DC-DC Chargers are perfect for vans, motorhomes and boats as they charge your batteries while you move. Placed between your vehicle’s starter battery (which is connected to the alternator) and the leisure batteries, they monitor the input voltage from the vehicle alternator and once a certain voltage range is detected, they will start drawing power to charge your leisure batteries. The built-in engine shutdown detection will stop the converter when the engine is not running, preventing unwanted discharge of your starter battery.

They are a premium alternative to split charge or voltage sensitive relay devices which do not work well with ‘smart’ alternators present in most Euro 5/6 engines. 

Isolated or Non-Isolated? The main difference is the method of electrical isolation between the input and output circuits. Where you have a common ground connection (negative) between the two voltages, a non-isolated DC-DC charger is usually suitable. The non-isolated chargers are less-expensive, but if you require electrical isolation or protection against voltage spikes you will need the isolated charger. Please consult Victron or a qualified electrician if in any doubt about your requirements. 

How to work out the size? The first two numbers (e.g. 12 and 12) refer to the starter battery voltage and the leisure battery voltage respectively. So, both these chargers are for a 12V starter battery and a 12V leisure battery. The third and final number refers to the maximum charge current which is 30 Amps - and indicates how quickly it will recharge your leisure battery. For even quicker charging you are wire two chargers into your system to gain an effective 60 Amps of charging current.