System Voltage & Hot Alternator
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System Voltage & Hot Alternator
2001 DRV 3500 5.9
With new symptoms I’ve started a new post on previously mentioned problems.
Ever since installing an external voltage regulator years ago I keep an eye on my voltage meter fairly often every time I drive. The reading was always just above 14v idling or up to speed no matter how many accessories were on.
About 2 weeks ago it dropped to roughly 12v at both idle and at speed whenever I turned my AC on with blower on high- less of a drop registered at lower blower motor speeds). At idle across battery terminals a multimeter verified 14.3v w/AC off and 12.5v AC on high which AC setting the alternator would also get much hotter to the touch- like instant ouch.
After replacing the alternator and v. regulator I had the same problem. I took it to a supposedly good electronic auto shop paying $200 for a diagnosis. they said the blower motor was not drawing excess amps and “everything was fine”- that I didn’t have any electrical or AC issues.
The tech plugged a digital v. meter in to show me a drop from 14.3 at idle AC off to 12.7 when AC turned on high. The tech said those readings were fine.
it didn’t seem to matter to him that the voltage never dipped before no matter what was on or that the alternator could blister you in half a second. And every source I Google says that 12.7v reading is very low if not too low. Does that sound right?
Twice while trying to figure this out I was parked with AC on medium blower watching the volt meter. After about 5 min. with a good reading of 14+ volts the voltage started to climb upward quickly almost reaching the top limit of the gauge befor I shut the AC off.
The next straw I’m grasping at here is looking into the condition and connections of the wire from the external voltage regulator to the alternator telling it to increase or decrease voltage. Assuming my old and new regulators work it’s like the alternator isn’t getting the info it needs- if it’s working why isn’t the alternator boosting the low 12.7 charging volts up towards 14v?
Thanks in advance.
With new symptoms I’ve started a new post on previously mentioned problems.
Ever since installing an external voltage regulator years ago I keep an eye on my voltage meter fairly often every time I drive. The reading was always just above 14v idling or up to speed no matter how many accessories were on.
About 2 weeks ago it dropped to roughly 12v at both idle and at speed whenever I turned my AC on with blower on high- less of a drop registered at lower blower motor speeds). At idle across battery terminals a multimeter verified 14.3v w/AC off and 12.5v AC on high which AC setting the alternator would also get much hotter to the touch- like instant ouch.
After replacing the alternator and v. regulator I had the same problem. I took it to a supposedly good electronic auto shop paying $200 for a diagnosis. they said the blower motor was not drawing excess amps and “everything was fine”- that I didn’t have any electrical or AC issues.
The tech plugged a digital v. meter in to show me a drop from 14.3 at idle AC off to 12.7 when AC turned on high. The tech said those readings were fine.
it didn’t seem to matter to him that the voltage never dipped before no matter what was on or that the alternator could blister you in half a second. And every source I Google says that 12.7v reading is very low if not too low. Does that sound right?
Twice while trying to figure this out I was parked with AC on medium blower watching the volt meter. After about 5 min. with a good reading of 14+ volts the voltage started to climb upward quickly almost reaching the top limit of the gauge befor I shut the AC off.
The next straw I’m grasping at here is looking into the condition and connections of the wire from the external voltage regulator to the alternator telling it to increase or decrease voltage. Assuming my old and new regulators work it’s like the alternator isn’t getting the info it needs- if it’s working why isn’t the alternator boosting the low 12.7 charging volts up towards 14v?
Thanks in advance.
Last edited by arty4444; Jul 24, 2023 at 11:31 PM. Reason: Add info
Captain
Joined: Jul 2019
Posts: 579
Likes: 50
From: Florida
Just FWIW - I have had a very similar experience before with my van...
Additionally, my sub amp would go in and out...
I was perplexed and traced it to a loose negative battery cable...yep that was it...
Also, when I have both ACs on driving down the road, my AC inverter in the back )which does have a volt gauge) says 13.1 to 13.4 and then standard charging is 13.7-14, .
Additionally, my sub amp would go in and out...
I was perplexed and traced it to a loose negative battery cable...yep that was it...
Also, when I have both ACs on driving down the road, my AC inverter in the back )which does have a volt gauge) says 13.1 to 13.4 and then standard charging is 13.7-14, .