[Spaceweasel]

I have three 12s modded Tesla modules (148v total). Any recommendations on a BMS?

 

[4Foxtrot]

Search "simpBMS" it uses tesla PCB's AND loom, .. so will save hours of wiring with Orion's etc

 

[Spaceweasel]

These are modded (6s to 12s, so ½ capacity but 2x volts). 12s Converted Model S Module, 5.4 kWh, 50.4 V max

Would simpBMS still work?

 

[Gigawatts]

I use the Zeva bms on my 12s tesla modules. So its 1 to 1 bms module to tesla module. I have 4 in a Datsun 510 for 48s or 180v nominal.

Zero Emission Vehicles Australia

 

[oudevolvo]

These are modded (6s to 12s, so ½ capacity but 2x volts). 12s Converted Model S Module, 5.4 kWh, 50.4 V max

Would simpBMS still work?

Simp can still work, but then you also need the other eight slave modules from the pack and connect one to string 7 to 12 of each module.
Using Orion, Zeva, Emus etc is more straightforward.

 

[4Foxtrot]

These are modded (6s to 12s, so ½ capacity but 2x volts). 12s Converted Model S Module, 5.4 kWh, 50.4 V max

Would simpBMS still work?

Yes - you specify no of modules and overall Ah
The main advantage over orion etc is you re-use just the tesla loom connectors and its PCB's (I get a good feeling using the tesla PCB, bleed resistors, monitoring etc vs 3rd party). Hence, sorry @oudevolvo I tend to disagree, but always good to hear more experiences for other projects - especially non-tesla batteries <<<here>> is simpBMS setup manual

 

[oudevolvo]

Yes - you specify no of modules and overall Ah
The main advantage over orion etc is you re-use just the tesla loom connectors and its PCB's (I get a good feeling using the tesla PCB, bleed resistors, monitoring etc vs 3rd party). Hence, sorry @oudevolvo I tend to disagree, but always good to hear more experienced for other projects - especially non-tesla batteries <<<here>> is simpBMS setup manual

Well, I do agree with you if the topic was about 6s modules.
However, the question is for 12S modified modules.
What basically happens is that you change from 6s74p to 12s37p
In this proces, some cells are cut off from the 6s string. As I said, these become string 7 to 12.
The original Tesla loom and PCB will still only "see" the first 6s and no longer the strings that have been cut off.
I made this picture to explain:

So if you insist in using Simp and the Tesla slaves you need to come up with a solution linking a Tesla PCB to the other six string.
So that's why I'd say for a 12S module using a third party BMS is more straightforward.

 

[4Foxtrot]

Well, I do agree with you if the topic was about 6s modules.
However, the question is for 12S modified modules.

So if you insist in using Simp and the Tesla slaves you need to come up with a solution linking a Tesla PCB to the other six string.
So that's why I'd say for a 12S module using a third party BMS is more straightforward.

This (as below) still seems simpler to me AND reuses the Tesla PCB's (page 19).
But hey if it works for you go for it - my preference is always simplicity and keeping as standard as possible - there less to go wrong (and yes I know this by experiences .. eg 1st conversion 12 years ago when smart car conversion popped one of its (too many) contactors ... on a train level crossing !!! )

 

[oudevolvo]

Yes, agree again, simplicity is good!
So if you can use 6S modules it is preferred.
However for some reason (eg required voltage) one needs 12S in this case.

As I tried to explain, for 12S modules the manual page you show is incorrect.
Then it should say “Module with slaveS”.

Please do not use just the one single Tesla PCB on the module with Simp with 12S converted modules!! You will miss monitoring 50% of the module.

 

[4Foxtrot]

Yes, agree again, simplicity is good!
So if you can use 6S modules it is preferred.
However for some reason (eg required voltage) one needs 12S in this case.

As I tried to explain, for 12S modules the manual page you show is incorrect.
Then it should say “Module with slaveS”.

Please do not use just the one single Tesla PCB on the module with Simp with 12S converted modules!! You will miss monitoring 50% of the module.

I think we need to ask Tom De Bree aka simpBMS and Zero-EV guru @Tomdb to sort this out. I trust him.

 

[Spaceweasel]

Thanks for the input and discussion, everyone!

I'm using the three modules to get to the desired voltage with a lighter overall weight. I might want to go to four modules later, but right now I just have the three. The modules did not come with any of the Tesla boards.

 

[R4eCV]

Hello @Spaceweasel
Just wondering if you would care to share the outcome of this discussion... which BMS did you use in the end for your 12s modules?
Cheers,
Remi

 

[Spaceweasel]

I purchased the last bits from Zeva as they went out of business. We haven’t hooked them up yet, but will update when we do.

 

[R4eCV]

Thanks a million @Spaceweasel - that was quick!
I might be working on a project with 6 modified modules so really interested to see how things will work out for you. Is there a project thread were you share the details of this build?

 

[munsterwrench]

I purchased the last bits from Zeva as they went out of business. We haven’t hooked them up yet, but will update when we do.

Would you mind uploading pics of the modified packs. I'm curious as to how the mod them.