I have a 1985 winnebago motorhome. Chevy truck, 454 eng platform. The alternator seems to work OK but when you rev up the motor the voltage gage is pegged at 18 volts. I turn off the motor then restart and it works OK until I rev it up again, Same thing happens. I have replaced the alternator. The truck battery in not new...
Any suggestions??

At idle rpm, the regulated battery voltage should be 14 to 15 volts:

https://www.askmehelpdesk.com/cars-t...ml#post1973613

Check the results with your multimeter--there may be an issue with the truck's gauge.

Quote:

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Originally Posted by TxGreaseMonkey

At idle, the regulated battery voltage should be 14 to 15 volts:

https://www.askmehelpdesk.com/cars-t...ml#post1973613

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Yes, but this alternator is putting out way too much. 18v is the limit on the gage, it is probably higher, but the lights glow so brightly that I am afraid of burning something up. This is an overvoltage situation.

That's why I suggested testing the alternator with your own multimeter. If it still exceeds 15v, replace the voltage regulator or alternator again and/or have the PCM tested. Also, test or replace the battery--there may be something funky going on that causes the system to overcharge. I'm sure, by now, you have cleaned all connections.

Thanks for your input. I will check those things and let you know...