Modern vehicles have a small but constant battery drain. They are packed full of electrical systems that are constantly working even when the ignition is not running. Alarms, immobilisers, and lock monitoring are examples of systems running in the background that can cause the battery to discharge even when the vehicle is not being used. The OSP500 is a solar powered battery maintainer for 12V vehicles - the low carbon, more environmentally friendly way to maintain your vehicle battery when not in use. Ideal for seasonally-used vehicles such as caravans, classic cars and motorcycles. Supplied with DC power plug and battery clips, works in overcast conditions and is IP 65 water resistant. Reverse polarity protection prevents damage if the clamps are connected to the incorrect battery poles.