[cacflyer]

Here’s a challenge for the VAF brain trust! What might cause the ammeter to intermittently cycle during flight? I have tested the alternator which has an internal voltage regulator, it checks out. When the ammeter cycles, it is mostly going negative amps, sometimes off scale. During these events, the voltage on both busses remains steady at 14. Normal operation the ammeter shows charging (positive) immediately after engine start, then shortly thereafter makes its way to 0. On my last test, once it approached 0, it started a fairly wild cyclic going negative and approaching 0. bTW, the ammeter is from the GEA24 hooked to a G3X display.

 

[Thermos]

Just to clarify, how is the current being measured by the GEA-24? Typically that's done with a shunt that Garmin delivers with the G3X sensor kit, and if that's the case, you might want to check the wiring/connections between the shunt itself and your GEA-24. If the alternator current really was changing as the ammeter suggests, you'd almost certainly see other symptoms in your avionics.

HTH

Dave

 

[bjdecker]

+1 for what @Thermos said -- an unreliable connection between the shunt and the GEA 24. Typically it's a bad crimp on either the ring terminals or the D20 pin/sockets at the GEA 24. Could also be flakey contacts on the 1A inline fuses. One, Some, or all of these...

 

[vic syracuse]

Sounds like a loose connection somewhere on the main wire from the alternator to the main buss.

Vic

 

[fl-mike]

Loose connection. When it goes open, it will be sensed as full scale one direction or the other.

 

[cacflyer]

Thank you everyone for the suggestions on where to look. Thermos was right on, the shunt has two 1A blade type fuses, both had unseated themselves a bit. Once I reseated them and tested, the problem was resolved. Easy fix! I’ve never been thrilled with the inline blade fuse holders that I used, but now I’ve ’secured’ them using a pair of zip ties.

 

[Ralph Inkster]

It's the simple, obvious things that get you most times

 

[RV7A Flyer]

You might think about using something like this...a 1A axial fuse

Available at Digikey and other usual places. If you do, solder it in-line properly (either like a splice, with the wires soldered to opposite leads, or with the leads wrapped around the wire several times), and use plenty of heatshrink. I did the former, heatshrink on both solder joints and then one larger heatshrink over the entire assembly. It's been flawless for 1000 hours.

 

[D-Dubya]

Thanks for closing the loop on this issue so that we can all learn something.

 

[Thermos]

If memory serves, I used the B&C fusible link kit for my ammeter shunt installation. Works fine, very secure.

HTH

Dave