I have a 2000 Silverado 1500 with 4.8. over the last couple years I have been having a problem with my battery slowly discharging over a month or 2. I replaced the battery about a year ago when I had to get a hotshot figuring the battery was the problem since it was 4 or 5 yrs old. after a couple months I had the same problem, the battery would get low enough where it almost wouldn't start or I would have to get a hotshot. this happens every month or 2. I don't use the truck a lot, only to pull my boat in the summer and to go to the dump. I checked the output at the battery. when it is cold and idling high, the output is 14v. when it is warmed up the output is 12.4 v with the lights off and 14.2v with them on. Can my alternator just not be putting out enough volts? when I'm at the dump unloading, I leave the truck running. last time I did this, I went to the store right after and when I came out, I had to get a hotshot. but, after I drove home, the battery was charged enough to start the truck. The truck battery doesn't lose a charge when it is sitting. I guess my question is, is 12.2v at idle charging too low? do I need to replace my alternator? driving along with my foot of the gas pedal, my lights are considerably dimmer.
any thoughts?

 

14v sounds good; how often do you drive your truck?

 

I meant to type 12.2v with lights on. I only drive the truck 4-5 times a month