I've got the Plane Power SAL 12-70 alternator in the Skywagon, it just started popping the field alternator CB anybody have a similar problem in the past and a possible remedy? I've been watching Voltage and it seems normal 14.3-4 but I've not seen the volts when it pops.

Voltage regulator?

That kind of stuff is frustrating.

Glidergeek wrote:I've got the Plane Power SAL 12-70 alternator in the Skywagon, it just started popping the field alternator CB anybody have a similar problem in the past and a possible remedy? I've been watching Voltage and it seems normal 14.3-4 but I've not seen the volts when it pops.

Check all of your terminals and especially wiring. If there is any chaffe in a wire where it bends around a corner or any place it has rubbed thru, your breaker pops. I've seen wires that have Adel-clamps around them chaffe eachother and its not visible until you loosen them. Terminals will sometimes loosen and contact some ferrous part and ground too.

Planepower also has tech folks that will cheerfully help out if you've exhausted your fault-isolation.

I'm a novice at this kind of stuff, but I recently watched Mike Busch's webinar on alternators. His trouble shooting steps seem straight forward and in a logical sequence. Hope this helps.

http://www.eaavideo.org/video.aspx?v=1549006054001

FWIW I just replaced the alternator in my old Toyota 4wd pickup-- $86 out the door from NAPA (not counting $50 core charge). Wish airplane alt's were that cheap. Pretty small & light too.

Grassstrippilot wrote:I'm a novice at this kind of stuff, but I recently watched Mike Busch's webinar on alternators. His trouble shooting steps seem straight forward and in a logical sequence. Hope this helps.

http://www.eaavideo.org/video.aspx?v=1549006054001

Thanks all, bad ground The ground wire that goes from the regulator to the firewall had a bad connection and It was showing the wrong value in the resistance and when I tugged on it the wire came out of the connector. Before in-flight I was always showing about 14.2v to 14.4 v On the JPI 700. After the fix I was showing a consistent 14.0 v On the JPI In a consistent 13.6 at the cigarette lighter With one of those little digital readouts that plugs into the cig lighter.