My charge controller has a second battery charge output but I can't connect it to the starter battery. If I did it would raise the starter battery voltage, thereby closing the split charge relay, and hence connect the starter and leisure batteries, and the two charger outputs.
Instead I use the second charge output to keep a tiny (6Ah) battery charged to run two fridge vent extraction fans. There are lots of combinations eh
Instead I use the second charge output to keep a tiny (6Ah) battery charged to run two fridge vent extraction fans. There are lots of combinations eh