’t the schematic in Toms post on this page show the wrong use of the BP220? He’s much smarter than I, but after reading all the comments and doing research it would appear that the BP220 should be downstream of the 24V busbar on the leg supplying the 12V system. This would only help with one low voltage scenario, the Multiplus should accommodate the other lower voltage scenario by not inverting below a certain voltage. This doesn’t help address over voltage or temperature conditions though, so assume another device is needed as a fail safe to the Multiplus charging the battery?
I have no issue with the BP220 coming from the Solar Charge Controller.
Tom,
I am wondering if you will have an updated schematic and parts list indicating the relay you are using now as a safeguard against reverse charging. I have been debating adding solar and lithium batteries as my coach batteries on my Class C and lean towards the tesla 24v system you have done. My challenge is finding appropriate space to do it in my RV
thanks
Bob
Bob
I replaced the BP220 between Tesla and Multiplus 24/3000 with a Tyco Kilavac 24 volt 500 amp contactor IHV200HAANA i paid $40 on ebay. I used a 7 watt 120 ohm resistor between the main contactor lugs as a precharge. The contactor is controled as a low voltage disconnect by using a Bosch 40 amp 24 volt 5 pin auto relay, a 3 pin togle switch and a Chinese Low voltage relay shut off HX-M609 $10 and a red led alarm $2. The Bosch relay can be omitted and just control the contactor with the HXM609 or other relays available.
This is used as a last chance under voltage shut off switch since i have upgraded my system with two Electrodacus SBMS0 BMS that can shut down the Multiplus, Mppt, and BP220 on my 24 volt bus for under voltage, over charge and low/over temp battery.
With the BMS the use of the contactor has now become redundant and just a manual master battery switch is all that is needed to place the rv in storage.
Tom
Hi Tom, how did you add the SMBS to your batteries? One SBMS per battery?
How did it work with the 057Tech “board”??
thanks
Since the SBMS0 is only a 8s bms, yes you need to use one SBMS0 for each Tesla Module you have. The BMS balance leads are connected to the Tesla bms leads in a 6s configuration and the SBMS0 is programmed for low voltage and upper voltsge per cell. The automation leads are connected to shunts and to my multiplus and BP65 and BP220 so it can shut down charging during over voltage and below temp as well for under voltage.
The instructions are online and you can read over the manual.
I dont use the 057 tap board, but it will work directly. I just soldered a JSTXH7 header wired directly to the Tesla balancing wires and the balancing cable to the SBMS0. You can also use Molex or any connectors you like.
I need some help with my install. I have 4 tesla batteries 2 in series, 2 in parallel. I have currently 6-300w panels that in the winter in colorado peak at about 1000 watts. My issue is the chargers not switching into float mode. I set these at 48.8V and the bmv712 smart is showing 49.3V.
I have the victron 10kva quattro, 150-45 smart charger, Bmv712 smart all running through the color control GX. In standby mode the inverter draws about 75w constantly. There is no A/C input currently. Also there really is no large draw during the days because we are finishing our 0Bus-to-RV conversion and not traveling yet.
I have also noticed that when the BMV712 Relay is closed, it is still allowing charge into the batteries. When the BMV712 is triggered is it supposed to allow charging and not discharging, or separate the batteries completely from the system?
Thanks for any help. I am just trying to figure out the relationship of the victron products to my battery setup, so I don’t incinerate the entire bus before we use it, :).
I should have included my AH setting is 466ah and my battery voltage capacity is set for 50.4V.
Should I change my battery voltage capacity to 49V so it appears to the charger to be 100% at 49V? Then change my settings from 90% SOC to 100% SOC at the 49V?
Again, thanks for any help.
You need to use the remote switch setting to control the Victron MPPT. And then you need to have the remote switch setup between the 712 and the MPPT.
I have my setup to cutoff at 48.75 volts as the absorption voltage and the float voltage at 48. You have a different configuration than I do, so I’m not sure about how to control the Quattro or GX.
Hope this helps.
Tom – I recently implemented your Tesla 24 Vdc Solar system design. I adapted the design to fit a 48 V dc I3 BMW battery. It worked fine but I BP48 (your equivalent BP 220 Battery protect) would not start up connected to my inverter (Schneider Conext SW 4048) It displayed the error code E1 (short circuit). So I connected my inverter directly to the load side of the fuse before the BP48, This resolved the problem but also configured the circuit so only current flowed in the forward direction during charge through BP48s. Which seems to be a hot topic on your site since some people think it is a no no, I don’t have that issue at 48Vdc because the the solar current is so low (20Amps) but the inverter has more charging current and is directly connected. I will rely on the 712 disabling the inverter when the 712 see a over voltage condition. Not sure what you think about reverse current? It seems fine to me to source the reverse current as long as the current is controlled (fuse) and the BP device can handle the power. What do you think? Your design slightly modified for 48 Vdc has been working well for several days. Thanks for all the help!!!
Catching Air
Jeff
Use the BP only in the correct direction. Use a second BP. A Victronn moderator stated they could catch fire. It was stated in here somewhere with the link. Even with a low current you should not take chances. It is disappointing that victron does not provide this information in the documentation.
I have exactly the setup you described. You should not have current flowing in both directions. It worked for me for awhile and then it burned out the BP220. Since you are using the Schneider as a charger and inverter, the BP should not be connected to the Schneider leg at all. The 712 will not stop bad things from happening. In my case it just burned out the BP, but there are pictures of it actually catching fire. Not a good thing.