Alternator Problem??

[Peetie the Pilot]

Hi RV Community
I am looking for an answer to a problem I had today flying back from a fly-in. I slowly started to lose some of my electrical components that are hard wired to my panel. First one GPS failed with a "lost external power" warning window and then the other GPS gave me the same thing and finally the XPDR quit. I shut all electrics off and slowly put them back on line. I also shut the field switch and ran on battery power every 10 minutes and then turn on the field back on for a few minutes. I alternated this practise til I landed back home. Now the ammmeter would show a -8 or -9 draw when the field switch was OFF ( drawing from the battery) and +27 to +33 when I would put the field switch ON. Has the regulator gone on the rear of the alternator or should I be looking at something else.
I thank you in advance for your answers.

Peter Marshall
RV9A
C-GRVN

 

[Ironflight]

Peter - did you get a voltage reading in either condition? I find that to be a much more useful parameter than amps when troubleshooting alternators. Also - what alternator do you have?

Paul

 

[Peetie the Pilot]

Peter - did you get a voltage reading in either condition? I find that to be a much more useful parameter than amps when troubleshooting alternators. Also - what alternator do you have?

Paul

Hi Paul
I have the Nippondenso 60Amp version which were shipped in 2002. Yes I was getting voltage readings between 11.5 to 13.1 volts.
Thx
Peter

 

[PCHunt]

Hi Paul
I have the Nippondenso 60Amp version which were shipped in 2002. Yes I was getting voltage readings between 11.5 to 13.1 volts.
Thx
Peter

Hmmm, at 11.5 volts, it looks like battery voltage only, and at 13.1 volts, maybe the alternator was working. Alternator should put out 13.8 to 14.5 or so.

Just wondering if the voltage changes were gradual or "sudden"?

 

[apkp777]

If it were me, I would start by making sure I had 12v to my alternator field. My guess is that you don't. If not, then trace back from bus to switch to alternator to find the "OPEN". If you do, I would suspect the alternator or related connections. It's easy enough to pull the alternator and have an auto shop bench test it. Make sure your cooling blast tube is installed effectively.