What truck? Year and brand? I've done it before and my dad before me. The regulator controls the generator or altenator, and nobody I know have ever had a problem. We use to do it all the time to get another car started. Drive one car there, leave it running, take the battery out and put it in the second car, and drive them both home. When in high school we didn't always have jumper cables and didn't always have room to push start.[altho I don't remember why not], but we did have tools most of the time. None of us ever had problems on any of the cars for the many years we owned them.

And sometimes the engine wouldn't run unless the batt cables were held together and tied for the trip back.