Hi. I have a boat with the following setup: Single outboard with battery isolator which charges the 2 banks separately from the alternator, starter battery and service bank on different main switches and combiner switch in case starter battery dies.
I have a 3 output Phoenix smart charger and 2 outputs are connected directly on the batteries, one on the starter battery and one on the service battery. Combiner switch is off. Smartshunt shows 18amp current consumption and charger shows 20amp charge power. The strange thing is that it also shows a charging current on starter battery which is always almost the half of the service batteries charge current.
Shouldn't the start battery be on float charge as it is not being used and there is no current draw and only service batteries should show charge?
Maybe power from the isolator flows back to the service batteries?