How to know if alternator is charging?
08-16-2004, 06:38 AM
#1
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How to know if alternator is charging?
I *think* that the alternator in my 1988 5000CSTQ isn't charging. Last week I replaced its voltage regulator / brush assembly. While driving it this week, is there a way, short of having the battery discharge to the point at which it won't start the car, to determine if the alternator is charging or not?
PS: I don't own a clamp-on DC ammeter.
PS: I don't own a clamp-on DC ammeter.
08-16-2004, 07:18 AM
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drive over to autozone if you can. they can test. if not ...
when my alternator when .. the voltage on my battery dropped. the car was draining batteries. so when i had to drive it i'd have one battery running and one in the trunk just to get me home.
08-16-2004, 10:29 AM
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When mine went two weeks ago
It lit the battery and ABS idiot lights immediately. After that the volt meter showed 12 volts and of course, dropped a bit the longer I drove.
Mine had fried one of the diodes.
Been thinking about that to try to understand. I would imagine that there are 4 diodes for a bridge rectifier. I would also think that one side of the bridge could be bad and the last half would still allow charging, just not as much, until the last bridge goes and then nothing. Think that is what happened to mine.
Mine had fried one of the diodes.
Been thinking about that to try to understand. I would imagine that there are 4 diodes for a bridge rectifier. I would also think that one side of the bridge could be bad and the last half would still allow charging, just not as much, until the last bridge goes and then nothing. Think that is what happened to mine.
08-16-2004, 11:26 AM
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I think that most car alternators are three phase (thanks, Nikola Tesla)
I think that each phase (of three phases total) is rectified with a full-wave rectifier (3 phases x 2 diodes per phase = 6 diodes total).
Advantages of three-phase over single-phase design in this application include less ripple in DC output and less iron needed (translation: lower cost and weight) to support the magnetic field that's needed for a given output current.
Advantages of three-phase over single-phase design in this application include less ripple in DC output and less iron needed (translation: lower cost and weight) to support the magnetic field that's needed for a given output current.
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08-16-2004, 12:15 PM
#8
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push and hold "outside temp" button and press "off", choose channel using "warmer", to read
the value of the particular channel press colder button. To get back from troubleshooting to normal mode press auto or any other button
HTH
Sergei Pokrovsky
'87 5KCSTQW, 187k miles
Anchorage, Alaska
HTH
Sergei Pokrovsky
'87 5KCSTQW, 187k miles
Anchorage, Alaska
08-16-2004, 01:13 PM
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Check with a voltmeter on the battery, should go up when you start the car.
To about 13.5 volts or so. If not alternater is bad. Also if it's any less than 13.5 your battery will probly not charge.
My .2 cents of info.
My .2 cents of info.
08-16-2004, 03:32 PM
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OK, so they only pull the positive portion of the wave
three times per revolution. I guess.
Another note. Since my alternator was replaced the car has been performing a lot better than it has since I got it. Mileage is also noticibly better.
I don't think that it is due to the charging but rather to the old one having bad bearings.
Since I had the car I have heard a rattle sort of sound when idling at times. I don't hear that any more. My guess is that bearing noise was interpretated as pre-ignition by the knock sensor and the timing was always limited from what it was supposed to be.
How's that for a SWAG? : )
Another note. Since my alternator was replaced the car has been performing a lot better than it has since I got it. Mileage is also noticibly better.
I don't think that it is due to the charging but rather to the old one having bad bearings.
Since I had the car I have heard a rattle sort of sound when idling at times. I don't hear that any more. My guess is that bearing noise was interpretated as pre-ignition by the knock sensor and the timing was always limited from what it was supposed to be.
How's that for a SWAG? : )