New to this alternator business

I've been reading the threads on car alternators but I guess I need some more basic knowledge. Speaking of basic, I have a non-RV homebuilt in which I use a 12v battery only to spin the starter. I hook up a charger every couple weeks and have been good to go. I have a black ND generator of unknown origin. Now that the nose is off the plane for other matters, I figured I'd install the alternator. I tested the alternator at about 2000 rpm from an electric motor and with my meter's pos wire on the large post of the alternator and the meter's neg wire on any of the 3 spade terminals on the alternator I only got 2 volts DC. Today I took the alternator to the hangar so I can't provide better better information right now. What's going on with this? Its occurred to me, maybe its externally regulated and I should have tested for AC? But then why any DC at all? Does it need to spin faster with the big pulley behind the prop? Maybe the thing is just broke, and that's why someone gave it to me?
Thanks!

Field

Did you supply 12V to the alternator field while turning the alternator with the electric motor?

Don

cfiidon said:

Did you supply 12V to the alternator field while turning the alternator with the electric motor?

Don

Click to expand...

+1 Alternators need to be supplied with power for tbeir electromagnets.
You really need to get a schematic before proceeding further.
The ground return may be the case, but get a manual.

This is a nice document on alternators:

http://www.autoshop101.com/forms/alt_bwoh.pdf

Enjoy...

Nope. I was too dumb to attach a battery. VAF has "rectified" that. Thanks very much!