Does anyone have any experience with a low voltage disconnect switch such as the Blue Sea Systems-m-LVD? Another is the Victron BatteryProtect. I want to preserve sufficient charge in the battery to start the boat while running the amplifier equipped sound system. The amplifier would be automatically disconnected by the switch when the battery voltage fell below a given voltage. Eg: 12.1 volts. This would be an alternative to a second battery. Another alternative might be to carry one of these small, lithium battery based car starters sold at the auto parts stores. I like the switch idea though. My likely use of the amplifier would be incidental and occasional as it was already on the boat when I bought it.