[Marius]

The 12 volt alternator is likely “self exciting” it won’t put out voltage at idle rpm. You will need to get it up to 1300 to 1500 rpm engine speed to “turn on”. Once it is working it will continue to put out voltage at idle speed. The voltage will likely range from maybe 12.5 to almost 14 over the normal driving speed range.

Check it good first, they are princely in the $450 range if you need to change it out which I doubt.

[Archived]

I will try it with higher RPM’s. Thank you very much.

Marius

[Archived]

If the 12 volt alternator is not putting out charging current it needs to be rebuilt or replaced. At high idle it should easily put out 14.2

If I am right those are 145 amp alternators with the voltage regulator internal to the alternator.

May we assume it is a 12 volt coach, and that the 24 alternator handles the Prevost systems?

[Archived]

Marius,

I had an experience while in Rockland Maine during the summer of 2010. We parked with a group of Prevost owners at a combination museum and airfield. We started the generator, yes it was a dry camp experience. I had the generator serviced prior to leaving NC because of that. So we go off to lunch with all working well. Our little doggie is just happy to be in “her” bus, We come back from lunch and the generator is no longer running and the generator start battery is dead as a hammer. Fortunately for our little doggie it does not get to hot in Maine during June and the doggie was OK but glad to see us get back.

Fortunately for a couple of the other owners really liking to do repairs, the problem was diagonosed shortly after replacing the start battery. The alternator was not putting out any voltage. Big problem. Went to NAPA and best they could do was three days for delivery. They did refer me to a local repair shop specializing in alternators and generators. We wheeled into the shop in my towed vehicle right at 5:00 PM, closing time. Well, the owner was still there and he took the alternator back to run some tests. He came back and told me it would need to be rebuilt since the “brushes” were totally worn out.

Long story short, he repaired it, actually remaunfactured it with all new parts including bearings and I picked it up the next morning at 8:00 AM. Now that is service. In fact here is the shop contact information should you happen to be in that part of Maine:

Mr. Arthur Anderson

“the starter shop”

101 Western Road

Warren, Maine 04864

(207) 273-2161

Yeah Tom, I’ll make an effort to get this onto the PC Map. The Admin had to complete the first site for me.

[Andy]

I put the voltmeter on the leades and at idle I get 12.8-13 Volts.

I will try the higher RPM’s in the morning for a few seconds to get it “kicked-in” and see if I get a readout on the dash gage like I saw while driving.

What drew my attention was that I had the lights on in the coach and the engine running and the dash 12v charging/Amp gauge was showing one needle at 12V and the AMP needle in the negative territory with engine started at idle. The halogen lights do pull some amps and if the alternator was not “excited” it would make sense that all the juice was coming from the battery bank without any help from the engine alternator. While driving I was seeing 13-14 volts and the Amp needle above 0 constantly.

The Generator Alternator works fine, charges 13.5 to 14V and runs well. Just put 2 new group31 batteries in parallel and all is good there…knock on wood….

The 12V alternator is a Delco Remy 35SI- brushless, heavy duty alternator, 110-135 Amps at 12V.

http://www.newindo.com/delcoremy/30si-31si-33si-34si-DelcoRemy-alternators.htm

The 24V Alternator/generator is one year old and runs fine – 26-27V charging at high idle.

[Archived]

Mr. Joe Carter was correct…..at about 1300 rpm’s the gauge needle jumped to 14V and stayed there even at idle. All good there now, the alternator is charging the house bank. Thank you very much.

[Dick]

That’s the SI series alternator for ya. Just the way it works. I went thru the same learning curve.