LifePo4 Charge Performance

3 tons wrote:
The primary function of the BMS is to avoid catastrophic events and to perform individual cell balancing - the BMS does not govern charging amperage, and for some manufacturers serves as a low temp charge disconnect.

3 tons

only if your talking the cheep 15 to 30 buck ones. see below ;)

BFL13 wrote:


With LFP they talk about resting the battery after a full recharge so it works best on the next discharge. It is not clear it has to do with balancing or just how LFP cells work.

I don't see where BMS controls the charging current, even the expensive ones. they do have cut-offs for excessive currents and voltages, but I don't see where they "dial" the current to match the acceptance rate at various temps and SOCs. Seems like that is up to you not to use a charger that cranks out too many amps.

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when you buy a BMS it is rated for a spicific amprage which designates it discharge and charge rates. it is internaly part of the BMS , so part of building a LFP set up is knowing how big of a system you are building and how many amps you want to limit your draw to, and then buying the BMS that meets your needs. they range from 50 amp (well probably smaller but I haven't looked at anything smaller) to 400 amps for the ones I have seen. some have bluetooth so you can customize the different settings and monitor, some don't. some have passive ballancing, some have active ballancing, some have low temp charge cut off some don't. so if you have a charger that puts out 75 amps but your BMS restricts to 50 amp charging then all you will get is 50 amps to your batteries. its all done internaly and that part is not adjustable you have to buy the right one for your application.

here is an example of a good one. it will only allow 120 amps charge or discharge, but that is per battery so if you build two batteries you will be able to putput 240 amps, three batteries 360 amps and so on. there are bigger BMS from other companies this one just focuses on this range.


Steve