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How to charge LiFePo4

LiFePO4 does not need a multistage charging profile.

The manufacturer of our 100 ah cells, and the MFG of the common 280ah cells specifies charging at a rate of 0.5c up to a maximum voltage limit of 3.650 per cell.

Based on the LiFePo4 charge curve the cells will reach nearly 100% charge at 3.500v per cell, so this is our recommended target voltage (14.0v per 4-cell battery, 28v per 8 cell battery).

Note that there is no mention of “float” charging. This is only applicable to lead acid yet most charger designs include a float setting for LiFePo4, usually 13.2v for a 4 cell battery.

Why is this a problem? Because at 13.2v the battery will be significantly discharged, and so you will observe the battery going through a deep cycle after every full charge, even though it remains plugged into shore power.

Therefore the ideal charger for LiFePo4 batteries (in our opinion) is a current limited power supply set to 14.0 to 14.2 volts.

4 thoughts on “How to charge LiFePo4

  1. Does C rate of charge matter other than how long it takes to charge? I have a 16S/48V setup with 280Ah batteries, and it is not easy to charge at 0.5C, which is 140A. Is there an issue if my C rate of charge is, say 0.1 or less? I haven’t any panels yet and I’m using a power supply. Your BMS is also just 100A. Must I charge them in groups of 12 volt or 24 volt? Thanks for any help.

    1. A slower charge rate is always acceptable. The quoted C-rate is the upper limit.

      You will need a charger for a 48v system. The upper limit voltage should be set to 56.8v.

  2. Generally a charger will stop charging at .05C (5%). That would be 14 Amps for a 280Ah battery. What happens if my solar panels are only charging @3-5 amps, won’t this overcharge the battery?

    1. Hi
      Do you mean “under charge” the battery?
      Since you said the charger would stop at 14 Amps and then you stated your panels only produce 3-5 Amps. Since 3-5 is less that 14, wouldn’t that mean the charger would not charge… “Generally a charger will stop charging at .05C (5%)”
      Thanks, just learning this stuff and a bit confused

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