These lights were used as spotlights/floodlights (probably for bow fishing - don't laugh, it's very popular here in Bama) and not for running purposes, so they probably required a great deal of power to run for hours on end. I am thinking he connected them to the trolling batteries in parallel fashion because he would rather run those down and recharge between trips rather than risking running his main down and getting stranded on the river/lake. I heard it is not good to recharge your main but I don't know for sure. At any rate, I won't be using these types of lights while fishing at night, so it's a moot point for me. The only thing I have connected to my trolling motor is one Group 27. Everything else is connected to my main.I've used a light fishing before out on the gulf. It draws fish to the boat. Never tried it in fresh water though.