Alternator/Charging Question

[JMan]

So, I managed my first start over the weekend and everything looks great, except the voltage. Battery is showing 12.4 volts on my Autometer gauge and my multi-meter confirms this reading. Once started, the autometer gauge stays the same, it does not increase once the engine is running, however my Multi-meter is telling me that the system is running at 23.9 volts.

I've never seen this before. Any ideas?

Could the gauge be bad? I've never seen an Alternator put out that high of a voltage either... here is the alternator I'm running:

https://www.summitracing.com/parts/sum-810303p

[NAZ]

Hard to incorrectly wire a "one-wire" alternator so if you trust your multimeter then the internal regulator is likely the problem. Notice that one review shows that his regulator went out in less than 50-miles. And your Autometer gauge should follow the voltage spike up to whatever the max indication is. But now the question is, has the gauge been damaged by too much voltage? And what else has been damaged?

[Murd]

Try the same test on your daily driver to eliminate the multi meter as being defective but can’t imagine it is.
Don’t have much else to add beyond that.
Good luck

[j.miller]

I'm with these guys. When the motor not started you should be between 12-12.5 (so you are good there) car is running your gauge should read around 13.5- 13.7. 23.9 would boil the battery... da bat

[CNIdog]

I had similar issue with my multimeter not agreeing with my gauge. Changed to another multimeter and got another different value. Changed 9v batteries in both meters and finally got mutual readings that agreed with the gauge. Old 9v batteries were to blame. Replace those first before doing anything expensive.

[Norm B]

How is it wired to your system? Doesn’t make sense that your multimeter and gauge are not reading the same. Did you rev the engine after start? One wire alternators have a rpm sensor that turns them on and off. If you didn’t pass the rpms required to start it charging it may not have come on. If it did turn on, you may have got one with a 24 volt regulator installed. As da bat said, not good, it will boil your battery dry in no time and damage your other electrical components.

Good Luck
Norm

[rich grsc]

The alternator in the link is not a one wire, it says it's a 2g.

[RBachman]

Make sure your multi meter is set and reading properly as mentioned above. Take some readings from known sources to verify. Make sure the alternator is wired properly and there were no wires to swap around, etc.. There is a complaint (also mentioned above) regarding an over voltage on this model alternator which leans toward failure of the internal voltage regulator. What is the voltage across the battery when running? Your dash gauge should read the same. Also, while it may not be a factor, I didn't see where it was made and it wouldn't be the first time a batch of bad parts or components were imported from who-knows-where.

Regardless, if the alternator is wired correctly, you're taking readings from the proper location, and your meter is set and reading properly, there's really only one culprit. Be careful, pumping that much voltage can burn up a lot of stuff...just about anything connected to it is vulnerable.