Small and medium-sized lead acid (VRLA, AGM/GEL) can handle high currents during a short period of time. In order to use the battery’s total capacity, the power consumption need to be fairly low. The nominal capacity reproduced normally with 20 hours of discharge and at higher current output ( less time ) , the total capacity is lower. Energy density is usually indicated on 30-50Wh/liter (watt-hours/liter) or 20-30Wh/kg and the nominal cell voltage is 2V. Lead-acid batteries are a cost effective solution and is fairly simple to use. They have no so-called memory effect, they can be charged even if they are not completely empty (discharged), but should never be left completely discharged, then they run the risk of being destroyed within a very short time.