Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Unknown electrical issue - Battery not charging but holds charge

Hey all, Need to make sure im covering all my bases when I start this diagnosis.

I started my truck this morning, nothing special. Checked my voltmeter, battery is sitting low, which is normal because it usually rises after starting.
My voltmeter goes from 8-18 red on both sides of that, and has normal in the center. Usually when running it sits at “L” now it sits at “N” on normal
So I sit and watch it, nothing happens, first thought is my gauge is funky. Turn the truck off, turn it back on and it struggles to start. Battery stays low.

I drive 30 minutes to work battery doesn’t change at all.

Here is what I know to check based on experience and haynes manual:
Battery connection
Mounting bolts for alternator

And thats all i really know to check.

Now, I wonder if the HVAC system is pulling extra, because my coolant temp was reading kinda low, turned on the heat and it went up some. But the battery didn’t drop, but my fans fent minda weak and heat was never really there. Could I have a short in this system? Would that cause it or is that a separate issue?

EDIT: I started my truck, voltage held. Just not charging. Using my power windows drains on it a little but it seems to bounce back from it. Could my battery have a bad cell or the like and thus it won’t charge to where it used to?

Go have your battery and alternator tested.


Batteries don’t last forever. You don’t want to be stuck in the middle of nowhere with a dead battery.A towing is a lot more expensive than a car battery.

Welp I had autozone test and charge the battery. Thats good, the voltage regulator failed though.


Does anyone know what alternators was used in my pickup? Or anyone have a website they go to in order to look up their alternator?

The internet is your friend or you could just get it at the Autozone that did the free testing for you.

I can get the regulator there its just that in order to determine which regulator I have I need to pull it off and have them test it. Or I just need to find out what my alternator rated amps is and then I order it based off of that. just enter the year, make and model of your pick-up

Definitely a better price for sure.
I have 3 options. All things considered im pretty sure its a 95 amp given I have the upper level trim and what else I have going.

Is the regulator part of the alternator, or is it a separate part placed near the firewall or on top of a fender well? I ask b/c the alternator on my own Ford truck is a separate from the alternator, located on the firewall, but on my other vehicles it has always been part of the alternator ass’y.

Im honestly not sure. This is the first non-self caused electrical issue I have had. (The last one I had was when i replaced my steering column and forgot to attach a wire).

I had a site suggested to me and I will try it tomorrow when i get in my truck and get my vin written down. Ill let y’all know how it goes.

1 Like

Well, I entered my VIN and it pulled up the proper part per engine size. Looks like I need a 95 amp regulator.

Evening all. Charging system finally took a crap on me. Left work and the volts started dropping. Jumped it twice to get home. Well, more or less charged the battery back up. Never died I just pulled over and had the wife’s car charge it up.

So, I replaced the voltage regulator… jumped the truck… unhooked the cables and battery voltage started dropping again. I replaced the regulator with a 95/130 amp one. (Which is the correct one, which should just be the back plate section with the “test ground here” thingy marked on the back)
So next step replace the alternator with a new one? If not that then battery? Any reason that replacing that might fail for any other reason?
BTW: my alternator has 3 bolts… unless the mystical 4th bolt is a small one in the back that isn’t used for mounting.

If I had the problem, and the alternator belt, pulley, and tension look good, I’d take it to a shop for a charging system and battery load test. Shops have a special machine that does that job in a jiffy. Some parts stores offer that service too. With that test report you’ll know what parts need to be replaced.

Edit … hmmm … I notice above you took it to AZ for that test, and that’s how you decided to replace the voltage regulator. I got to wondering why you replaced the regulator b/c that’s not the usual problem part for this symptom. It’s usually the alternator or the battery or fuses/wiring/grounds. I had that symptom happen on my Corolla one time and it turned out to be a soldered splice in the wiring harness that was bad and came undone. Maybe instead of a parts store, take it to an inde shop for that test. You can still decide to replace what’s broken yourself if you like. I’m guessing you’ll be replacing the alternator. Good advice below by Nevada, make sure the battery is fully charged before hooking up your new alternator.

The alternator may have failed, how did they prove that the voltage regulator failed? Did they ground the alternator field to test the alternator output? I don’t think a counter person at Autozone will do that, I think they were guessing.

Recharge the battery with a battery charger before starting the truck with the new alternator, the heavy draw from a discharged battery can damage a new alternator.

1 Like

Hmmm I will have to search around to see what’s available to me to have it tested.
Regulator is attached to the back of the alternator.
Now, if I had a wiring issue, wouldn’t that blow a fuse?

A short circuit would blow a fuse, but an open wouldn’t.