I need to look into them, I have the Blue Sea ML ACR but only charges when the car is running. I can switch it over to charge full time but not comfortable doing that when I am not around.Have you looked into the redarc dc-dc charger? its a really good solution to keep both batteries fully charged. it is a charge controller that will adjust charging voltage based on type of batter and is also a multi stage charger. supper easy install and has some other features you might or might not need IE solar charge controller.