LifepO4 battery recommended max charge current in a series-parallel connections

[fabieville]

I have (4) 24V 100AH Redodo Lifepo4 battery that i connect in series-parallel connections to give me a total of 48V @ 200Ah to power my 48v system that I have. Each of these battery contains a BMS that the manufacturer supports a recommended max charge current of 50Ah.

What i want to know is due to the fact that its (4) separate BMS in my battery bank if I decide to charge the pack with 200Ah would it be automatically shared between all 4 BMS so basically each BMS would be drawing about 50amp? So in that case I would be able to pump that high 200Ah tru the bank and don't have to worry that one or some of the BMS might be drawing more than 50amp?

Or due to the fact that my bank is rated 48v @ 200ah should I limit the charging current to 50% of my battery bank which would be 100ah the max charge current that should be going to the battery bank?

[jflorey2]

I have (4) 24V 100AH Redodo Lifepo4 battery that i connect in series-parallel connections to give me a total of 48V @ 200Ah to power my 48v system that I have. Each of these battery contains a BMS that the manufacturer supports a recommended max charge current of 50Ah.vWhat i want to know is due to the fact that its (4) separate BMS in my battery bank if I decide to charge the pack with 200Ah would it be automatically shared between all 4 BMS so basically each BMS would be drawing about 50amp?

You're confusing AH (capacity) and A (current.)

If you want to charge 4 batteries in 2S2P with 200 amps, and they divide perfectly, you will get 100 amps per string. And they never divide perfectly.

I would not go over about 80 amps with that setup.

Also be aware that those batteries have no way of balancing outside the string, so you will have to continuously monitor voltages at the midpoint.

[SunEagle]

I have (4) 24V 100AH Redodo Lifepo4 battery that i connect in series-parallel connections to give me a total of 48V @ 200Ah to power my 48v system that I have. Each of these battery contains a BMS that the manufacturer supports a recommended max charge current of 50Ah.

What i want to know is due to the fact that its (4) separate BMS in my battery bank if I decide to charge the pack with 200Ah would it be automatically shared between all 4 BMS so basically each BMS would be drawing about 50amp? So in that case I would be able to pump that high 200Ah tru the bank and don't have to worry that one or some of the BMS might be drawing more than 50amp?

Or due to the fact that my bank is rated 48v @ 200ah should I limit the charging current to 50% of my battery bank which would be 100ah the max charge current that should be going to the battery bank?

A battery with a separate BMS needs to charge separately. The way you have them wired those 4 will never get the proper balanced charge

[fabieville]

I realize i connect them wrong so i rewire them as 2P2S. (2) 24v 100ah in parallel and then a next (2) 24v 100ah in parallel and then i connect them in series to have 48V 200AH when i test each side of the pack i am getting the same voltage reading now. So will they charge better now? or will they become unbalance in the future which will require a separate 24v charger connected to each side to charge up each side until they both reach 29.2V?

[SunEagle]

I realize i connect them wrong so i rewire them as 2P2S. (2) 24v 100ah in parallel and then a next (2) 24v 100ah in parallel and then i connect them in series to have 48V 200AH when i test each side of the pack i am getting the same voltage reading now. So will they charge better now? or will they become unbalance in the future which will require a separate 24v charger connected to each side to charge up each side until they both reach 29.2V?

Anytime you wire batteries in parallel you run the risk of different resistances in the lines which results in different charging amps. The more parallel runs the higher the chances of not getting even charging. Your system may work out and then again one of the four batteries may not stay "happy" and fail earlier then the others.

[fabieville]

My battery bank is a Redodo and I currently have (4) 24v 100Ah batteries string as 48v 200Ah 2P2S connection and the manufacturer told me this:


If you only charge it to 90% SOC， it is recommended voltage after 30 minutes of resting after charging is completed is: 13.6V-13.7V .
You are really right. The difference in batteries will get bigger and bigger during the use process, so it is recommended to balance them every 6 months for better protection and longer use time.

If you discharge them to 50% and then recharge them, the experience of using the batteries is very poor, it is recommended to discharge to 10%-20%, if 20%, the battery will have better lifespan and performance.



With this info about is this really the case? I thought discharging only to 50 r 40% would give me more cycles? I didn't know that not going down to 20% would affect my performance and lifespan. Is this true because I don't see this online when i do a lot of research.




Also redodo states that their BMS starts balancing at 3.5v so with that case do i have to charge up to 56v each time or should i do a safe bulk charge of 55.2V and then maybe do a manually charge of each battery every 6months to the 56v or full charge voltage to get back all batteries internal cells in a balanced state and each batteries reading the same voltage before i reconnect them back in 2P2S?