Any idea what would cause the entire panel to go dark even though the battery still had a charge? I had a complete electrical failure that I was able to recover from by cycling the alternator field switch. Before the failure I think the ammeter was indicating normally. After the failure I flew about 15 minutes to an airport. During that time the ammeter showed a significant charge. A mechanic checked things out but didn’t find any problems. While working on it we were able to start the plane twice which seems to indicate that the battery still had a good charge. Anyone had this problem? Any ideas?
I can’t answer this with certainty, as it seems like it would take multiple simultaneous (but temporary) failures to exactly replicate the symptoms you described. Here is what I would do, in the sequence described, as it is unlikely that you can track it down exactly without a hard failure.
1. Check the screw connections on all of the switches and breakers behind the panel. You may be surprised how many of the screws you will find loose. If you find one or more loose on directly applicable items (master switch, alternator switch, master alternator breaker, master field breaker), that may have been your problem.
2. Check the connections on the master solenoid relay, usually located back next to the battery.
3. If you haven’t found anything suspicious by the time you get to this third item, you can replace the master relay. They cost a lot for what they are, but they aren’t tremendously costly in absolute dollars.
Ordinarily I would say that you can have a surface charge that can make a battery seem good when it isn’t, but the fact that you successfully cranked the engine twice pretty much rules out this possibility. A surface charge can run some lights and radios for a brief time, but it won’t crank the engine. I would appreciate hearing back from you on what you find on this one.