Blitzkrieg3002

So the other day I was driving to work and noticed my Charge and Brake light come on at the same time. They come on Intermittently from anywhere from 1 to 15 seconds they will stay on. While they are on the Charge Voltage gauge jumps from charging from aroun ~13v up to 18 and my heater fan and windshield wipers speed up, and headlights and dash lights get brighter during when they are staying on.

Seems logical that it would be the altinator starting to go out. Well the internal voltage regulator that's built into the alternator is my guess. But i'm thinking of replacing the alternator. The only thing is i've heard some people say a bad battery can cause overcharging as well.

I'm just wondering, has anyone come across something like this before? or has anyone heard of something similair to this? I'm thinking i could have autozone test the altenator, but it sometimes doesn't happen until 15-20 minutes driving. and it doesn't happen too frequently but for the past few days it's happened every time i've drove the car spaced out about 10 - 15 minutes each time the lights come on and charging increases.

any input would be great. Thanks Yotatech users.

RAD4Runner

I've experienced that, too, and I have a new alt. 13V to 17V.
I thoroughly cleaned battery contacts and am monitoring. I also noticed that my battery post rotate when I check tightness of terminal around post.
So yes, possible that bad internal circuit of battery or poor connection could cause it.

Theoretically:
You lose contact and stator gets low excitation current (IG terminal), alt generates low voltage (13V). Regulator sees low voltage so attempts to increase it by sending more IG current. At the same time, because of vibration, things make better contact, causing too much excitation current, hence, overvoltage (18V). repeat.

OR, internally, battery opens or presents high resistance, meaning less load to alt, this would instantaneously cause V to spike (18V), regulator atteomts to lower voltage, then battery shakes, makes better contact internally, loading the alt and causing too low a voltage (13 or less).

At the same time above are happening circuit sees under/over voltages and brings "L" output low. This provides low V to charge and brake error lights. These occurrences are momentary so error lights flicker.

No wonder... Isn't that illegal? J/K - LOL!

Blitzkrieg3002

Interesting, Thnks for the re RAD. that certainly explains how a battery can cause this problem. I'm thinking, to troubleshoot the problem could I start the truck, then while the truck is running, disconnect the battery terminals and let it Run off the altenator and drive it around for a bit to see if it happens then. if not, then probably most likely a battery?

It's a farly old battery, same one since I bought the truck used ~40,000 miles ago, same with the altenator for that matter tho too. but the battery just looks like it's got some age.

I've had problems with loose grounds in the past, but i've checked those this time and everthing seems snug on the terminals.

RAD4Runner

Make sure you thoroughly clean connections>? I've had issues with that although connections seemed clean. (https://www.yotatech.com/forums/f199.../#post51939319)

Not sure if safe to run without the battery, altho if it's an older truck with simple electronics it should be OK. I would let others with experience doing that chime in.

How about to be safe, find comparable battery and try running on that? That reminds me to do it myself. Maybe I should switch my Corolla's with my Runner battery and see.

Co_94_PU

iTrader: (-1)

A properly functioning regulator will update faster than you can blink, if your getting voltage spikes long enough to notice it's probably damaged.

That said, of course I don't know which parts are used in the regulator off hand but you can make a safe bet it's got switching times in the millisecond range.

And of course the obligitory.. The books say "Do not disconnect the battery while the engine is running."

Some post type batterys are just screw type batteries with posts screwed into them.

RAD4Runner

hmmm... good to know. Will check if I can tighten the post, then