Must charge when one of the following conditions occurs: electrolyte specific gravity below 1.2 winter discharge over 25% summer discharge more than 50%; Dim; start weak. Some people believe that fast charge 3-5 hours can save you time. In fact, quick charging is only surface-activated battery quickly, but actually inside the battery is not fully charged. In addition to outside the fast-charging, there is also a slow charge, for 10-15 hours of charging, those dark slow charging the battery must be, otherwise it will directly affect the battery performance. Charge is simple, but there are some considerations: 1. lead-acid battery charging, to wear protective clothing. 2. when charging batteries near Sparks, no smoking. 3. when one or more parallel charging of battery, charger voltage not more than 16V.