Will this battery configuration be OK for these BMS?

[flowerspower]

I am retrofitting my RV with a solar power system to be able to run my newly-installed mini-split AC. I ordered and have since received 16X EVE 3.2V 280Ah Lifepo4 batteries. Originally, my original plan was to create 4X 12V batteries by connecting 4 of the EVE cells in series, making 4X 280Ah 12V batteries. The system will provide 1120Ah of power. However, this configuration would require 4X BMS units (DALY Smart BMS 4S 12V 200A), which I think may be overkill with regard to requiring 4 BMS units. I now am thinking of making 2X 12V banks by connecting pairs of EVE cells in parallel then connecting them in series (8 cells per bank) then connecting these 2 units of 8 in parallel. This would lower the requirement of BMS units needed to 2. One question is regarding connection of the BMS balance wires (4 total) for each bank. I would connect each one to a pair of cells connected in parallel. Would this be an ok configuration or should I just spend the extra $$ and use 4 BMS?

 

[MisterSandals]

What you are describing is a 2P4S battery. I have a large battery with this configuration and it works really well. I think its important to capacity match your pairs so that the pairs are as equal as possible within each battery pack.
So in each 2P4S battery, the first pair i had the strongest and weakest cells paired, the second strongest and second weakest paired, ...

Hopefully this makes sense. You have quite a few possibilities with 16 cells so it would be a lot of testing and moving cells around if you detect imbalances.

 

[Bob B]

I have a 2P4S pack as well .... it works fine.

The only downside would be if the cells you receive are poorly matched. Who did you get the cells from? Have you capacity tested them?

 

[flowerspower]

Thank you, Mr Sandals and Bob B. I have taken a while to respond because I have not been able to charge or capacity test the batteries in series untii now. My BMS (DALY Smart BMS 4S 12V 200A) took longer than expected to arrive. The cells were charged to 3.55V and I got 284AH after discharging to about 2.65-2.70V.
I purchased these through Amy Wan, Shenzhen Luyuan Technology Co., Ltd.
The cells cost $123 each. Shipping was $373 to my front door. Total for each cell with shipping: $146.
Time will tell how these work long-term..

 

[Bob B]

Did you order the commodity cells from Amy .... or the matched cells?

 

[flowerspower]

These are the matched cells.

 

[Bob B]

Please keep us informed how they work out for you.

 

[flowerspower]

I will keep you posted. Should have the system installed next week.
To clarify, I’m using 2x of the DALY 200A BMS. Each one will manage 8 cells (2P4S).

 

[Just John]

I will keep you posted. Should have the system installed next week.
To clarify, I’m using 2x of the DALY 200A BMS. Each one will manage 8 cells (2P4S).

Just as an FYI, JBD now has a 200 amp rated BMS that looks quite promising. I have ordered one to test, so far I have found the JBD brand to be accurately rated and trouble free. I have had no problems with the Daly that I own, but many here have.

 

[John Frum]

Just as an FYI, JBD now has a 200 amp rated BMS that looks quite promising. I have ordered one to test, so far I have found the JBD brand to be accurately rated and trouble free. I have had no problems with the Daly that I own, but many here have.

Link please.

 

[Just John]

Link please.

80.91US $ 29% OFF|Jbd Smart Bms 4s Lifepo4 200a Free Bluetooth Heating Function Uart Rs485 Lithium Battery Balance Board Bms 3s 12v With Blancer - Battery Accessories & Charger Accessories - AliExpress

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www.aliexpress.com

There you go. I noticed the reviews start in August, and I hadn't seen it before.
I ordered the model with the "heater" interface, just to test and see how it works.

JBD seems to listen, once their maximum rated BMS was 100 amp, then 120 amp, then 150 amp. I kept pinging them on their Alibaba store (and getting technical details) and telling them a higher amperage BMS would sell well, and they seem to listen.

 

[John Frum]

Link please.

Cool, I like the busbars.
I think one could mount the bms on a pair of these.

https://www.bluesea.com/products/category/28/PowerPost_Connectors?

Here's hoping for an 8s version.

 

[Just John]

Cool, I like the busbars.
I think one could mount the bms on a pair of these.

https://www.bluesea.com/products/category/28/PowerPost_Connectors?

Here's hoping for an 8s version.

FYI, if you buy at least two, they are cheaper here:

Jiabaida 4s Lifepo4 12v 100a 120a 150a 200a Smart Bms With Bt Uart Rs485 Temperature Sensor Heating Function - Buy Bms Lifepo4,Bms 4s,Bms 200a 4s Product on Alibaba.com

Jiabaida 4s Lifepo4 12v 100a 120a 150a 200a Smart Bms With Bt Uart Rs485 Temperature Sensor Heating Function - Buy Bms Lifepo4,Bms 4s,Bms 200a 4s Product on Alibaba.com

dgjbd.en.alibaba.com

Edit to add to the original poster, sorry for hijacking your thread.

 

[Cavendish]

FYI, if you buy at least two, they are cheaper here:

Jiabaida 4s Lifepo4 12v 100a 120a 150a 200a Smart Bms With Bt Uart Rs485 Temperature Sensor Heating Function - Buy Bms Lifepo4,Bms 4s,Bms 200a 4s Product on Alibaba.com

Jiabaida 4s Lifepo4 12v 100a 120a 150a 200a Smart Bms With Bt Uart Rs485 Temperature Sensor Heating Function - Buy Bms Lifepo4,Bms 4s,Bms 200a 4s Product on Alibaba.com

dgjbd.en.alibaba.com

Edit to add to the original poster, sorry for hijacking your thread.

Going to jump in on your hijack.
Has anyone purchased x2 100a BMS instead of 1 200a BMS?
I'm interested as to how one wires them, could someone theoretically use x3 weaker BMS instead of one stronger?

 

[Tim Tim]

Going to jump in on your hijack.
Has anyone purchased x2 100a BMS instead of 1 200a BMS?
I'm interested as to how one wires them, could someone theoretically use x3 weaker BMS instead of one stronger?

If you want to draw up to 200A from say two 12v batteries you can theoretically use a 4S 100A BMS on each battery. Obviously you also have to look at the permissable discharge current for your batteries.