The process of charge and discharge of lead-acid battery is the process of electrochemical reaction. When lead is charged, lead oxide is formed, and the lead oxide is reduced to lead sulfate when discharged. While the lead sulfate is a very easy crystallization, when lead sulfate concentration of electrolytic solution in the battery is too high or the static idle time is too long, will "hold" group as a small crystal. These small crystals of lead sulfate attract around, like a snowball formation of crystalline inert large, lead sulfate crystallization after charging not only can not be reduced to be attached to the precipitation of lead oxide, electrode plate, electrode plate caused a decline in the work area, this phenomenon is called vulcanization, it is often called that the aging. At this point the E-bike Battery will gradually decrease until it is unusable.