Is my alternator bad?
10-16-2005, 04:09 AM
#1
Is my alternator bad? Hey guys, could use some advice.
I've noticed that my car drops volts after it has been running a while. It will sometimes go down to the quarter line mark. I heard the voltage gauge is not always accurate so i did some logging with datamaster and it showed the voltage occasionally dropping into the 11s. Isn't that way too low?
It is definitely not the battery because this battery is less than two months old. I replaced it because my old battery was completely dead (which itself wasn't that old). I'm thinking maybe I have a bad alt that is killing the batteries. Is there anything else I should check that would cause it to drop volts?
I've noticed that my car drops volts after it has been running a while. It will sometimes go down to the quarter line mark. I heard the voltage gauge is not always accurate so i did some logging with datamaster and it showed the voltage occasionally dropping into the 11s. Isn't that way too low?
It is definitely not the battery because this battery is less than two months old. I replaced it because my old battery was completely dead (which itself wasn't that old). I'm thinking maybe I have a bad alt that is killing the batteries. Is there anything else I should check that would cause it to drop volts?
10-16-2005, 10:24 AM
#2
use a multimeter to check the output voltage. you also just bite the bullet and pull your alternator and rebuild it. very easy and extremely cheap as long as your rectifier is still good. brush assembly is 5-10 bucks and if you need a voltage regulator they are like 40. i rebuilt mine earlier this year. you can also go to autozone. usually they have free alternator and starter tests.
10-16-2005, 12:16 PM
#3
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Mine does the same thing, I have had 4 alternators in the car now. I have a 1200 watt system in the car, so thats likely the cause of the alternators goin. Is there a high output alternator out there that will bolt in the stock position?
10-16-2005, 02:08 PM
#6
i had to order them from o'reilys. the brushes were in stock in the warehouse and i needed a voltage regulator, main reason for the rebuild, which the guy ordered for me. that took 2 days i think. when i called autozone about the parts they were like "brushes? you mean to clean it?". dealerships also carry the brushes but not the regulator.
10-19-2005, 12:05 AM
#7
Staging Lane
sounds like an alternator problem. I eat them up in my car as well (00 Z28 with a 1200 watt stereo too) whatever you do, do not get a Mralternator.com alternator. I ordered their 200amp one, and within 1 week the bearing ate itself up and I had to replace it!
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10-19-2005, 11:02 AM
#8
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I think it's an overtemp problem in the regulator.
Mine did that from day one, off the truck. But once
I set the fans lower it hardly ever does it. Idle and
high load require the most field current and put the
most internal heat to the regulator inside the case.
I guess upping my idle to 700RPM also helped that.
Mine did that from day one, off the truck. But once
I set the fans lower it hardly ever does it. Idle and
high load require the most field current and put the
most internal heat to the regulator inside the case.
I guess upping my idle to 700RPM also helped that.
10-20-2005, 09:14 PM
#9
Ok now I have another strange issue.
I put in a new alternator and then did some testing. Reading across the battery with a voltmeter I get between 13.9-14.2 so that looks better, but with datamaster (and the dash gauge) i am still only getting between 11.9-12.2. So it seems the pcm is reading a different voltage. Anyone know what location it is reading this from?
I put in a new alternator and then did some testing. Reading across the battery with a voltmeter I get between 13.9-14.2 so that looks better, but with datamaster (and the dash gauge) i am still only getting between 11.9-12.2. So it seems the pcm is reading a different voltage. Anyone know what location it is reading this from?
10-22-2005, 11:52 PM
#10
Originally Posted by jimmyblue
I think it's an overtemp problem in the regulator.
Mine did that from day one, off the truck. But once
I set the fans lower it hardly ever does it. Idle and
high load require the most field current and put the
most internal heat to the regulator inside the case.
I guess upping my idle to 700RPM also helped that.
Mine did that from day one, off the truck. But once
I set the fans lower it hardly ever does it. Idle and
high load require the most field current and put the
most internal heat to the regulator inside the case.
I guess upping my idle to 700RPM also helped that.
Thanks.. i dont want to pay $80/hr to have someone try to locate the cause or our electrical issue.
Also can someone tell me, does the alternator have to be taken out of the car to be tested?
10-23-2005, 02:06 PM
#11
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Originally Posted by infinitebird
Ok now I have another strange issue.
I put in a new alternator and then did some testing. Reading across the battery with a voltmeter I get between 13.9-14.2 so that looks better, but with datamaster (and the dash gauge) i am still only getting between 11.9-12.2. So it seems the pcm is reading a different voltage.
I put in a new alternator and then did some testing. Reading across the battery with a voltmeter I get between 13.9-14.2 so that looks better, but with datamaster (and the dash gauge) i am still only getting between 11.9-12.2. So it seems the pcm is reading a different voltage.
