charging woes

[ehertzfeld 1]

On my diesel project, the alternator seems to be working properly, but the regulator is not. At idle is putting out 13 volts and a wide open throttle, it's jumps up to 40ish volts! Is it possible that I have the alt spinning too fast? The pulley on the alt is around a three inch and the engine is a four inch. Any thoughts?

[DMedal 1]

spinning too fast wouldn't do this. I guess if you really spun it too fast the alternator would be damaged. I'm thinking you don't have this connected to a battery as the alternator couldn't possibly put out enough current to raise the battery voltage to 40V. (and you wouldn't want to be around if it did). Check grounds and repeat test with a battery on it. Happy hunting! -Don

[ehertzfeld 1]

I had a battery installed, but did not hook up the wire that would go to it. I used my dvm to test it. Here is the set up. I guess I'll have to look for a new regulator.
[img]/club2/attach/ehertzfeld/alt1.jpg[/img]

[DMedal 1]

Elon- Before you replace the regulator, try it with a battery hooked up. Problem is your alternator has no load at all. It probably isn't putting out a steady 40V either but is tricking your DVM with a very noisy signal. With the battery on things will settle down substantially. Should the regulator indeed be faulty the worst that will happen is it will blow the fuse. (there is a fuse on the regulator output, yes?) -Don

[UCD 14]

If you are useing a one wire alt. with built in voltage reg. you need it connected to a Battery for it to work right. In reality with out it hooked to a Battery it was full fielding because there was no battery there to tell it how much charge it needed.

[ehertzfeld 1]

Ok I hooked it up and it seems to be working. Battery voltage was at 13.6 at idle and 14.8 at full throttle. The battery is one of my wife puller that we changed out in Maine, so the higher voltage makes sense to me. I only have a few more things to tidy up and she will be put into service! If all goes well, she'll be on the trailer to Colchester!:D