Hello. I have a IP22 12/20 blue smart charger with 3 outputs. I have it in a sailing boat connected to 3 batteries, 1 for the engine and 2 AGMs for the 12V interior installation. I have a fridge with a 12V 5A compressor running from this installation. When I'm not on the boat and leave it in the marina hooked up to 220V, I would like to use the charger as a 12V power supply for the fridge so that there is no battery consumption. When I switch to power supply mode, if I disconnect the batteries, the fridge goes off. Is there a way of using it as a power supply even if the batteries are off? Or if I leave the batteries on, will the fridge still be running off the batteries even if in power supply mode and will the charger still be charging them? I'm just trying to save battery life and also for security reasons, I figured that by turning them off or not charging them would be a good solution whilst still being able to use the fridge. My other alternative would be to get a seperate 220V to 12V transformer and plug the fridge into this when at the marina.
Any help or advice would be much appreciated.
Many thanks