Yah, he was just running a 12V bilge pump on a battery, and used a charge controller to keep the battery up so just needed a voltage slightly above the battery voltage. I doubt it used a kWh per day as it cycled. He might still be using it, haven't talked to him in a few years.
[0] https://user.physics.unc.edu/~deardorf/phys25/rwp/exam1rwpso...