Over voltage alarm

After 70 hours of flight I got an over-voltage alarm on climb-out today. This is the first time I have had such and indication.

I have a B&C alternator with a Vr-166 voltage regulator. All new.

I also have a Scad tech high/low voltage alarm light.

Battery has been charging just fine. No previous indications of a problem. During high RPM climb-out today the alarm light came on. When I leveled off and reduced power it immediately went off. I did look a the volt meter when the alarm came on and it was reading slightly high - maybe 15 volts (analogue, so not precise).

The factory default alarm for the Scadtech is 15 volts.

B&C notes alternator output between 13 and 15 volts.

So, do I have a problem? If so, replace the regulator?

Or should I set the high volt alarm just slightly higher, like 15.2 volts, since normal charge is around 14.6?

Appreciate any opinions!

TIA
Gary

PS: Yes, this is a duplicate posting. After 100 views in in the Mx section, no one has offered a single opinion. I am hoping someone in this forum will have some knowledge on the subject.

What is your normal operating voltage in flight? If it is close to your ov detector trigger point, I would adjust the VR. Is your sense line for the vr in on the same terminal as the over volt detector? You could have a loose or poor connection at either end of the VR sense line. You may have a poor ground on the VR. I would certainly check all of those things and report back.

Bill.Peyton said:

What is your normal operating voltage in flight? If it is close to your ov detector trigger point, I would adjust the VR. Is your sense line for the vr in on the same terminal as the over volt detector? You could have a loose or poor connection at either end of the VR sense line. You may have a poor ground on the VR. I would certainly check all of those things and report back.

Click to expand...

Thanks for the suggestions! I appreciate it.

Gary

I have a B&C alternator and voltage regulator in my -4. I know from first hand experience that B&C offers excellent customer service. They have provided me with a very nice diagnostic worksheet that provides them with the data they need to help you. Several times over the years, I had issues that I suspected to be either the alternator or voltage regulator. Each time, the culprit was wiring or connection related. Finally, assuming you have a conventional lead acid battery, 15 volts seems very high. In my experience 14.3-14.6 is typical. Good luck.

Dean

Check the VR sense line very carefully. If it is "receiving" a lower voltage than what is actually present, it will tell the alternator to "make more volts" and you'll end up with over voltage.

I had an early failure of my voltage regulator due to a cracked wire (probably from vibration) right where it entered the VR. My high-voltage indicator light came on. This left me halfway to Oshkosh in the middle of Kansas where I finally found a helpful RV builder with an extra VR from a Bonanza that I wired up and flew home. story here

I ordered 2 replacements (they were <$50) and keep the extra with me in the plane at all times now. FYI - It was a Transpo F7078 model.

My alternator runs at 14.4 steady state. After start up, the demand is much higher and it runs in the upper 14's for a minute or two. When very cold outside, it will trigger the alarm and run at 15.0 for a minute or so. Within a few minutes it is back at 14.4. This is only after startup. Other high demands do not push the voltage up. The VR's are not very sophisticated circuits and I believe they don't regulate as well when the batter voltage is low or it's draw is high.

Larry