Let the sun charge your batteries! This solar charger holds two Rechargeable Batteries of the same type and size (D, C, AA, AAA and Prismatic). It puts out about 150mA and about 5 volts. Many other solar battery chargers tested were unsuitable because their voltage was too low.There is a built-in stand on the bottom of the charger, which can be adjusted so that the charger points directly towards the sun. This will allow you to get the maximum charge rate for your batteries. The meter on the top shows you the current output from the solar panel and the charge progression of each size battery installed. A diode is used to block current when there is no sun so the batteries stay charged. The solar charger will also charge 7 different sizes of Prismatic rechargeable batteries. Prismatic batteries are a fairly new battery used for some mobile devices.The Universal Solar Battery Charger is small which makes it convenient for home, emergencies and outdoor activities.