In order to protect the battery and prevent overcharging, most solar power generation systems include a charge controller. Its most basic function is to cut off the charging current when the battery is full. The battery type selects the charge controller used. The PWM solar photovoltaic controller uses three-stage charging modes: balanced charge, strong charge, and floating charge.

1. Balanced charge: After the strong charge is completed, the battery will stand for a while until the voltage naturally drops to the corresponding value, and then it will enter the state of balanced charge, so that the voltage at the battery terminals is uniform and consistent.

2. Strong charging: also called direct charging, which means fast charging. When the battery voltage is low, the battery is charged with a large amount of current and a relatively high voltage.

3. Float charge: After the equalization charge is completed, the battery is left to stand for a while, and when the voltage naturally drops to the "maintenance voltage" point, that is to say, the float charge stage, so that the battery can be maintained in a fully charged state without being overcharged.