Bought one these simple battery boxes to chuck a battery in for the fridge and lighting etc. Promised I would keep it simple.......
I had a box electronic goodies and spare parts just chillin in the shed, so a few hours later........
Testing charging -
100ah AGM battery, 3 x cigarette lighters with resettable circuit breakers, 2 x USB charging sockets, high amp input/output with isolator switch and flashing 'Live' warning red LED for jump starting or high current appliances, 50a Anderson charging or power supply plug with circuit breaker, LED voltage gauge and illuminated power switch for the sockets. I have also calibrated the voltage gauge on the box with a multimeter so it is spot on accurate, and also volt drop compensated the aux battery voltage gauge I have mounted up the front of the Vitara to allow for the small amount of resistance in the dual battery cable. So now the meter on the box in the back of the Vit, is within 0.1v of the gauge up front. I also have a main battery volt meter on the dash so I can gauge the charge of the second battery.
Should get about 4-5 days of run time out of the fridge without charging.