Alternators off line

[Cloud9sa]

We received the replacement voltage regulators from Don Niesser and installed them, but the problem remains. We get a high voltage warning indication, kicking out the alternators, occasionally when we cycle the gear or cowl flap motors on the ground (with a battery charger attached to the battery), but the problem happens most of the time when they are cycled in flight. We checked all the switches and relays in the landing gear and flap motor circuits, and they seem OK. In addition to getting an intermittent high voltage indication when the cowl flaps or landing gear (down) switches are actuated, sometimes the gear doors don't close when the gear legs lock into place, suggesting low voltage. We have a digital system voltage readout, and it does not indicate high or low voltage, just normally 27.7 v. Any ideas? Faulty overvoltage sensor? Something causing instantaneous voltage spikes and dips when switches are actuated? Thanks, Tracy 1977 P337G

[jhickam]

I have had the same problem and I am thinking it is a bad master relay. My problem is very intermittent maybe three time in the last two years. The problem appears to go away with more use. I will changing mine out at annual the 1st week of March. I will let you know the results.

[Jerry De Santis]

Hi Tracy

A battery not up to par will do some strange things on a skymaster. Before you go wild checking out everything, A new battery is the best thing to do since in general, they should be replaced more often than you think. On average, I get about 18 months of useful battery performance then I get a new one to avoid things you are experiencing.

The voltage reg could be checked out very quickly. Just keep one alt off line. If the problem continues when you test each that way, then it is not the volt. Reg.

I suggest a new battery

Good luck
Jerry
BTL

[Ernie Martin]

I agree with Jerry that the battery is often the problem. I get more like 3 years on mine, but I "recondition" them every 9 months or so. Take it out, fill as specified with distilled water (you will find several cells way low), then trickle charge overnight at the 2 amp rate. Most 24V chargers have an automatic 2 amp rate.

I actually go further. I downloaded the online battery charging directions from Gill, read that there is an optimum voltage that should be maintained during the trickle charge, and (after some calculations and testing) devised a line of resistors (bought from Radio Shack) that I put in line between the battery and the charger. I do it during the day, rather than overnight, and as the battery charges I measure voltage at the battery posts and adjust the resistance to provide the optimum voltage. In the first 4 hours or so, I measure and change resistance roughly every hour, then make a final resistance adjustment about 3 - 4 hours later, then there is no change needed thru the final 6 hours or so.

Gill and others sell constant-voltage chargers that do this automatically, but they are expensive. With $5 of resistors and a little TLC I accomplish the same thing.

Ernie