I have not tried that yet. It would have to be on the wire leading up to the controller and/or the hot side of the controller itself. That could be a winner. Even with the battery fully charged and the charge booster attached to the battery it is hard to start when the engine is cold.

Almost like the glow plugs are not working.....

Starts great once the engine is warm.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.