Fried Alternator ???

2. The other thing is the battery was very week, like 9.5 volts week and i did not let it charge before test driving it. About 5 minutes into the test drive I cranked the stereo up and probably was straining the alternator a good bit.

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This is what murdered your alternator!!!!!

Even low batteries (11-12v) you should fully charge before installing.

The alternator was loaded down completely trying to charge a VERY dead battery. Then, you "cranked the stereo".....

Also, the word you're looking for is "weak", not "week"

The other thing that was strange during the test drive when alt failed, the van completely died 100% instantly due to the short. Shouldn't the main 120 amp fuse have blown first? i put a DMM on the battery and discovered the direct short. i guess the battery was too weak to blow the fuse, the wires weren't hot ether, very strange.

Just thinking out loud weather this was my fault or a bad alternator.

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The van "completely died" because your battery was SO DEAD it couldn't run the vehicle's basic electrical system.

This was completely user error, not a faulty part.

Fully charge your battery with a battery charger SLOWLY

and then have it load tested. I'm guessing it is so low because you just kept driving the car when the alternator died the first time. My guess is the battery is toast too, unless it's less than a year old.

Also, the word you're looking for is "whether", not "weather".

That's just my inner asshole/grammar nazi talking

Yummy... Deep fried alts

I murdered it alright //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I also been known to murder the English language!
But I'm not sure why the Alt shorted. I thought as you did at first but...

Here the thing.

1. It shorted 15 minutes into the drive not right away. The battery already had 10 minutes of charge on it before the stereo was cranked so at that point the battery should have been drawing much less amps as at first start up. Also the stereo was cranked for 5 minutes before failure you'd think it would have failed right away when cranked.

2. The voltage never dropped below 14.1 every time i looked (according to my 80PRS)

3. My system is every efficient, and it probably wasn't drawing any more than 40 amps (it has a 60 amp fuse in-line.) and the van shouldn't have been pulling any more than 15-20 amps.(window down no lights on)

4 . It's a 130 amp alternator cursing at 2500 RPM(which should be peak output.)

5. It has a factory a 120 amp fuse from the Alternator.

So i'm assuming it was pulling 70-80 amps at the very max,,, (unless something else was shorting like a power door or... but then you'd think the voltage would be lower.

Thanks on the grammar, really i can't spell chit without speel check.

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not in a rude way, but do you have any sort of question or concern about this?

i have heard its a good idea to let a new alternator heat cycle so the brushes seat properly (i.e. expand and contract) before you load it up so that could be another reason why it failed.

you should be able to replace the components broken internally (voltage regulator or bridge rectifier) for relatively cheap if its a common alternator with serviceable parts

[quote name='Roland']No not really, just thinking out loud,,, and practicing my English.

I never heard of the heat cycle, good to know i'm going to look into that.
I never had a alternator short before I do was wonder what exactly fails to cause a alternator to short. All the alt's i've replaced just had low or no output, the short is just new to me and caught me off guard.[/QUOTE]

my general assumption is that the bridge rectifier is what shorts due to a fried diode. but for it to fail so catastrophically is just weird.

im not entirely sure its your fault that it failed, but if that battery is REALLY bad @adulbrich is right and that is probably why it failed on you.

no worries on thinking out loud, i do the same. just wanted to make sure we werent missing anything

try warrantying the alternator and go easy on the new one. its possible you got a bad one, but its hard to know for sure..

I murdered it alright //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I also been known to murder the English language!
But I'm not sure why the Alt shorted. I thought as you did at first but...

Here the thing.

1. It shorted 15 minutes into the drive not right away. The battery already had 10 minutes of charge on it before the stereo was cranked so at that point the battery should have been drawing much less amps as at first start up. Also the stereo was cranked for 5 minutes before failure you'd think it would have failed right away when cranked.

2. The voltage never dropped below 14.1 every time i looked (according to my 80PRS)

3. My system is every efficient, and it probably wasn't drawing any more than 40 amps (it has a 60 amp fuse in-line.) and the van shouldn't have been pulling any more than 15-20 amps.(window down no lights on)

4 . It's a 130 amp alternator cursing at 2500 RPM(which should be peak output.)

5. It has a factory a 120 amp fuse from the Alternator.

So i'm assuming it was pulling 70-80 amps at the very max,,, (unless something else was shorting like a power door or... but then you'd think the voltage would be lower.

Thanks on the grammar, really i can't spell chit without speel check.

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I don't know what shorted internally without looking at it torn apart.

1. It would have shorted right way if it was not rebuilt properly and had something internally shorted to begin with. Driving for 15 minutes tells me that components in the alternator had time to heat up. It simply wan't able to dissipate the heat as quickly as it built up. My guess is a solder joint melted and shorted to the case. My US 390 amp alternator has silver solder instead of regular lead solder to give it a bit more amperage capacity before failure. 10 minutes of charge was basically nothing. If a battery came into our shop at 9.5v when I worked there, we would quick hit it with a 250 amp boost. If it was taking a charge, we would put it on a 10-15 amp slow charge overnight or even longer. 10 minutes was not a significant amount of time for an alternator to charge a battery, hence why the car immediately died when the alternator shorted. The battery didn't take enough charge to support the vehicle.

2. Because the alt "sensed" such a low voltage, it kept compensating and trying to maintain a higher voltage charge.

3. Knowing this about your system, I doubt it was significant in the failure of your alternator. The very dead battery is the culprit.

4. Stock alternators are not meant to charge a dead battery. Their sole purpose is to maintain the starting battery's charge and run stock electrical accessories. Car audio alternators are a bit different, and most legitimate manufacturers use higher quality parts meant to be loaded down more and withstand the abuse. A stock alternator does not like to put out its max amperage for very long. That's why when people put a system in their car that is too big for their alternator to keep up with, it eventually fails. The difference being that they have a healthy battery to buffer the abuse.

5. The "130 amp" alternator most likely put out a bit less than 130 amps. Also, the fuse was designed to pass 120 amps. An extra 10 amps wouldn't instantly blow it. A fuse blows when the amperage flowing through it heats up the metal enough to break the circuit. Without further information, I don't know if it was a "slow blow" or "quick blow" fuse. If the alt was putting out 120-125 amps max, that wouldn't necessarily pop the fuse.

Yes, if something else was shorting, your voltage would continue to go down.

The battery was just enough to barely start it one time, but yeah i get now why I should have charge it up first.

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I am very surprised a battery at 9.5v was able to start a car..

I just wanted to make sure the alternator could do the job, so charging it before hand seemed counter my goal.

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Charging the battery is not the alternator's job. Maintaining the battery and supplying enough power for accessories is its job. You need to grasp this concept.

That van had the OEM alternator for at least 200K miles on there before and it took similar abuse but never failed, well,,, actually it did fail Hum.

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The OEM alternator failed under normal conditions of wear and tear, plus a small sound system adding an extra load. When it died, you continued to drive the vehicle, torturing the battery. The rebuilt alternator failed because it was abused.

Anyway, next time, i'll charge battery first, and i think OEM or high performance may be worth the extra coin when it comes to alternators.

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Yes, charge the battery the next time something like this happens. It's your money, spend it on OEM or high performance alternators if you want.

I desulfurized the battery with a little pulse charger over night load tested it and now it's good to go //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

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You *desulfated* it.

"Pulse charger" //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

What shop load tested it? Did they use an analog carbon-pile with a knob and gauges or a small digital device that prints off a nice little report?

That van has 320 k on it it turns over fairly easily but still runs like a champ.
We can disagree on the job of the Alternator. In theory i'd agree it's not for charging the battery,,, but in reality it's often called on to do just that. Anytime you have jump start a car, because someone left the lights, on or ran there stereo with the car off for to long. Or even when a car has a weak battery, the alt is required to do that extra duty. And alternators do it without issue every day.

Sulfate is what accumulates on the plates of your battery, it limits the charge your plate can accept. High voltage 15.5-16 can help desulfate the plates but some chargers send too much amps and risk boil off... A low amp high voltage pulse charger can rejuvenate a weak battery be knocking the sulfate off and back into electrolyte solution... I have a roll around 250 amp charger also, but the pulse charger does a better job just take longer. The best way to use the pulse charger is to charge the battery, then discharge the battery, and repeat a couple of times if needed.

I just realized iv'e had the same analog load tester for 40 years. It looks very simular to this one.

https://www.walmart.com/ip/Schumacher-100-Amp-Capacity-Economy-Battery-Load-Tester/21642133?wmlspartner=wlpa&adid=22222222227016799366&wl0=&wl1=g&wl2=c&wl3=40839783632&wl4=pla-78653487152&wl5=9010806&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=21642133&wl13=&veh=sem

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I'm done....