Thats not smoke, its steam. Bring it in next month. We don't work on those. We only do warranty work.
Batteries cause more trouble than any other component in a marine electrical system.
In saltwater areas especially, look for any damaged insulation on battery cables and switch leads, and associated corroded wiring. Undersize wire, loose and dirty connections will cause high resistance, heat at the point of the problem,and voltage drop to your electrical components. This heat will BURN YOU and also destroy your electrical components. Always tag the wires when removing an electrical component. Or just use the secure quick order form to eliminate the cart complexity.