Bob,
Sounds like you may have a problem with your connections. Your losing current through bad/corroded connections I think. When you put additional current in from a running vehicle it pushes through the bad connections anyway. Clean all of your connections from the ground and hot on the battery up to and include a good cleaning on your starter posts. This should take care of it.
Sounds like you may have a problem with your connections. Your losing current through bad/corroded connections I think. When you put additional current in from a running vehicle it pushes through the bad connections anyway. Clean all of your connections from the ground and hot on the battery up to and include a good cleaning on your starter posts. This should take care of it.