My old batteries weren't lasting a full day on the lake, so I just bought a pair of new Basspro XPS Deep Cycle 175s for my 24V MotorGuide. They took about 24 hours to charge with my little on board 5/5/5 amp Basspro XPS charger, and when they were done charging, the trolling motor wouldn't turn at all. After trying a few things I put the old Interstates back in, and now those won't turn it either.

I took some readings with a multimeter, and I get 28.2V and 2.9A at the trolling motor plug, but when I press the switch on the trolling motor, it drop to 6.3V and 0.3A. Is this an indication that the batteries are not charged, or that the trolling motor is shot?

Your batteries are in good shape. The problem is with your trolling motor.

Thanks for the info. I was afraid of that. Nothing like having your trolling motor break 2 days before a big trip. I guess this is why the pros have backup trolling motors right on the boat.