Alternator issues 2nd Gen

[Macland]

So I had a bad battery today, replaced under warranty thank you duralast gold top, and the issue that concerns me isn't that the battery crapped out but that supposedly my alternator is over charging the battery and essentially cooking it. This is all according to the guy at az with the handy dandy little testing tool.

Has anyone had this happen? And they quoted me at $154 plus tax to replace it.

 

[Macland]

I also only have about 60k on the odometer so that's odd as well.

 

[Muadeeb]

Fire it up, rev the engine to about 2k, and put a volt meter on it. Should be about 13.8v

 

[granitex]

Don't take the "expert" evaluation of the minimum wage AZ parts monkey at face value. The last one that i talked to said that he had a hard brake line at just under 4 ft, 52 inches to be exact. Had to use a pen and paper to show him that 4 ft is 48 inches.

 

[obi_krash]

Don't take the "expert" evaluation of the minimum wage AZ parts monkey at face value. The last one that i talked to said that he had a hard brake line at just under 4 ft, 52 inches to be exact. Had to use a pen and paper to show him that 4 ft is 48 inches.

Must have been using their super special duralast HD ruler.

But Mac, I actually have heard of that happening. My ex-wife's mitsu eclipse had that issue. When it essentially chewed up the 2nd battery we figured something was up. This was back before I was back to wrenching again so her dad had it looked at while I was at work. Never did explain why it happened, just replaced it and never dealt with it again.

So it's possible, I don't understand or know why, but it's not some one off thing happening.

 

[Macland]

Thanks guys,

That was my first instinct too, not to trust the guy. I told him I'd give it a few days, especially after the guy complained about his new tool saying it was so hard to get a good connection.

Well my plan is to have the alternator checked Friday and go from there. I'll definitely be price checking alternators rather than just taking their quick offer.

 

[metzican]

Mac if you have a volts meter, Put it on the alternator rev up the engine to 2k as described and turn on the head lights. Your battery should read around 12.4-12.8 volts. and when the alternator kicks on it should read 13.6-14volts.

 

[J Everett]

If you are going to replace your alternator, go Mean Green. They're pricey, but worth it if you have a winch and extra lights, etc.

 

[chrishaynesusa]

X2 on mean green

 

[metzican]

Still need to get my green mean

If you have lots of accessories that you like to run go with the above.

 

[metzican]

So similar to this. I installed my mean green and it outputs 13.7-13.9 volts all the time. With the OEM alternator it seemed like it would turn on and off. Not the alternator but the charging to the batteries. Is this constant charge to the battery bad? or is 13.7-13.9 volts all the time fine. I'm about to go on a 4 month 25k mile road trip and don't want to keep frying all 4 batteries.

Is it normal for the voltage to be high constantly with the vehicle running? or is the alternator essentially suppose to turn on and off as needed?

 

[mudchet]

I have my Ultragauge device plugged into my odbII port all the time. I have a factory alternator and I normally see voltages you mention. I dont see it fluctuating, its steady. Does that help?

 

[metzican]

Yes that does help. For some reason I kept thinking m voltage would go up and down on my bully dog with my old Alt...

 

[TJTJ]

The volts will be pretty consistent w/in those limits...but the AMPS will vary with load.

For example, if idling with all electrical stuff off, and you suddenly lower the windows, hit the brights and roof lights, turn the AC to max, blare the radio while hitting the brakes, etc...the alternator belt might even give a squeak/squeal of protest as the resistance to the pulley goes up with the increased amp draw.

You'd need an amp meter instead of a volt meter to see the difference of course.

 

[mudchet]

The volts will be pretty consistent w/in those limits...but the AMPS will vary with load.

For example, if idling with all electrical stuff off, and you suddenly lower the windows, hit the brights and roof lights, turn the AC to max, blare the radio while hitting the brakes, etc...the alternator belt might even give a squeak/squeal of protest as the resistance to the pulley goes up with the increased amp draw.

You'd need an amp meter instead of a volt meter to see the difference of course.

TJTJ are you able to explain how the amperage is controlled / regulated? Just curious.

 

[metzican]

The volts will be pretty consistent w/in those limits...but the AMPS will vary with load.

For example, if idling with all electrical stuff off, and you suddenly lower the windows, hit the brights and roof lights, turn the AC to max, blare the radio while hitting the brakes, etc...the alternator belt might even give a squeak/squeal of protest as the resistance to the pulley goes up with the increased amp draw.

You'd need an amp meter instead of a volt meter to see the difference of course.

I know there is a voltage regulator so when it is "on" it will give a steady voltage. I also know the amps will vary via RPM. I just did not know if we had a solid state solenoid in line to turn on and off the Alternator to prevent from overcharging.

 

[TJTJ]

TJTJ are you able to explain how the amperage is controlled / regulated? Just curious.

I know there is a voltage regulator so when it is "on" it will give a steady voltage. I also know the amps will vary via RPM. I just did not know if we had a solid state solenoid in line to turn on and off the Alternator to prevent from overcharging.

Correct, just add that, as the voltage is trying to be kept constant, the voltage regulator is increasing the amps to maintain that voltage when the demand goes up. The output is controlled by the rectifiers in that part...and if the rectifiers are recti-fried, well, the current is not regulated anymore, or, at least, not as well as it needs to be, etc.

Depending upon which diodes get fried/damaged, etc...you can sometimes even maintain voltage, but amps are uncontrolled, etc....which can mean too low an amp or too high an amp supply, etc.

I find that this is the main limitation on rebuilt alternators, at least for me...as the PepBoys, etc, techs have told me a used alternator was fine, but, the rectifier diodes were shot, and it wasn't fine at all...it was a paper weight, etc.

So the load, if low enough, say on an Autozombie test bench, might be within the remaining voltage/amp capacity...so they call it a good alternator. If the loads are increased, as its typically a stepped test when done the "real way", you can better see if a diode is burned out, etc.

I found a local alternator/generator shop, and THEY can do real tests that are more definitive, and, I skip the big box moppets and go there with a questionable alternator find instead.

 

[Intender]

Everything in your truck should be capable of working at up to 14v. Most alternators are designed to put out 13.5v to 13.7v. But due to variable speed that its being driven at and loads put onityou may see anything from 11.7 up to 14.2. Anything less outside that range usually points to a bad alternator or voltage regulator. Alot of inverter manufacturers and stereo amplifier manufacturers take advantage of this and bench test their devices at 14v to give you a rating for amps or watts for the device. For example i had an old ppi amp on my cars for years. They bench tested every amp before they shipped it out and put a paper with the watt ratings in the box with it. My amp was an a600.2 it was rated at 100 watts rms in two channels @ 4 ohms. 600 watts mono rms @ 2 ohms. Both at 14v. Mine put out around 140x2 @ 4 ohms and almost 800x1 @ 2ohms. I ran it at 1 ohm and had it bench tested at almost 1100 watts @ 12.7v which is what my car put out and over 1200 @ 14v.