Alt Circuit Breaker Popped Twice Yesterday

[ve6yeq]

@Cactus Charlie see link below. I’m working to download the actual data file and will post that up too.

SavvyAviation

apps.savvyaviation.com

From what I can make of the numbers, I would have to guess that something caused a loss of alternator voltage regulation and then an overvoltage shunt somewhere tripped the breaker. The one-second sample rate on the logs would not be fast enough to capture the actual trip event.

I am not familiar with the xcub electrical system, but it looks as if you have a lead acid main battery that is not in great condition from the amount of main bus voltage drop when the alternator dropped offline. Does the AMM that comes with the Xcub have the wiring schematics in the back?

 

[Neal]

@lrobichaux - the coil packs are part of the electronic (light speed) ignition system but I have no clue what's used in your plane, and quite frankly, stop at I have no clue.

Any talk with Pete on a warranty replacement of the push-pull breaker? That's the most expensive one in the plane so I'd see if CC can send you one. It's rare but breakers do go bad too. Also check wires on the breaker. My IBBS wire came off the breaker which caused a 6 month hunt for the "IBBS in use" message on my G3X until I noticed a pink wire dangling one day looking under the panel. I found a screw on the floor which I saved and then the puzzle came together. So check the security of the wires at the breaker as well.

 

[lrobichaux]

I am not familiar with the xcub electrical system, but it looks as if you have a lead acid main battery that is not in great condition from the amount of main bus voltage drop when the alternator dropped offline.

It has an EarthX ETX 900 vented LiFePO4. Seems to be in good shape, as I keep it connected to the proper battery tender.

Does the AMM that comes with the Xcub have the wiring schematics in the back?

CC has sent me all the wiring schematics.

I would have to guess that something caused a loss of alternator voltage regulation and then an overvoltage shunt somewhere tripped the breaker.

I'm not an electrical engineer, but your guess seems spot on to me. If this pattern repeats, I'll be filing a warranty claim for a new alternator.

 

[lrobichaux]

So check the security of the wires at the breaker as well.

Excellent suggestion!

 

[Cactus Charlie]

I looked at the data and it is consistent with an intermittent short to ground of the alternator output . This short must be down path of the CB and current sensing shunt.

Of general interest - the NX (at least this NX) instruments alternator current, not battery current, so not the same as EX-3 or FX-3.

 

[Cactus Charlie]

If this pattern repeats, I'll be filing a warranty claim for a new alternator.

Nothing wrong with the alternator but you may run up a few hours of labor if you pay someone to find the intermittent short circuit.