Alt. Problems!!!Not charging...Battery dying...

[SWINGSAX68]

Hey boys and girls...
My alternator seems to be a little fudged.....it works, keeps the charge even when I pull the neg. battery terminal. but it doesn't seem to keep the battery charged after. the battery just goes weak after an hour of haveing my engine on, or just haveing the lights at night when i'm messing with them. And after about a week the battery only has enough to turn her over. My truck isn't drivable yet, could it be that I don't give the alt. a chance to work and to charge the battery???? Hmmmm....
Also, as soon as I turn her on, I never notice how dim the cab light is until I shes all warmed up and I give her more gas....then all of a sudden the light just gets real bright, and stays like that until I turn the egine off. If I let it sit...the light is dim again. Hmmmm ANY help would do guys.

[70c10]

Sounds like it could be a bad ground somewhere. On top of the core support passenger side, remove the ring terminal and bolt and sand down to bare metal for brighter headlights. Also have your battery and alternator tested. I had 3 bad rebuilt alternators before I got a good one. Also my NEW battery had a bad cell in it. Fortunately the replacement alternators and battrey were covered under warranty. You could also be right about not letting it charge long enough. Good luck!

[SWINGSAX68]

I'll try that again.....seemed to work better the first time I did the 'scuffing' but I didn't do a great job of cleaning the ground. I know the alt wires have a ground....lets see there are four wires....black-blue-white-red....the black is ground from something so I grounded it to the wheel well...maybe I'm getting un-needed ground. cause every time I see a truck with my alt set up the black wire is disconnected...just hanging loose.

[Gordo]

Can you get your hands on a volt meter?, (Didgital would be better) if so, attach pos & neg leads from meter to bat posts with truck off and take a reading, you need the batt fully charged to get a accurate alt reading and that would be in the 12.6 Volt range. If it's less than that, recharge batt first. Now that the batt is fully charged, with meter connected, start truck and take a reading, your goal is 13.8 to 14.2 volts running, if it's less you have a charging problem, now to determine what's at fault, the alt or reg. Keep in mine this is for TESTING PURPOSES ONLY! With truck shut down, unplug the reg and use a jumper wire to jump accross the bat terminal and the field terminal (should be marked F & B) of the plug end leaving regulator bypassed, now start truck up, take a reading, voltage should increase to 16-17 volts, shut down truck, alt is good and reg is bad if it read that voltage, if it didn't read that voltage the alt is bad. Hope this helps.

[chevyman 68 C/10]

Could be as simple as neddeing to clean the bat. connections. The alt can be putting out but not able to get into the bat. to charge it up.

A internal regulator charging system seams to charge more at low speeds and is more depedable. It is a good mod. to consider making to these trucks.

GOOD LUCK!