UPS usually use maintenance-free sealed lead-acid batteries. The physical and chemical properties of this battery make it almost no water loss when in charge and discharge, so it needn't to add water, it can be placed arbitrarily and no corrosive gases due to its sealed structure, no maintenance troubles. The standard battery voltage of 2V, 4V, 6V, 12V, the most commonly used for UPS is 12V. If a battery voltage is not enough, put multiple battery in series, that formed battery pack. Notes: the life of maintenance-free sealed lead-acid batteries is closely related to the using method and environment, people should pay attention to the following points:

1. it cannot be long-term storage and out of use, that will make the battery lose activity, eventually leading to failure.

2. the suitable environment temperature of battery is about 20 degrees ,higher than 40 degrees will shorten the battery life and under than zero the effective capacity will decline.

3. people should charge in time after deep discharge, always deep discharge will influence the battery life.

4. over discharge (discharge below the rated voltage of the battery) is harmful to the battery.

5. the reliability of chargers and appropriate charge ability is essential to the life expectancy.