OK, I haven't had one of those but I did have an older microprocessor-controlled battery switch, which was noisy. This one isn't part 15 compliant if it is noisy, you should tell the manufacturer that their product may be out of compliance and should have their products evaluated by a testing lab because it is illegal to sell a product that isn't compliant. If they give you crap, I would shoot a complaint at the FCC site.
Know this is an old post but switched to a Kisae technology dmt1250 50 amp dc to dc charger/maintainer for the deep cells and couldn’t be any happier.
