Alternator / Battery Troubleshooting

[MNgopher]

I've got an issue I want to make sure I am diagnosing correctly - it's currently -13F outside (real temp, not windchill), so I want to be right the first time!

Issue: '99 F150 with the 4.6l V8 and Heavy Duty Alternator (130 Amp). Dashboard went crazy while driving to work, cycling on an off. The battery idiot light illuminated, and when the guages appeared to work, the voltage was clearly too high.

I limped the truck home (less than a mile). Popped the hood, and the battery clearly vented some acid. After neautralizing the acid and rinsing, checked the battery voltage and it was 10.5 volts, truck not running. A quick jump, and a recheck of voltage at the battery was nearly 20 volts. Needless to say, the truck was shut off!

So, my diagnosis is an overcharging alternator with a failed voltage regulator. Likely fried the battery too. Guessing I need to replace both

Only 1.5 years and 25,000 miles on both - the stock setup got me 150,000 miles...

Am I missing something? Other suggestions? I only want to deal with this once given the weather I get to work in, outside on the driveway!

 

[ChiTDI]

Sounds right to me, are you replacing with the stock set up this time?

 

[MNgopher]

The alternator has a lifetime warrantly on it, and the battery has a 24 month free replacement on it. Based on that, we'll replace with the same parts... I'm guessing the alternator took out the battery, so I'm not worried about the reliability of the battery - just the replacement alternator. (The alt is a NAPA unit).

 

[kgb007stb]

That is clearly correct, the “venting of acid” as you describe is a condition that batteries experience when overcharged, the battery no longer accepts current as it is fully charged so it dissipates excess energy through breaking down electrolyte into H, and O. Usually this causes excessive gassing which stresses the plates, and the battery becomes hot to the touch, I-squared R loss in joules/second.

I’ve seen this multiple times on malfunctioning charging systems, the battery may or may not be shot, flooded batteries tend to take overcharging the best as they compensate for overcharging by the above mentioned condition. You can have it load tested or for the peace of mind replaced.

 

[NYEngineer]

Wow, I wonder if -13 is cold enough to freeze the battery and POSSIBLY the alternator was only charging a portion that was not frozen.

I would replace both. Sounds like you did it right.

 

[soldierman]

I had a honda accord overcharge once. running it was charging about 22 volts. the headlights worked really well that night. I checked it out when I got home and the next morning that battery was dead. It started fine when I got home.

 

[MNgopher]

The morning this happened it was right around 30-35F (a heat wave compared to much of the rest of the month), so I certainly hope the battery was not frozen! I don't think the battery would be frozen in those mild conditions. The battery is relatively young and had not shown any signs of venting at all before this incident.

 

[brianl703]

A frozen battery wouldn't cause the alternator to put out 20 volts.

Either the regulator is bad or the voltage sense input isn't getting any voltage. (I'm not sure how most regulators respond to the loss of voltage sense..seems to me they'd jack the voltage way up).

 

[Donald]

I would assume your alternator is bad and should be replaced. However it also shortened the life of your battery and hopefully you can get that replaced also since its the fault of the alternator.

Good luck.

 

[mechtech2]

The alternator puked, and pulled a Sampson death on the battery - they went down together.

 

[SHOZ]

 

[MNgopher]

Followup: Alternator definitely bad. No hassles on the lifetime warranty replacement at the NAPA I originally purchased the unit at.

The battery, after charging, still passed the battery test, so no free replacement on it. Looks like I'll have to keep my eye on that. I'm sure the winter will kill it quickly if its really gone terribly bad.

Weather was nice during install - 20 F, Windy, and beating the snow that was on the way. Good times...

 

[NYEngineer]

-20??? I will NEVER move to MN.

 

[Cutehumor]

how long did the napa alternator last? I got a duralast gold alternator (new not rebuilt) in my sunfire that has been running since 2001, lifetime warranty to boot.

 

[MNgopher]

NY - sorry, it was 20 above, not 20 below. I see how that post could look that way!

Cutehumor - Honestly was disappointed in the lifespan, 1 year, 8 months, 19,000 miles, with a lifetime warranty. It is the heavy duty 130 amp alternator. Hoping this isn't one of those lifetime warranties that means I'll be in there every couple of years. Part of the reason I've usually shopped NAPA - to avoid the cheap junk. Time will tell...

 

[artificialist]

Originally Posted By: MNgopher
NY - sorry, it was 20 above, not 20 below. I see how that post could look that way!

Cutehumor - Honestly was disappointed in the lifespan, 1 year, 8 months, 19,000 miles, with a lifetime warranty. It is the heavy duty 130 amp alternator. Hoping this isn't one of those lifetime warranties that means I'll be in there every couple of years. Part of the reason I've usually shopped NAPA - to avoid the cheap junk. Time will tell...

That is sad. I have known so many guys that trust no reman alternator or starter except NAPA.

That in mind, I see certain cars that frequently go through alternators (and other stuff) because the OE part is poorly built, too hot, or undersized, so there isn't much a premium rebuild can do to extend the life of it.

 

[Cutehumor]

Originally Posted By: MNgopher
NY - sorry, it was 20 above, not 20 below. I see how that post could look that way!

Cutehumor - Honestly was disappointed in the lifespan, 1 year, 8 months, 19,000 miles, with a lifetime warranty. It is the heavy duty 130 amp alternator. Hoping this isn't one of those lifetime warranties that means I'll be in there every couple of years. Part of the reason I've usually shopped NAPA - to avoid the cheap junk. Time will tell...


interesting, you mention Napa. I believe "Greaser" said he had a Napa Starter only last 3 months recently. maybe Napa has gone downhill?

 

[brianl703]

There's a local place here called Artie's Auto Electric, they rebuild starters and alternators in-house and their quality is apparently very good. Their prices aren't bad, either--they quoted me $90 to rebuild a Ford Taurus 130 amp 3G alternator. I think Autozone wants $150 for that same rebuilt unit.

Maybe it'd be worth looking around and seeing if there's a local place that rebuilds alternators and starters?

 

[Donald]

You are better off at a local rebuild shop for starters and alternators. They can tell you if you need a rebuild or just a part and they toss the really junk alternators in the scap bin and only rebuild the good ones (as in good base parts).

But of course there are many rebuild shops. But if they can stay in business with AZ and AAP around the corner, they must know their stuff.

For example a local shop told me on rebuilds they replace the entire diode bridge, but the overseas rebuilds they just solder in a new diode to any of the broken ones in the bridge.

 

[StevieC]

That's what Champion rebuilt must be doing. I went through 3 of them in a year trying to find a good one for my VW Cabriolet. They kept failing... I took one a part before I returned it, because the regulator is easily removed on this model and found that they had just soldered a resistor over another that was still there and broken in two. Last time I buy that junk!