[mr48chev]

The positive cable can feel real hot and even burn up if the resistance issue is on that side going to the starter or what ever else you are having an issue with.

in 58 years of working on cars and trucks I have far more bad connection issues on the ground side than the hot side. Guys usually pay very close attention to connecting the hot side from cable end to the starter. They often ten to be lax on the ground side.

If the "hot" cable is hot that usually means that what ever you have an issue with be it starter or light or what not is defective in one way or another. I say HOT side simply because we do have rigs with a positive ground electrical system including 6 volt GMC Trucks.

Still it is never assume, in that you always need to inspect and test rather than assume.

This is a case of that. Just because the truck fires up at home and then doesn't want to crank 30 minutes and three miles later doesn't mean it isn't charging, The starter could have bad bushings and be dragging. The battery may be marginal and won't crank the now heated up with engine heat starter. There may be a resistance in a connection.

I fought my 77 for a long time and even replaced the starter when it wouldn't crank when hot and finally changed battery cables to larger diameter cables to fix it. The skinny cables wouldn't carry enough amps to crank it over good.