Alternator output voltage

[69911T]

Does anyone have the output specs for the Bosch alternator with built in regulator???
Ed

[Rick Cabell]

Ed,
It should be about 13.6 to 14.2 volts

[69911T]

Thanks Rick...I'm at 14.1 so within spec.
Ed

[SFE]

I use this old post to ask a question…

Just installed a rebuild SEV Marchal alternator in my 2.0 911E with an external regulateur
At idle I have 13.65V, but when I rev 2500 rpm or more I have a little bit less around 13.55V.

Since this alternator is under warranty I’m wondering if this is a normal behavior ?

Thanks.

[edmayo]

Yes, that's okay, it's one volt more than battery voltage.

[SFE]

I have one more question, is it normal the output voltage drops under load ?
If I put everything on I read less than 13V…
The regulator is new.

Still trying to decide if I need to send back my rebuild alternator to the shop ?

[edmayo]

An alternator can put out 18 or more volts, that's why you have a voltage regulator, I would send alternator AND regulator and if regulator is adjustable they can set it to a higher voltage. You should have 13 volts or slightly more under load. If regulator is non-adjustable and the rebuild shop supplied it maybe they can try another. Originally the regulators were all adjustable,,,then we got the cheaper solid state ones. As long as charging voltage is greater than battery voltage it should charge the battery, but at less than 13v. you're getting on the ragged edge. If the units bench test higher then you have resistances in your wiring.

[72targa]

^^^^ Yet another concise and informative description. Ed, I always appreciate your helpfulness.