First off, I need to apologize for the delay. I've had an 8-week break from classes, and have been doing a lot of catch-up.
ANYwayyy... I load-tested young Skylifter's
(I am his father!) GMC alternator while full-fielding it a while back. (Okay, maybe TWO whiles back...
)
The hardest part was capturing young Skylifter:
After suitable negotiations (Protein Powder!!!) Skylifter was coaxed out of the Money Pi - I mean GMC...:
After that the handy-dandy load tester was retrieved and properly connected:
Hmmm... 14 volts at idle as per above pic... Since the Money Pi - I mean GMC was cranking slow, I put a load on the alternator down to 12.6 volts and held it there until the load tester started beeping:
Yep, sucking amps from all available sources...
Hmmm... alternator seems to be doing okay, so there are other issues. At this point, I couldn't take any more pictures because I needed at least one more arm.
Anyway, I conned Skylifter into more motor revvings (...yep, CHOCOLATE protein powder...) and stuck a nail in the test hole in the back of the alternator while I checked voltage and load a couple of times.
At 1500 RPMs voltage was close to 15, and held over 13.2 under rated (100 amp) load.
At 2000 RPMs I decided that the nail shouldn't go in the back of the alternator any more, as the voltage needle was almost pegged at 16, and the load tester was beginning to smell funny, besides emitting that annoying beep.
The load on the accessory belt/engine was noticably higher at the higher RPMs.
dcb seems to have the idea about full-fielding pretty well in-hand. The regulator is taking all of whatever voltage is being created, and sending it out through the rectifier bridge (do they still call them that???). Volts and amps are both increased as the speed of the stator through the magnetic field increases, and as the magnetic field itself increases.
At the lower RPMs not enough voltage is created to be of concern, and at idle the thing does seem to be pretty close to full-field on its own. 2K engine speed would mean something like 6-8K alternator speed, IIRC, so if a person was wanting to use an alternator for regen on a higher-voltage pack, you would most likely want to step up its RPMs for better efficiency...
