OK, so we jumped the gun, and didn't work on the frame. Instead we did some looking for batteries. I ended up looking at the PowerSonic PS-1270, which seemed like it met our Amp/hr needs, and with 2 of them, we get the 24 volts to power the motors. I just wasn't sure if they could be mounted on their side. The reason I need to know this is that the frame is 3 inches high and these batteries are less than 3 inches wide, which means I could fit them within the frame of the robot. Ryan wanted to buy them right away (of course!), but I said we ought to call PowerSonic to ask. A nice guy answered and said that running them sideways would be no problem, just don't mount them upside down. The cool thing is that he said the PS-1290 was the same size, but in a 9AH, instead of 7! Instant increase in power density is a good thing! I thanked the guy and started hunting for them at the cheapest price. I found them for $23 each at BatteriesASAP.com So, they are ordered and on their way. Now, to find a decent 24 volt charger for these AGM battries.
Oh, anyone know a good source of sprockets and chains? I looked at a bike repair shop, but those sprockets would all require me to machine a hub adapter, since the center holes were far to large for the motor.