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Lithium Ion NMC with 48v Sol-Arc - Battery Configuration / BMS / Charge Questions

mjsfbay

New Member
Joined
Sep 8, 2021
Messages
27
I recently received 8 Lithium Ion NMC battery packs. Here are the battery specifications.

Each cell labeled:
- CA1 060G6
- +3.7 V
- 37.0 Wh
- 10000 mAh
- BM1740310368

Some of these tested at 12V and some at 16V.

Each cell is labeled as 3.7 W nominal, however, some of the cells are testing at 3.01V (those are the packs testing at 12V) seen labeled here:

Lithium Ion with Buss Bars.jpg

Lithium Ion_pack.jpg

Questions:
Is the difference in voltage an indicator that some of these cells may be bad?

When individual cells are charged at 4.0V (my preference for > cycles) each pack will be 16V. If I wanted to connect these to a Sol-Ark for storage, would I be able to connect 3 in series for a 48V pack?

I have 8 total packs, so I think the ideal arrangement would be:

2p / 3s(48V)

This would only use 6 of the 8 packs. Is there a way to incorporate the remaining 2 packs?

Another option I see is that it appears each of the packs (currently arranged in 4 rows of 14 cells) can be separated into 4 rows of 7 cells). In this case I would have 16 smaller packs rated at 16V if placed in parallel. If done this way I could have:

5p / 3s(48V)

Would this be correct or am I at risk of burning my house down with this logic?

What would the BMS look like in such a build?

Would you feel safe with a Lithium Ion NMC battery bank inside your home?

I realize I've been asking a lot of questions on this forum... that is because I'm over my head and could use some help that can't be found on youtube or any other media that I'm aware of.

I'm happy to pay a consulting fee to an expert that can help guide me through building this battery bank safely.
 
Last edited:
I recently received 8 Lithium Ion NMC battery packs. Here are the battery specifications.

Each cell labeled:
- CA1 060G6
- +3.7 V
- 37.0 Wh
- 10000 mAh
- BM1740310368

Some of these tested at 12V and some at 16V.

Each cell is labeled as 3.7 W nominal, however, some of the cells are testing at 3.01V (those are the packs testing at 12V) seen labeled here:

View attachment 69094

View attachment 69104

Questions:
Is the difference in voltage an indicator that some of these cells may be bad?

When individual cells are charged at 4.0V (my preference for > cycles) each pack will be 16V. If I wanted to connect these to a Sol-Ark for storage, would I be able to connect 3 in series for a 48V pack?

I have 8 total packs, so I think the ideal arrangement would be:

2p / 3s(48V)

This would only use 6 of the 8 packs. Is there a way to incorporate the remaining 2 packs?

Another option I see is that it appears each of the packs (currently arranged in 4 rows of 14 cells) can be separated into 4 rows of 7 cells). In this case I would have 16 smaller packs rated at 16V if placed in parallel. If done this way I could have:

5p / 3s(48V)

Would this be correct or am I at risk of burning my house down with this logic?

What would the BMS look like in such a build?

Would you feel safe with a Lithium Ion NMC battery bank inside your home
I realize I've been asking a lot of questions on this forum... that is because I'm over my head and could use some help that can't be found on youtube or any other media that I'm aware of.

I'm happy to pay a consulting fee to an expert that can help guide me through building this battery bank safely.
Good morning, I to am building a battery bank using NMC. I have done weeks, probably a month of research on this chemistry. From what I have found it is safe, the takeaways so far are 1) is to make sure that the battery bank is bigger than what you will be needing for power to lessen the amount of "activity" the cells need to discharge/charge, the more you can limit that curve, the less chance of any thermal "runaway". 2) No need for a BMS, I know some will chime in and call me crazy, there is a gentleman on you tube who has a really big battery bank from NMC EV's and he has had his wired up for 5+ years with no BMS and no issues. Basically each Battery pack in parallel MUST have the same length and gauge wire to point of connections! This way they will get equal charge and discharge. 3) A breaker for each battery pack at that point of + connection to avoid a possible Thermal runaway, your batteries may already have a built in fuse for that. 4) Temperature of battery MUST be above freezing during charge mode! (check specs of battery) ie. heated environment. I would feel safer with my batteries in outside heated building/shed or in an enclosed fire box personally, just on the safe side, he has his in his house garage. Not sure on the wiring configuration, I am leaning towards the longer series and fewer parallels, if you find out what configuration is best and what final voltage for the 48 VDC inverter please let me know.
 
Oh, one more thing, I would pre balance each pack prior to tying them together, just on a slow charge to a set level, ie. 3.5-3.7
 
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