+2 drill battery, but any voltage will work for that. Doesn't have to be 12 or 14v. I've used 18v lithium to test electrics before, surely won't hurt a DC motor for what you're trying to do.

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- Johnny

1990 300D 2.5L - 135k
1998 Jetta TDI - 257k
2005 E500 - 117k