lifepo4 pack balancing with bms

[melcoeb]

Newbie here.

I have 16 Eve 3.2v 100ah cells. Battery balancing, from what I've read, is a must. I plan to balance 4 cells at a time. I've seen (yt) that I need a 4s 12v bms to charge to safely get close to 3.65, then use dc power supply to get to 3.65.

Question is on the 4s bms: do I need to get a matching 4s 100a bms (to match 100ah of the battery) for this, or will a 4s 20a be good enough?

Appreciate all responses, thank you.

 

[sunshine_eggo]

Newbie here.

I have 16 Eve 3.2v 100ah cells. Battery balancing, from what I've read, is a must. I plan to balance 4 cells at a time. I've seen (yt) that I need a 4s 12v bms to charge to safely get close to 3.65, then use dc power supply to get to 3.65.

Question is on the 4s bms: do I need to get a matching 4s 100a bms (to match 100ah of the battery) for this, or will a 4s 20a be good enough?

Appreciate all responses, thank you.

What is your final battery config?

The BMS only needs to be rated for the currents in and out of the battery. If using a 10A supply, 20A is adequate.

 

[melcoeb]

Final constructed battery config will be 48v 100ah, 16s. Final BMS will be 16s 100A.

For the initial balancing of the 12v 4 pack, I will use 0-30v 0-10a dc power supply that will be connected to the 4s 20a bms.

Thanks for your reply.

 

[sunshine_eggo]

Final constructed battery config will be 48v 100ah, 16s. Final BMS will be 16s 100A.

For the initial balancing of the 12v 4 pack, I will use 0-30v 0-10a dc power supply that will be connected to the 4s 20a bms.

Thanks for your reply.

IMHO, don't buy extra hardware.

Wire 16S battery w/BMS

Charge the 8 cells from the negative THROUGH the BMS to cutoff.
Swap cells 1-8 with cells 9-16.
Charge the other 8 cells from the negative THROUGH the BMS to cut off.

You will be able to charge half the pack at a time @ nearly 300W vs 1/4 the pack at 150W max for a 15 minute "cell swap" operation.

You would charge between the two arrows:

Depending on the BMS, you may need to increase the delta-V value to something like 0.5V.

Charge 8S between the arrows indicated:

 

[melcoeb]

got it. thank you.