My 1977 chevy motorhome acts like the battetry is dead but I just bought a new one.when I try to start it it will almost turn over but not quite. I put in a new battery and starter. It will start right up with a jump. I took the pos batt cable off and ran the heater and lights so it is charging. I am still having the same problem it acts like the battery it dead.

Make sure the cables and their connections are not corroded.