R

rwarre

Well Known Member
Installed a new alternator and battery. Alternator was bad and the battery was getting weak. Both were exact replacements. When I did a test run everything checked out Alt. Putting out 13 volts. Flew from Colorado to Rock Hill SC. During the trip upon startup, I experienced an immediate shutdown and restart of the efis and radios. I notice low voltage once and increased the rpm, that seemed to help the problem. At my second stop 5miles from the airport all the electrical systems failed but I was able to restart them and land safely. On the last leg , I turned off my back up battery switch and had no trouble. I will be checking gound wires and connections before I start back to Colorado, but would like to hear any troubleshooting suggestions.
 
Sounds like a good place to start, looking for loose connections. The alternator should be putting out 13.5 to 13.8, IMO, but that could be a problem with accurate sensing due to loose connectivity. You'll need a good multi-meter to get to the bottom of the problem.
 
Based upon your description and the recently failed alternator, I suspect a wiring problem (e.g. loose connection), possibly in the B lead, sense lead or ground of the alternator. You need to do some more detailed troubleshooting with an ohm meter on the entire charging cricuit, including the ground path. The fact that switching to a backup battery resolved a "failed system" (somewhat vague - assuming 0 voltage) tells me something broader and more troubling in play as well. Voltage dropping from 13.8 -> 12 is a charging circuit issue. Having your EFIS and radios reset is something all together different and will require some deeper troubleshooting. I can't help without a better understanding of your dual system and components used to build it. That is going to need someone testing and exploring on the plane, I believe.

If you chose to fly it home, be certain that you have VFR all the way and carry a fire extinguisher or two. Something of significance seems to be happening and it could result in a full electrical system failure. By complete I mean backup as well.

Larry
 
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Be sure to check the ground strap to the engine and the main contactor connections/crimps/breaker or ANL fuse, etc. for security. The avionics should work down to 10V or below. Sounds like an intermittent open/break in one of the main connections. Don't forget the wires and switch that control the contactor.

Power up the main bus on the ground and start wiggling and tugging on wires while someone watches the displays.

Good luck!
 
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