I'm the owner of the battery powered model 40 mentioned earlier in this thread.
I run a deep cycle battery in mine only because I don't use it much. I keep it maintained with a smart charger so I don't get any sulfation when I'm not using it.
I've also successfully removed the battery from my car on one occasion and mowed my front lawn.
I recommend trying a few golf cart shops for a cheap used battery. They are normally in pretty good condition, but if they wont last 18 holes on the course they are no good for them. They normally flog them off for about $20 (but don't hold me to that).
Buying a $100-$150 battery is mental when you compare that to how much petrol that could buy you for a mower.
