I have a 98 Silverado 1/2 ton and I just replaced the alternator. It was working fine for a while, tested the battery and takes a charge, alternator is charging fine, but if I leave it for a few days without running it the battery does not have enough juice to start. The question is if the battery is weak is there enough draw from the components that are on all the time when vehicle sits to cause this drain.
Thanks

 

When the alternator goes bad it can fry the battery too. You prob just need a new battery now.

 

Thanks, thats what I suspected.

 

no you have to do a parasitice draw test something in you truck is draing you battery the way to do it is pull of the neg battery and hook a ohm meter from the battery to cable if there is any number start pulling fuse by fuse until it goes away then thats whats staying on

 

The radio, security, ECU, and other items depending on the trim package all draw voltage when the key is off.

 

But the reserve capacity on a good battery should handle that drain with no problem. How old is the battery anyways?