Quote:
Originally Posted by Hotshot
A few months ago I was driving along and I noticed my 14.6 normal state was shooting up to 15.5.
New Velo OEM ALTN/Volt reg installed. Ground straps all checked good.
All seemed ok then a day later problem came back.
Started to isolate circuits. Headlights, flashers, central locking, etc, and found my seat power motor didn’t work / glitchy. Thought that motor is pulling too much and took the seat power off line.
Problem solved! Now 13.9-14.6 steady as a rock, day night, AC all good...THEN.
After 500 km since then, last night I’m driving home and I select the Vent blower at a light. So with idle power it shoots up. 14.0-15 and get erratic.
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I would think that any voltage above 14.0V is too high. 14.6V seems high to me. May be ok but seems high.
So you change the alternator/VR and get the same result? That points to the original Alt/VR are ok. Can you/Did you have the original Alt/VR checked at Autozone or whoever does that kind of testing?
Seems something other than your Alt/VR is at issue. Keep in mind that the alternator is a big inductor. If the connection to the alternator (inductor) is interrupted the alternator will react by spiking high. It would be interesting to get an oscilloscope on the battery voltage to see the actual waveform.
You like electrical work so if you don't have an oscilloscope you might want to consider buying one.
Here's an oscilloscope front end that plugs into a laptop USB port. We use this one at work.
https://www.newark.com/velleman-sa/pcsu1000/2-channel-usb-pc-oscilloscope/dp/60AC5903?mckv=s0tW4W6cR_dc|pcrid||plid||kword||mat ch|e|slid||product|60AC5903|pgrid|1234751786630905 |ptaid|pla-4580771609217368|&msclkid=3246b717d0e614a8a507d65f2c02c542&CMP=KNC-BUSA-GEN-Shopping-NewStructure-Verylow
I'll bet you have high voltage spikes on the "battery" voltage. Keep in mind that a DC voltmeter averages the voltage seen at the terminals measured.
One test would be to grab another battery and try it out. If you have a battery handy or another car, this would be an easy way to discount the battery as the issue. I had a battery that was failing and I couldn't get 13V while running. Thought it was the alt/VR. Changed the battery and got solid 14.0V.