Originally Posted by skiff_life

i ran a trolling motor and depth finder off the same battery in a john boat for years - no problem. I now run a 50 lb. Thrust minn kota and garmin depth finder off the same battery with the transponder mounted on the trolling motor - again, no problem. I would save the space, weight, and hassle of second battery. If you see some kind of interference you can always go to a second battery.