cheeselion
Member
Apologies for the newbie question. I bought my RV-4, and I'm still getting familiar with the intricacies of the electrical system.
Is it normal for alternator output (or bus voltage) to vary with ambient temperature?
I went flying yesterday to warm it up before changing the oil. Everything electrical seemed normal. Resting voltage 13.2V (EarthX battery), with the alternator on it was charging at 14.something V.
Came back in and changed the oil. By the time I was getting ready to run it again to check for leaks the temperature had dropped to probably 2-3C. Running it with the cowling off, the alternator seemed to be outputting 15V! My EarthX warning light didn't come on but I shut it down pretty quickly. Actually, first I switched off the alternator master which brought the voltage down a bit, but not immediately to 13.2V, which I thought was strange. I would have thought de-energising the field would cause it to drop immediately.
Is the high voltage an expected effect due to no cowling and cold air? Or am I starting to see alternator issues?
It's a 35A IR automotive alternator with a Zener diode for OV protection.
Is it normal for alternator output (or bus voltage) to vary with ambient temperature?
I went flying yesterday to warm it up before changing the oil. Everything electrical seemed normal. Resting voltage 13.2V (EarthX battery), with the alternator on it was charging at 14.something V.
Came back in and changed the oil. By the time I was getting ready to run it again to check for leaks the temperature had dropped to probably 2-3C. Running it with the cowling off, the alternator seemed to be outputting 15V! My EarthX warning light didn't come on but I shut it down pretty quickly. Actually, first I switched off the alternator master which brought the voltage down a bit, but not immediately to 13.2V, which I thought was strange. I would have thought de-energising the field would cause it to drop immediately.
Is the high voltage an expected effect due to no cowling and cold air? Or am I starting to see alternator issues?
It's a 35A IR automotive alternator with a Zener diode for OV protection.