Flashing alternator lights

[Red Air Rambo]

Originally Posted by Mark Hislop

Flashing alternator lights is not an uncommon trait in Skymasters. It is usually caused by a high resistance point in your field wiring. The regulator senses field voltage to change alternator output. A high resistance point (and it might be just an ohm or two) causes "hunting" whereby system voltage is reduced a little bit by the resistance in the field circuit, causing the regulator to boost the output of the alternator, which overshoots. this also shows up as flickering instrument lights at night.

If a volt meter shows that your voltage is changing between between 26 and 28 volts, I would first inspect every connection in the field circuit, and then the bus circuit. Don't forget to measure across your field alternator switches and circuit breakers. They are often the source of the high resistance.

Once your have the path of least resistance verified in the field circuits, adjust each VR independantly to 28.5 volts, then see if the lights stay out. If not, then look at possibly defective VR,s or a problem with one of both alternators.

As far as I know (and I'm not an expert) the OV relay will only trip on over voltage, and then it will have to be reset. It should not cause a voltage fluctuation

That's some great info....Thanks!

[Jim Smith]

Guys thanks for the replies. Mark your explanation sounds very plausable and a good place to start! And Dave I'll give Gordon a call as well. When we get this figured out I'll post the results. Jim

[Red Air Rambo]

After reading the service manual I've decided to replace the alternator field fuses as they could be the culprit. Center of the forward firewall #214 fuses. They look good but I've seen that before and still bad...old and could be the cause,,,I'll let you know if that fixes it.

Brent

[sloutitt]

In our case it was a very small short to ground in the balancing wire that runs between the alternators. Small problem that cost lots to trouble shoot due to its intermittence.
Sandy Loutitt
N81C

[Red Air Rambo]

I don't know if the alternator field fuses were the culprit or the 6 year old alternator restart batteries, but the problem is now fixed with 10 hours and not a flash.

[Jim Smith]

Well, I'm happy to report the installation of two Zeftronics regulators solved my flashing alternator lights problem. I still have a 1+- variation (less than the previous 3 volts or more) in voltage as the alternators cycle but that's probably due to some resistance in the alternator switches or circuit breakers.