All batteries have a C-Rating that we refer to for charge/discharge values.
LFP cells in general, have a 1C Rate for Discharge and a 0.5C Rate for charging.
A 200AH LFP cell (not battery pack but individual cell) can handle a 1C discharge rate which is 200A output and a .5C rate or 100A Charge Input.
If a battery pack (complete assembly) is built with Genuine 200AH cells, the complete battery will operate with the limits on the line above.
If a Battery is built with 100AH cells that are paralleled THEN the Discharge Rate will be limited to 1C/100A and the charge rate will be .5C/50A.
Yeah it is a bit confusing at first blush ! There is a LOT of info to absorb and sadly a gotcha in this, is that FLA (Lead Acid) battery language is similar, it is not the same exactly. This ultimately creates confusion as terms are applied differently. I really had to wrap my brain around that because I started with big Lead Acid and now also have a large LFP bank as my primary.
These older generation batteries are likely fine BUT one thing to be certain of with such prebuilts, be "conservative" and "reasonable".
Charging these, the profile should be "modest" so as to not stress or push the battery pack.
You can push up to 50A charge rate at the battery but NOT more ! Conservative would say limit that to 40A.
The working Voltage Curve for LFP is 3.000-3.450V per cell. So for 12V system 12.0V to 13.8V which is just a hair over 90% of total capacity.
The functional voltage range is 2.500-3.650. LFP will always settle from 3.650 to 3.550 within an hour on average. This is normal.
• Bulk/Absorption: 14.0V (3.500 vpc)
• Absorption Time: 15 minutes per 100Ah of battery bank
• Float: 13.4V – 13.8V (3.350-3.450 vpc)
• Equalization:
Disabled
• Temperature Compensation:
Disabled
* vpc = Volts per Cell based on standard rules.
** It is often said that FLOAT is not needed or wanted. Float is NOT topping the cells at 100%, it is Constant Voltage and floating current, this is used by the BMS during it's internal balancing process as it sits, this allows the cells internally to all level up identically. This also compensates for the bit lost during Passive Balancing which only burn off hi voltage. Not all BMS' have such capabilities but I recall that the AmpereTime had passive. (could be only certain models, can't say for sure)
Inverter Cut Off points should be 10.4V (2.600vpc) for Low Volt cutoff and 14.4V (3.600vpc) for Hi Volt cutoff. Same applies to other gear like SCC etc.
See the link to the LFP Voltage Chart in my signature.
You have not mentioned with WHAT you are charging. Do you have an Inverter/Charger, an Inverter & separate Charger or what. You CANNOT use a 12V port from a genset to charge such a battery ! Few tried and it never ended well. DO NOT USE a Car Battery Charger ! NEVER !!
A VERY IMPORTANT POINT which is often neglected.
Any Lithium Battery system is far more sensitive than the old abusable Lead. You will see how I note 2.600v or 3.450v per cell, it is because it is THAT sensitive. Yep, millivolts add up and fast. Also realize that 90% of the AH Stored sits between 3.000-3.400vpc. Ensuring that the system is clean & calibrated is essential so that things do not go wrong.
All Lithium is intolerant of any abuse. What this means, is when you setup your Inverter/Charger and other devices, you will have to correct & calibrate the voltages so that when the Inverter sees 13.900 that it really is 13.900 and NOT 14.2 because there is line loss and it will overrun the battery.
- See link in my signature regarding Calibration. You'd be surprised how many do not do it and wonder why things go kaflooie in the worst of ways.
Think of it this way: Old Lead Acid was abusable and tolerated a fair bit actually BUT it is considered "Analog Tech". Lithium Systems are the next generation and "Digital Tech" and as such far more sensitive to things like voltage deviations etc.
Hope it helps and answers your questions without too much confusion.
Sorry, I prefer to provide a more detailed response because who knows who will be reading the thread later and what their knowledge/experiences are.
BTW: Highly suggested Reading:
https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/