The Sterling 12V/12V 30A Battery to Battery charger offers quick, multi-stage charging of leisure batteries in vehicles. They are simple to set up and get up and running. This system can provide a faster re-charge of leisure batteries than connecting straight to the alternator and this is essential if you intend to re-charge a leisure battery in a modern vehicle where smart alternators and regenerative braking systems has meant voltage sensitive relays cannot be used in conjunction with this new vehicle technology. This means that they are compatible Euro 5/6 + vehicles that use smart alternators and include regenerative braking systems.