3, battery, solar street light now commonly used with gel battery and lithium battery, battery, although the price of gel battery than lithium battery low, but the service life of the gel battery than lithium battery low a lot, now the domestic use of gel battery service life is no more than 4 years, and lithium battery is the minimum service life of 5 years, so a lot of local solar street lights for 3, 4 years later not bright, largely because are gel battery service life is shorter.