Problems with power
I have a 2001 Dodge Ram 2500 Cummins, and the last few nights while driving my truck I've noticed the headlights dim out every so often and when that happens the battery meter on the dash drops to about 9 or 10 and picks back up after a little bit. Yesterday I was driving around and my check gauges light came on and the power gauge dropped all the way. I drove the truck back home, which was like a twenty minute drive, and it made it without dying. I popped the hood and cleaned all the corrosion off of the terminals and the cables and started my truck. It was at about 12 volts and it ran fine for the rest day.
This morning I started her up again and everything was looking okay for about ten or fifteen minutes and then the check gauges light came on again. I drove it for about fifteen minutes until I noticed all the displays were flashing in and out. So, I pulled over and checked the batteries again. After cleaning them a second time, I could not get the truck to start. When I put the key in the ignition without starting it I got about 11 volts or so but when I tried to start it the truck would click until the power meter dropped all the way again. So I got it jump started and took it to a kragens nearby, like a mile away, and halfway there the gauges light came on again and the power dropped, but I got it there.
So I got the batteries out and took them into kragens and they tested them, Both batteries were in okay condition and I had them charge them for me. The batteries are old as shit, seeing how I have not replaced them and I've had this truck since either 2003 or 2004, but the guys at kragens said I should be able to putt around town with them. So I put the batteries in and the truck stated fine but after about five minutes or so in the parking lot the gauges light turned on again and the displays stated flickering. I asked someone inside if they could take a peek at it, so we started it and they checked the battery power and he said they were low but they were okay. I let the truck run for about ten minutes and decided to take her home.
On the way home, probably like 10 minutes in, the gauges light came on and the power dropped again. So I dragged it home and turned it off. I immediately tried to turn it on and it worked, with the power meter being up at like 12 volts or so. So I have some questions.
1. I know the batteries are super old and way past their prime, do you think it is the batteries?
2. Is the alternator jacked up? I blew my turbo out about a month ago and it blew oil everywhere and I tried to clean it up the best I could but the alternator is dirty than shit, could that have something to do with it? I wouldn't think so because it has been running fine for a month and I figure the dirt would have not made it work right from day one if that were the case.
I'm not sure what to do here. It looks like replacing the alternator will be cheaper than buying two new batteries, but the batteries are easier to replace. It's like the alternator is not charging the batteries while I drive, so that makes me believe its the alternator, but then again after draining the batteries while driving I can get tuck to start up again sometimes with 9-12 volts. Any help or ideas would be greatly appreciated.