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?

[joestue]

In theory with your series parallel connection you can charge your 48v pack at 100 amps. Not amp hours. In reality there may be 40 amps into one battery and 60 in the other, although i hope they are much better balanced. In the event one bms open circuits to protect overcharge, the other will quickly follow.

If you re connect all 4 in parallel you could do 200 amps at 24v.

[fabieville]

I rewire my bank to 2P2S.

Suppose I decide to get (2) 24V Lifepo4 charger and connect them.to each side of the series connection do u think it would charge each of them to 28.8v so that all batteries would be reading the same voltage whilst still connected in the parallel-series connection? This charging would take place once every couple months just to bring the SOC and voltage reading close as possible and i think i would let this occurs only when the outback mppt has reach 54.6v or near a full charge so basically when the charge controller reaches 54.6v and begins to float charge then the 2 chargers would commence charging of each side of the battery pack of so that there won't be any voltage difference between them or the most would be 0.01v at the end of the charge cycle. I would only do this when i notice a voltage difference between the 2 sides later on in the future as i don't expect to see it anytime soon because i have been using the batteries over 3 months now and the 2 sides are still showing the same voltage reading.

I would go with either a 1 or 2 Amp 28.8v Lifepo4 charger

Can this method work?

[joestue]

the bms should have resistors which discharge the high voltage cells.. before the bms open circuits to protect the battery.

so it should "just work" if the packs are all equal.

[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?

[DamonHD]

My rule of thumb when I had LFP and lead acid in my tiny off-grid system was that the former prefer to be nearly empty and the latter nearly full (most of the time).

Rgds

Damon