I tried the same idea using 12v coiled cigarette lighter extension cord. Unfortunately the cord was incapable of providing enough current draw and could barely move the motor. Admitely I was using a 3 foot section as an external battery connection so length coupled with the thin cord could have limited the ability. So, just a heads up that coiled cord for lighter extensions probably just isn't enough. Perhaps you can find some heavier thicker cord than I was able to.
-Daes-