I must echo the thoughts of the others

the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCUC2&P=0]Chrome top box with the Single motor 12volt motor [/link] will be much more reliable
the battery is only $20 at most hobby shops, [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL370&P=M]tower has them for $18[/link]

A nice bonus to having the 12 volt battery in your box is you always have a 12 volt power supply to charge your Rx/Tx with at the track. When I go to the track I take a fully charged Starter box, and my [link=http://www.hitecrcd.com/Chargers/Discontinued/CG-335pro.htm]Hitec 12volt feild charger[/link], that's all I need. I really don't need any AC power at all to run a full race day