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woxofswa

Well Known Member
Since we had the engine R & R from the PG issue, an annoying electrical issue has arisen. I have a PP 60A alternator with Dynon SkyView. I have the shunt wired -/+ Battery load style (Diagram A I believe). I have about 3 years 300 hours on the system.

On random occasions in various stages in flight the ammeter will drop negative causing a "electrical current" alert, and then it will pop right back normal.
Sometimes the ammeter widget red exes out for a bit. This seems to happen in Odd batches as I can get three or four alerts in a short timeframe and a several flight span with zero alerts. Throughout, the voltmeter stays steady and constant.

Other than tightening the Alt belt, I haven't really dug into the matter. I did replace the battery more for routine maint than anything else. The anomaly has the feel to me of indication error, but I'm an electtard. I've thought of checking out the plug into the ALT, and replacing the dynon shunt with a more robust model but before I got too deep I wanted to query the brain trust for suggestions.

Thanks in advance.
 
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Simple things first.

Check the connections for the two sense wires going to the shunt.

Could be loose connections at the shunt end crimp terminal or at the pins going into the Skyview.

Another possibility is for bad connection on the fusible links at the shunt end, if you have them per the Aeroelectric schematics.

Pull on all of the wires and see if one pops out. :)
 
I bought a new Alternator ( built in Voltage regulator)for mine but that is not the problem. Turns out mine was the mv sensing wires that take the amp signal to the Dynon . There are two small wires across the shunt that sense that amp capacity. These wires sometimes either work lose or have a bad connection and give you a false indication of amps. Doesn't take much to create additional drop in a mv signal. Could be positive or negative depending on where the bad connection is. Check those before you go any deeper.
 
You're probably on the right path, thinking indication error. If the voltage is nominal (~14.2-14.5volts) and isn't changing, then your alternator is doing its thing properly. Current variations are likely happening elsewhere, or not at all (indicator issue).

To be realistic, once you've used an ammeter initially (before 1st flight) to measure the actual current draws of each component (to plan for load shedding in the event of alternator failure), an ammeter is possibly the most useless weight in the aircraft. An alternator failure will cause either over or under voltage (read on the voltmeter and hopefully, announced). Any device failure that causes increased or decreased current use big enough to raise a red flag is going to make itself known by its failure; if it's not completely dead it will just be a distraction trying to find out what (if anything) is actually causing the indication.

Charlie
 
In the installation of my Dynon180 it recommended to also install small fuse and fuse block on each of the shunt sensing wires. I did and had forgot about them. Had used an incorrect size lug crimped onto the small 22 gage wire at the fuse block was the problem. I had two that easily pulled out of the lug on inspection. But it performed flawlessly for 7 years and 500 hrs before showing up.
 
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