Gen 1 vs Gen 2 BMS help

Discussion about components from Ampera/Bolt and the PSA group which owns Opel these days
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Skudak
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Gen 1 vs Gen 2 BMS help

Post by Skudak »

Can someone point me towards some info on the difference between gen1 and gen2 Volt BMS slave firmware? I have 2 full packs with Gen1 slaves and I can read all the cell voltages fine, but I cannot get them to balance. I have a single gen2 slave that came with a spare battery I bought from a guy that was using volt batteries for solar backup. The gen2 I can get to balance and read cells perfectly fine on any battery. But if I swap a gen1 back in, it doesn't work.
For can messages I'm using:
0x200 for BMS init, then ID 0x300 for balance frame 1 (8 bytes), then ID 0x310 for balance frame 2 (5 bytes)
I send the balance frame every 200ms I think

Edit: I'm actually not sure which gen I have now. The red board (which works fine and I assumed was gen2) is dated 12/23/2009 and the green boards (the ones they don't work) are 04/08/2011. So the 2011 ones could be possibly be post 2012 model year.
KimchiKimKim
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Re: Gen 1 vs Gen 2 BMS help

Post by KimchiKimKim »

Are you sure you are working with gen 2 BMS? I'm pretty sure that BMS isn't distributed. Can you add some pictures of your test setup?
Skudak
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Re: Gen 1 vs Gen 2 BMS help

Post by Skudak »

KimchiKimKim wrote: Wed May 31, 2023 2:09 am Are you sure you are working with gen 2 BMS? I'm pretty sure that BMS isn't distributed. Can you add some pictures of your test setup?
I'm not sure actually. Here's photos of the two boards. My test setup is just my VCU wired directly to 1 slave instead of the whole set of slaves so I can try 1 at a time. I have a can sniffer that says the VCU is sending the right messages. It's also reading the cell values perfectly fine from each board, but only the red board will balance.

Looking at the dates on the pcbs, it's possible that the 2011 dated ones could be post 2012.

I may have my nomenclature messed up, I considered pre-2012 as gen1 and post-2012 as gen2 based on battery size and how salvage yards separate those years.
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tom91
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Re: Gen 1 vs Gen 2 BMS help

Post by tom91 »

Did you check if there are any wiring differences for them?
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Skudak
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Re: Gen 1 vs Gen 2 BMS help

Post by Skudak »

tom91 wrote: Wed May 31, 2023 1:33 pm Did you check if there are any wiring differences for them?
As far as the traces on the pcbs? They appear identical, just different colors. As far as the slave wiring itself I don't really have a way to look. The red slave that came on the spare battery I bought was missing all the wiring so I have nothing to compare to. The connections on the top of the battery look the same.

The part that isn't making any sense to me, is all 6 slaves that came on the batteries communicate cell values fine (Which tells me I have the 5v, Ground, and can-bus wired correctly?), but wont balance. The one red board from an unknown pack I can swap in (like I use the wiring from the green ones and just plug it into the red one) and it will communicate fine AND balance.
Skudak
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Re: Gen 1 vs Gen 2 BMS help

Post by Skudak »

Some extra info I forgot to add: at one point, these slaves were balancing correctly and had all the cells within .01v. One day though I discovered that the slaves appeared to be unbalancing the packs from each other (even though nothing in my code changed). Like the large battery cells read 4.0v, the small battery read 3.9v, and the medium battery reads 3.8v. This is true for both packs (I'm running 2 complete chevy volt packs, each on its own can-bus), like exactly the same. The cells within each battery all are within .02v. I assumed this was something screwy in my code, but I couldn't find anything weird, and ever since I caught that I can't get the slaves to do anything, even running my old code they still don't do anything at all. I'm wondering if they burnt out or something.
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