Four Concerns About Lithium Battery Charging

When to Charge the LiFePO4 Battery?

Generally, LiFePO4 batteries do not need to be charged after each use if they are not fully discharged. LiFePO4 batteries would not get damaged when left in a partial state of charge. You can charge your LiFePO4 batteries after each use or when they have been 80% discharged. Please note that we recommend storing batteries at 50% state of charge (SOC) to minimize irreversible capacity loss. 

Can LiFePO4 battery be charged in cold weather?

The recommended ideal charging temperature for LiFePO4 batteries is between 0°C to 45°C, which can best guarantee the battery to be fully charged to 100%. As your actual weather condition is extremely cold at a temperature below 0°C, we recommend reducing the charge current as follows, until the temperature is >0°C. 

1. Temperature 0°C to -10°C, charge at 0.1C (10% of the battery capacity) 

2. Temperature -10°C to -20°C, charge at 0.05C (5% of the battery capacity) 

Polinovel LiFePO4 batteries come with a BMS that protects the battery from over-temperature. If the BMS disconnects due to high temperature, wait until the temperature reduces and the BMS reconnects the battery circuit before using or charging the battery. Please refer to the exact battery datasheet for more value.

What is CC/CV charging? 

This is the most common charging method of lithium batteries, CC refers to Constant Current and CV refers to Constant Voltage. The Two-Step Charging profile can charge lifepo4 battery 100%. Detailed charging process is as follow: 

Constant Current Charging (CC) 

The battery is charged at a constant current until the voltage reaches the absorption voltage. 

Constant Voltage Charging (CV)

Keep charging the battery at a constant absorption voltage until the current reduces to termination current.

For the constant current, absorption voltage and termination current, please refer to the below chart: 

How to charge series or parallel lithium battery system?

If you are going to connect batteries in series or parallel, please make sure the battery's voltage is on the same level before putting them into use. The voltage of batteries should be within 50mV of each other, this will minimize the chance of imbalance between batteries. If batteries get out of balance (>50mV), each battery should be individually charged to re-balance. Note that each battery voltage is within 50mV of each other before putting them into use.