output voltage of an alternator?

[Fullmetal Chocobo]

Is there a standard voldtage for charing the batterieis in a car? I'm guessing it would be the alternator output voltrage, but I'm not sure.

EDIT: This is going to be for a solar panel mod, so I need an accurate as possible measurement. If someone could check with a DMM, that would be awesome, but I have no idea if that is even possible.

 

[Gillbot]

The standard output of an alternator is usually rated at 14.7 volts.

 

[Gneisenau]

13.6 at the low end. 15.2 at the high end. But Gillbot is correct, 14.7 is the prefered voltage. At least these were the limits when I was a mechanic. (Which has been a few decades now....) I don't think car batteries have changed much since then though....

 

[IGBT]

Originally posted by: Gillbot
The standard output of an alternator is usually rated at 14.7 volts.

..is that pulsating dc?

 

[Analog]

Originally posted by: IGBT

Originally posted by: Gillbot
The standard output of an alternator is usually rated at 14.7 volts.

..is that pulsating dc?

The output of an alternator is 3 phase bridge rectified. So its liked the chopped up tops of sine waves. Pulsating in that sense, not a PWM or square wave. Typically you don't see this because it is connected to a battery, which tends to act like a large capacitor and smooths between them. If you had one on the bench, w/o a battery on the output side and a field voltage available, you'd see what I'm saying.

 

[LTC8K6]

http://jaguar.professional.org/phpsine.php?0

Won't be that clean, but that gives you the idea. The 3 phases with the yellow being the rectified waveform.

 

[jtvang125]

Don't alternators initially generate AC voltage and then converted to DC?

 

[LTC8K6]

Don't alternators initially generate AC voltage and then converted to DC?

Yes, that's essentially what analog said.

 

[Fullmetal Chocobo]

Excellent -- thanks for the info. Would 14.7 VDC be abel to charge a standard car battery, and is there any kind of float charge capability?

 

[Gillbot]

Originally posted by: Fullmetal Chocobo
Excellent -- thanks for the info. Would 14.7 VDC be abel to charge a standard car battery, and is there any kind of float charge capability?

You can charge a standard car battery with less than 12v but you won't get maximum life. I keep a car battery as a hackjob UPS and it gets supplied with 11.88v. It runs my PC for hours without an issue.