Re: Alternator voltage too high (+)

Jump start. Measure voltage with engine running -- 14.5V

About right, but...may be the battery not holding the voltage output back.

>Install new battery (old one 7+ years old). Drive about 10 miles. >Measure voltage with engine running -- 13.95V.

About right again, with engine running a few minutes

>Turn off engine. Voltage at battery -- 13V. Too high, right?

About right. The extra volt is surface voltage and soon drains off. You need the extra voltage pressure to push the charge into the battery

>Start engine. Voltage -- 16.7V!! Wow. Not good.

Could be correct, if you just measured the voltage at startup. Run the engine for a minute to see if the rate goes down. It may be the high initial output is a result of the drain from the starter

>This means bad voltage regulator, correct?

Solid state regultors usually work or not. There is an amazing difference in the output between regulators, meaning 10 new ones in a row may not put out a consistant rate, but have a range of rates that are acceptable.

Reply to
pete selby
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That sounds correct all the way.

The alternator spikes to replace the drain from starting the battery and the battery has a top charge after shutting down.

They both mellow out after a few minutes.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Grippen wrote:

Reply to
Mike Romain

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