Well not exactly unlimited power, but a lot of power! My wifes lower back is worn out so she can't walk long distances and because not everything is reachable by car we have a foldable disability scooter to overcome that problem. Unfortunately the batteries needed replacement, quite expensive.
The good news is that I now have the old two 12v traction batteries. One can only hold about 60% of it's charge, not of much use. The other is 90%, definitely good enough to use and since the battery is about two times as small as a regular car battery it's perfect for a robot!