I have a problem with my 1994 silverado truck
the truck is slowing losing the battery charge
now if i leave overnight i will have to charge it or jump it
before it would take two weeks before i would have to charge it
to me it seems like i have a draw somewhere, i don't know
if i pull the neg. post off the battery while it is running it still runs
and i checked the alternator while it was running and it checked out at just over 14 volts
but when i check the battery with it connected it checks out at 13 volts +-
if i turn on everything on the vehicle (lights, radio, a/c, etc) it checks out at just over 12 volts

 

Have the battery load tested ... it may not be able to hold a charge.

Or try this proceedure from this other post : https://chevroletforum.com/m_11221/tm.htm

 

You might have a bad positive post or a loose connection on the battery. I had that happen on my '97 k1500 - sometimes it wouldn't start, sometimes it would die while I was driving it. One day, the wire fell off the battery with the post still in it. Oddly enough, I had the same thing happen on my '02 k1500HD. It would need to be jumped every once in a while and one day on the way to work all the lights inside were flickering, got to work, shut it off, no power. The wires on the positive post felt just a little loose so I went to tighten them and the whole post just came off. New battery - no more problem.