My parents don't ask anymore.

Ok batteries, you have a number of options.

- SLAs - very old school. You would be looking to the batteries designed for alarm system back ups. I wouldn't even bother if I were you though, heavy and difficult to get current out of.

- Nimh/nicad racing packs - I think this is probably your best bet. Two 7.2V packs in series will happily run your drive plus axe mechanism.

- A123s - This would require you to build your own packs from cells. A 4 or 5 cell pack would happily run your machine and provide you with higher currents.

http://cgi.ebay.co.uk/10-Pcs-New-A123-3 ... 2a01f91692

Not too difficult to build your packs if you follow the information provided by John Reid on the terrorhurtz site.

- Lipo - I wouldn't bother. You won't need the currents these can provide and they're pricier.