The GOLABS R300 can be charged using a variety of methods, including AC power, car charger, and solar panel. The charging time varies depending on the method used and the amount of power remaining in the battery. When using an AC adapter, the R300 can be fully charged in about 7-8 hours. When using the GOLABS SF60 solar panel, the charging time can range from 7-9 hours depending on the amount of sunlight available.