Driving to work this morning and the volt meter slowly dropped from 12 to 9v and then the car died. Suspected bad alternator.

I bought a new battery and drove home before it could die again, volt meter again started at 12v and slowly dropped.

Made it home and grabbed all my tools to remove the alternator, went to move the car into a better location and BAM, charging at 14.4v

Start and stop the car a few times and still charging ok

Any ideas? Seen this before?
Can the Alternator have intermittent problems. Is this a rectifier or regulator issue that can be intermittent?

Thanks All

 

An intermittent connection somewhere?

I'd look for loose battery cables. Both cables, both ends. Also look for corrosion or frayed.

Also remove underdash alternator fuse and slide back in couple times, to wipe clean contact surfaces. Could be corroded fuse.

 

The internal voltage regulator may be on its way out hence the intermittent voltage production. That or tensioner/belt needs replacing