have you put a volt meter on it to read the voltage at those various conditions?

 

I know my dad had problems with an old pontiac one time and it was from the starter getting hot and making it drag. But like you said that is probally not your probem.

 

i had a similar problem ALONG time ago with my mustang... come to find out the power wire for the starter was grounding against the header.... So when i would go to start it, sometimes it was fine other times it would drain the freaking battery due to it grounding out... So maybe look over all your power wires, and make sure it is not grounding out somewhere.

 

Take the truck to the auto parts store and have then test the alternator - I know you just put it in, but when i used to manage the local Advace auto store the kids working the weekenly inventory shipment would start throwing/sliding parts across the store.

With this being said I always double check my parts when i buy them now bc of this. It almost sounds like the diodes may be dead in the new alternator.

 

Bypass it and see what happens...

 

Red top optimas are JUNK!!!

The older one are great, but the newer ones advance auto sells are junk.

If you get an optima make sure its yellow top, they are still great batteries.

I'd chuck that red top and get a good battery. Could be an internal short in the battery.

 

Turns out it was my battery cutoff switch. Don't know the reason why, but I bypassed it and haven't had a problem since

 

good to know man. thanks for updating this thread..