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Old 01-27-2021, 09:20 AM
ssokol ssokol is online now
Join Date: Jan 2016
Location: Cupertino, California
Posts: 118
Default From the logs...

I pulled the EMS logs for yesterday's flight. It appears that about four minutes after startup (about a minute before takeoff) the voltage climbed above the 14.1 v set point on the alternator.

At the same time, the log shows the value from the amperage shunt - which measures amps into and out of the battery - went to zero.

From that point the voltage goes up to / bounces around at 14.6 - 14.8 for the next 16 minutes. Amperage reads zero all this time.

At 2:02:50 PM, about 20 minutes after startup, the voltage suddenly jumps to 15 and then bounces between 15.1v and 16.9v. At 2:03:28 I pulled the power to the avionics bus, ending the log.

If I recall correctly - and that's a bit of an if, as I was focused on safely operating the airplane - I popped the alt field breaker to try to switch to battery-only before I shut down the avionics. If so, I don't see any indication that doing so made any difference in the situation: voltage remained high, battery amperage remained zero.

If anyone cares to look at the log, I have it posted here:

First 13 characters are the timestamp. Voltage is "vbat". Amperage is "ishunt" (multiply by 1000 to get amps).
Steve Sokol
Cedar Park, TX

RV-6A N101PR at 40XS
Open Flight Solutions - Maker Of FlightView EFIS
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