Normal service life in1~5 years, the consumption of electrolyte is very small, in the use of the basic need not add distilled water. It also has the characteristics of high temperature resistance, shock resistance, small volume, small self discharge. The service life is two times of common battery. Market maintenance free battery has two kinds: first at the time of purchase disposable add electrolyte after use does not need to maintain (adding and supplementing the liquid); another is a battery factory has increased the electrolyte and sealed, users simply can't add supplementary liquid.