Charging LiFePO4 Batteries Correctly

Constant Current Then Constant Voltage

Charge at constant current until the cell reaches its top of charge, then hold that voltage until the current tails off. For a LiFePO4 cell that means charging at 0.2C or 0.5C until the cell reaches 3.65V, then holding 3.65V at room temperature until full.

Normal And Maximum Current

The normal charge current is 0.2C to 0.5C and the maximum is 1C. Our data sheets publish both per model, for example 20A standard and 50A maximum on a 100Ah cell.

Pack Level Voltages

Multiply by the series count. A 12.8V pack charges at 14.6V. A 25.6V pack charges at 29.2V. A 51.2V pack charges at 55V to 56V on our ESS range.

Temperature Limits

Charge from 0℃ to 45℃. Discharge from -20℃ to 60℃ on most packs. Charging below zero is the single most common way an outdoor pack is damaged, and it is a controller setting, not a battery fault.

Storage

Store at around 20℃ in the shipment state. Our data sheets publish a storage window per duration, typically -20℃ to 45℃ for under a month and a narrower band for longer.

What The Protection Board Does

Over-charge, over-discharge, over-current and over-temperature protection with internal cell balancing. It is a backstop, not a charging strategy.