I cut short my most recent cross country flight in my -7A because of voltage variations I wasn't comfortable with. The voltage is read at the input to the GSU that's part of my G3X system.
The alternator has about 600 hours on it after my original Vans 60A failed at about 200 hours. I had it rebuilt with more durable components at the time and it has functioned without issues since I installed it 6 years ago.
Any thoughts and ideas on its general state of operation would be appreciated. Here's what I saw:
After start, it read a stable 14.1 volts. As the power came up for takeoff, it read 13.7. During the climb to 11,500 at full power, it varied between 13.4 to 13.9. At cruise altitude, it began to vary between 13.7 and 12.9, with occasional dips to 12.5.
After 20 minutes of flight and more readings at 12.5 than I felt comfortable with, I elected to return to home base rather comtinue another 2.5 hours to destination. It never ready below 12.5 volts.
As I continued back to home base and descended with reduced power, the voltage came up and never got below 12.9. In the final 10 minures of the descent at idle power, it read a solid 14.1 and held that all the way to touchdown.
After landing, I did a full power runup and it held steady at 14.1 until nearly full static rpm, about 2350, where it dipped to 13.9. After shutdown, the battery read 13.7 initially and slowly came down to 12.9 before I shut the master off.
My mechanic's opinion is that there's nothing wrong with it on the theory that, as the battery climbed closer to being full charged, the regulator sensed less and less voltage needed to be allowed into the battery, a PC680 that is 3 months old.
A 3 hour cross-country flight a week prior didn't show readings as low, as the voltage never got out of the 13 volt range
What do any of you think?
Also, what voltage alarm parameters do you have set on your setup?
Where do you read the voltage?
Thanks in advance,
Mike
The alternator has about 600 hours on it after my original Vans 60A failed at about 200 hours. I had it rebuilt with more durable components at the time and it has functioned without issues since I installed it 6 years ago.
Any thoughts and ideas on its general state of operation would be appreciated. Here's what I saw:
After start, it read a stable 14.1 volts. As the power came up for takeoff, it read 13.7. During the climb to 11,500 at full power, it varied between 13.4 to 13.9. At cruise altitude, it began to vary between 13.7 and 12.9, with occasional dips to 12.5.
After 20 minutes of flight and more readings at 12.5 than I felt comfortable with, I elected to return to home base rather comtinue another 2.5 hours to destination. It never ready below 12.5 volts.
As I continued back to home base and descended with reduced power, the voltage came up and never got below 12.9. In the final 10 minures of the descent at idle power, it read a solid 14.1 and held that all the way to touchdown.
After landing, I did a full power runup and it held steady at 14.1 until nearly full static rpm, about 2350, where it dipped to 13.9. After shutdown, the battery read 13.7 initially and slowly came down to 12.9 before I shut the master off.
My mechanic's opinion is that there's nothing wrong with it on the theory that, as the battery climbed closer to being full charged, the regulator sensed less and less voltage needed to be allowed into the battery, a PC680 that is 3 months old.
A 3 hour cross-country flight a week prior didn't show readings as low, as the voltage never got out of the 13 volt range
What do any of you think?
Also, what voltage alarm parameters do you have set on your setup?
Where do you read the voltage?
Thanks in advance,
Mike
