BatteryIndicator work theory:

There two balls in Two colors. The red and green gravity balls are used for the battery indicator. The gravity corresponds to cristical density of battery electrolyte, when it Works, either ball sinks or gloats, leading to different indicators, meaning to Indicate different battery states.

Battery indicator Usage:

Battery  Charge indicator can do detection of Electrolyte level and charge efficiently. and it is good for increasing Efficiency in the process of transshipment and warehousing, and using it could Reduce the cost of detection about 90 percent.