alternator fried

[RSG]

i replaced my alternator last April. The new one seemed great, high voltage output at idle (>14.2V), shiny and new. Then it started to dip in voltage output about 2-3 weeks ago, and yesterday it stopped charging altogether and the idiot battery light went on. I took it to an alternator repair shop and he said it is fried...and it does appear to have gotten pretty warm based on the color of the windings...I recall the frame was pretty warm too the few times I checked.

Batteries are less than a year old and I check each cell, all a-ok and fully charged up each night while this problem was developing. The only other thing I can think that would fry the alternator is a continued (large) load like a set of glow plugs that won't shut off or something? Is it worth testing the glow plugs for this, or just get a warranty replacement (I hope) and try again?

 

[DaveBen]

Something killed it. The Glow Plugs draw the most current while running (if they are still on). Check the Glow Plug circuit (relays) to make sure they are shutting off after your truck starts. They will remain on for a minute or two after starting.

Dave

 

[RSG]

Yeah...good idea. I had relied on watching the volt reading on my Aux Idle Controller -- that's how I knew it was not charging, and you can surely see when the GP relay opens back up. But since the readings are around 12.4-12.8V, after a few minutes, I'm guessing the GPs are shutting off, at least NOW.

 

[Dieselpwrdredneck]

Were did you get the alternator? new or reman? could've just been a bad alernator if ya cant find anything wrong. Had it happen to me a few times

 

[RSG]

National Quick Start Sales...Michigan. It was new. It put out 14.5+V when installed...I'm thinking its internal regulator might have been a problem from the start. Waiting on them to honor their warranty, we'll see...

 

[Dieselpwrdredneck]

hope they come through for ya

 

[BIG JOE]

Just an Opinion Guyz & Galz, but the stock Alts on these PSD's are Marginal at best. They put out the Volts, but Not Enough Amps.. during, or after, the loads these things create during Starts and such.. Long Term.

If you've upgraded the Batt CCA's.. forget the stock alt Service Life.. altogether.

I upgraded my Batts and went to a 160 amp "Large Body" Alternator, and never looked back.

Joe

 

[RSG]

...I upgraded to a large frame 160A too...last April. I didn't look back until it went south over the past few weeks!

I sent it back to the company 8d ago, and nobody answered a phone call all last week. "Please call back"...not even a way to leave a message. So it will be interesting to see if they are going to come through or not.

I had called them as it was failing and they didn't give me much info other than if, when they tested it, if it put out more than 13.5V they considered it ok...didn't say if it was under load, open circuit, or whatever. It was charging at lower voltages the last few weeks, then only intermittently, then it just went TU. My batteries are all ok according to their specific gravity. The glow plugs turn off after a spell according to my voltage reading. So I think it was a bad alternator.

The thing that has me wondering is why this alternator put out such a high voltage -- around 14.3-14.6 V -- or whether that is 'normal'...Joe do you know what your max charge voltage is, say after a start on a cold morning and after the GPs shut off?

 

[BIG JOE]

RSG,

My 160 amp Alt puts out 14-14.5v after start loads, then 13.5-14v after that..at idle. [So far].. my National Quick Start Alt is doing well

Your Batts may be right on with thier specific gravity.. but have you load tested them lately ??

Here's a site with all you'd ever want to know about 12v stuff. Maybe TMI about 12v stuff ?

www.marxrv.com

Joe

 

[RSG]

Thanks Joe. I liked this bit on "Testing your batteries":

"Use one of the following methods;

1. Allow the battery to sit for six hours with no load or charger connected, or...
2. Apply a 25 amp load for three minutes and wait five minutes, or...
3. With a battery load tester, apply a 150 amp load for 10-15 seconds.
...
Check both the specific gravity in each cell with a external hydrometer AND the battery terminal voltage with a digital voltmeter without the engine or converter/charger running. If the state-of-charge is BELOW 75% using either the specific gravity or voltage test then the battery needs to be recharged BEFORE proceeding.
Replace the battery, if one or more of the following conditions occur:

If there is a .050 or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell(s),
If the battery will not recharge to a 75% or more state-of-charge level.
If digital voltmeter connected to the battery terminals indicates 0 volts, you have an open cell, or if the digital voltmeter indicates 10.45 to 10.65 volts (5.2 to 5.35 volts for a 6 volt battery), you have a shorted cell. [A shorted cell is caused by plates touching, sediment build-up or "treeing" between plates."

I have had my batteries dead once since new 12 months ago. I regularly float charge and desulfate them. I didn't load test 'em but do recall at least one cell was low on SG -- so I'll go back and check 'em again. They were pretty cheap, and iirc they had a 6 month warranty; maybe they are the culprit for my fried alternator, but that would be a first. When they get hit with a load, such as the GPs, until the alternator started acting flaky, they sat at 12.6 or so (hooked up) after the load was taken off...so I've been feeling pretty lucky with them...

Meanwhile, those folks at National Quick Start...are beginning to make me think they either have serious office problem...or else, they're shysters. They don't answer their phones, I've left 3 messages and one email over the last 8d. I'm using the number on their website and another number on a card they provided with the alternator. Irritating...to say the least.