With light surge protection to avoid the storage battery being over charged or over discharged .
The charging way turns into electronic pulse automatically. The currency is related with the intension of the sunshine.
The circuit turns into sleep mode automatically when system stop working or entering into surge protection mode. But it is necessary to charge every 3 months.
Maintenance-free storage battery stops us from the trouble of adding water on time. It can keep on work under great windy circumstance.