Which BMS for 50S Lifepo4 pack.


100 W
Jun 6, 2008
I'm interested in BMS options for a 50S Lifepo4 pack. Nominal 3.3V per cell.

Now I must make it clear.

I am not interested in any BMS with a bunch of large mosfets on the board, as I do not want the BMS directly controlling the load/charge current.

I want simple signal/logic high low outputs/or serial cell data for instance, to tell me about high or low cell V and some on board balancing say < 500ma.

What are your thoughts and recommendations?

I have built my own before but am interested in something commercially available and a lot smaller than my prev efforts.
I'm interested but keener on something already available off the shelf.
Someone on here must be using something suitable. :?
for lifepo4, the D131 has about 160mA balancing current. i split two of them across 87Ah of old rebuilt Ping packs. 24S.

if you used three of the D131 in series you could use the first 2 channels of the third D131 to make a total of 50S.

then connect the signal lines in series from one board to the next. separating the power board from the balance board for the top two BMSs so there is one BMS at the base with all 50S signal lines tied to the output control circuitry which would be on the bottom board. only the signal line of the top two BMS would need to be carried to the bottom.

that would give two extra power boards when they are stripped off the balance boards. then i would connect all three of the power boards together in parallel and allow the control circuitry of the bottom BMS to drive the output mosfets of all 3 power boards. you can even rewire the charging mosfets on the top two power boards to work in parallel with the output mosfets to increase current capacity. that would get up to about 450-500A imo. and 50S up to 72S.

would cost about 160-180 plus shipping. if you added a second set of balance boards to up the balance current to 320mA then they would cost about $45 so about $200 for 450A of output current and 320mA of balancing current. plus henry will allow you to select the comparator parameters for balance and HVC.