Over voltage!

[dmevans]

Hey everyone,

I took the plane out yesterday headed to the coast. About 15 min into the flight, I got an overvoltage indication on my EI panel. The voltage was fluctuating between 14.5 and 15.5. It seem to do this regardless of RPM. I took the cowls off once I landed to have a look around. I thought I may have a bad ground, loose wire, etc. I wasn't able to find anything. I cowled everything up, fired her up, and everything was back to normal 14.2 volts solid on taxi. Did a runup 14.2 solid. Went up for a local flight and everything was normal until about 10 minutes into the flight. Volts started fluctuating again!! I'm thinking it may be the voltage regulator, but I am not certain. I have an InterAv system with the alternator STC.

I attached a video of the voltage fluctuation, but it's hard to see due to the display. This was taken after I landed, parked in front of the hangar at approximately 1,000 RPM

https://photos.app.goo.gl/aTHewwXAUeGjoXPY2

Any help is greatly appreciated guys!

 

Thanks. 

 

[DonMuncy]

Sounds like the voltage regulator. Simple enough, and cheap enough to use as a diagnostic tool. Zeftronic regulators are the way to go.

[RobertE]

I bet it’s the voltage regulator too.  But I had a similar problem earlier this year.  It turned out to be a loose ground on the alternator.  My guess is that the intermittent charging sometimes produced a voltage spike.  So it can’t hurt to check that out before moving on to more expensive repairs.

[Andy95W]

For the Interav alternator conversions, really the only STCed replacement is the Plane Power:

https://www.aircraftspruce.com/pages/el/voltagecontrols_regulator/planePowerSAL2.php

It is top notch, and unlike the InterAv setup, completely controllable and self-contained so you get rid of the big capacitor on the firewall.  It costs less than $200.  Even if it turns out to be something different, it is definitely an upgrade to the system.  The InterAv alternator itself is pretty bulletproof and can be overhauled relatively cheaply.

If it was me (it actually was me 6 years ago!) I would order and install the PlanePower voltage regulator and check all the wiring from the regulator to the alternator.  Repair anything that has an old or ugly connection.  Set the voltage to 14.2 volts.  If the overvoltage happens again, send the alternator out for overhaul.

Good luck, please keep us posted.

[ArtVandelay]

I would clean the voltage regulator,alternator connections, if there is a poor connection it would not be able to sense voltage correctly (it would appear lower). Get electronic cleaner and pull apart and clean any connections.

[Piloto]

It is kind of hard for an alternator or alternator to output 15 volts or higher under load at 1,000 rpm or less. Check voltmeter ground sense connections. Check with another voltmeter connected to the cigarette lighter.

José  

[TheTurtle]

On 2/22/2018 at 9:20 AM, DonMuncy said:

Sounds like the voltage regulator. Simple enough, and cheap enough to use as a diagnostic tool. Zeftronic regulators are the way to go.

my zeftronics lasted about 6 months.  Support was a pain in the ass.  They finally gave me an RMA number.  Been a year still havent gotten my money or another voltage regulator.  I just bought a Plane Power so when theres a problem the alternator people cant blame the VR and the VR people cant blame the alternator.

[DonMuncy]

Sorry to hear that. My VR is going strong after several years. Glad I haven't had to try to find out if your experience is typical.