The so-called floating charge means that in the AC power supply/battery power supply system, the rectifier and the battery are connected in parallel to the feeder. When the commercial power is normal, the rectifier supplies power and also provides a small amount of supplementary current to the battery. This power supply mode is called floating charge, and the voltage output by rectifier in this process is called floating charge voltage.

Because the products of different manufacturers are different, the floating charge voltage is slightly different. Generally, each battery is 2.23-2.27 V (at 25 degrees Celsius), and the 6v battery is 3, so the floating charge voltage is 6.69-6.81V. The so-called uniform charge, that is, balanced charge, is to charge the battery with a fixed current and a fixed time, which is faster.