Could you be a little more specific when you say your battery “loses charge”? Does your boat develop symptoms, or are you referring to actual voltmeter readings at specific intervals during and after the charging process? Two other possibilities other than parasitic drain are a charger issue or a battery issue. As far as a separate battery on/off switch, John Jones thinks that they are a good idea for the cranking battery, Here is a quote from him a couple of weeks ago on a thread involving installing one.JonesTrollingMotor, , #7, [-], ||Posts: 289Feb 16 15 10:09 AMReply Quote MoreMy Recent PostsMessage MeBlockingIgnore Users Posts, Nice clean looking install. In my opinion, a battery cutoff switch should be on every cranking battery, and on the positive wire of the trolling motor battery.John, ||