Voltage jumps under a load???
Thread Starter
Racer
Joined: Mar 2005
Posts: 286
Likes: 1
From: AZ
Voltage jumps under a load???
Been a while since last post...How is everybody doing these days?
Here's the skinny...
Under a load, at low or high speeds, the old Juice gauge is maxxing out after driving for 10 minutes or more. Only under a load...
Battery tests good, all connections including exciter,test right on the button. All the tests are with key off, idle sitting still, and 2/3k sitting still. I haven't figured out how to do these tests at speed. I have a theory about training the trunk monkey but he hasn't been very happy when I close the hood on him....
The questions are:
What component(s) should I consider to be the usual suspects for this?
How hot should the alternator case get? This one is getting really really hot.
Also: Doesn't seem to matter what elec components are in play, outside and drivetrain temps don't seem to matter.
Problem is fairly predictable but not entirely consistent....About 20% of the time it doesn't even show up. Some days it doesn't show up at all.
Alternator is a 1-1/2 year old unit from Autozone 65 amp factory replacement.
82 CE.
Thank you in advance for any and all input.
Here's the skinny...
Under a load, at low or high speeds, the old Juice gauge is maxxing out after driving for 10 minutes or more. Only under a load...
Battery tests good, all connections including exciter,test right on the button. All the tests are with key off, idle sitting still, and 2/3k sitting still. I haven't figured out how to do these tests at speed. I have a theory about training the trunk monkey but he hasn't been very happy when I close the hood on him....
The questions are:
What component(s) should I consider to be the usual suspects for this?
How hot should the alternator case get? This one is getting really really hot.
Also: Doesn't seem to matter what elec components are in play, outside and drivetrain temps don't seem to matter.
Problem is fairly predictable but not entirely consistent....About 20% of the time it doesn't even show up. Some days it doesn't show up at all.
Alternator is a 1-1/2 year old unit from Autozone 65 amp factory replacement.
82 CE.
Thank you in advance for any and all input.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
You can connect a multi meter to the battery posts and go for a drive, watching the system voltage. If the alternator is over charging your meter will show a high voltage while running, and this will eventually kill your battery if that's the case.
You can test the alternator under load sitting still though. Connect the multi meter to it, turn on everything from the headlights to the blower fan, and radio. Then, throttle it up above 2500 RPM and see what the voltage is.
You can test the alternator under load sitting still though. Connect the multi meter to it, turn on everything from the headlights to the blower fan, and radio. Then, throttle it up above 2500 RPM and see what the voltage is.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Your term "juice gauge" refers to a voltmeter [not an ammeter], I am assuming. You need to measure voltage with a decent voltmeter to see what the output really is. Normal charging would be around 13.5 volts. If it is higher than that after running at speed for a few minutes, the voltage regulator (built into the alternator) is not doing its job. Replace the alternator or rebuild it with a new regulator.
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
"Alternator is a 1-1/2 year old unit from Autozone 65 amp factory replacement. "
That would be the first thing I suspect, take the alternator off and have it checked.
it is easy to do, and even Auto Zone can't screw up the alternator test.
Do not tell them it is their alternator, untill after they test it.
That would be the first thing I suspect, take the alternator off and have it checked.
it is easy to do, and even Auto Zone can't screw up the alternator test.
Do not tell them it is their alternator, untill after they test it.
Advanced
Joined: Dec 2005
Posts: 62
Likes: 0
From: Brownsboro Texas
I also have a 82 CE and it has an alternator from AutoZone. I am on my 4th alternator from them (message here?), but it is too easy to jerk it off and have them test it. If it is bad, they replace it.
My problem has been a little different than yours in that my 82 seems to NOT charge when first cranked up and will not charge until it runs a bit and the engine gets a little rev up. Then, it seems to kick in and do more or less okay. But, over time, it will just get worse and at some point, the alternator will expire.
I have not been able to find any reason for this, so as long as they keep giving me a new alternator, I am in a cycle.
Buddy
My problem has been a little different than yours in that my 82 seems to NOT charge when first cranked up and will not charge until it runs a bit and the engine gets a little rev up. Then, it seems to kick in and do more or less okay. But, over time, it will just get worse and at some point, the alternator will expire.
I have not been able to find any reason for this, so as long as they keep giving me a new alternator, I am in a cycle.
Buddy
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I also have a 82 CE and it has an alternator from AutoZone. I am on my 4th alternator from them (message here?), but it is too easy to jerk it off and have them test it. If it is bad, they replace it.
My problem has been a little different than yours in that my 82 seems to NOT charge when first cranked up and will not charge until it runs a bit and the engine gets a little rev up. Then, it seems to kick in and do more or less okay. But, over time, it will just get worse and at some point, the alternator will expire.
I have not been able to find any reason for this, so as long as they keep giving me a new alternator, I am in a cycle.
Buddy
My problem has been a little different than yours in that my 82 seems to NOT charge when first cranked up and will not charge until it runs a bit and the engine gets a little rev up. Then, it seems to kick in and do more or less okay. But, over time, it will just get worse and at some point, the alternator will expire.
I have not been able to find any reason for this, so as long as they keep giving me a new alternator, I am in a cycle.
Buddy
Tell me, does your GEN light illuminate ever? Like when you start the car? If it's burned up, the sense wire won't work properly and the alternator won't charge.
You may need to test the resistance of the sense wire, or the little brown wire in the plug.
