Charging Troubles

[DaveH]

Our group-owned PA22 Tri-Pacer dynamo doesn't cut-in until about 1400 rpm, which surprised me when I first flew it. However the other group members tell me that's normal. It also has a tendency to go up to about 16 Volts at odd times, which also surprised me, and sounded a bit on the high side. Just recently another member had the low volt light come on during a flight, and the system was 'looked at'. Whether much more was done than looking I'm not sure, but when I flew it the other day on a short local flight, it came on again at cruising rpm (around 2300) but went out again when I put in a short climb at 2500, and stayed out for the rest of the flight until the revs dropped again on landing.

I'm a fairly low-hours pilot, but have a long experience with old VWs with dynamos and I suspect the voltage regulator is getting tired. Are there any specific checks that could be done to save replacing things that may not be the problem?

If it's the regulator, where are these available from now? The aircraft is a 1953 model PA22-135 but it's had a newly rebuilt 150hp engine fitted fairly recently. I don't know if the ancillaries were changed, but I suspect not. It's quite possible it may not still have the originals though.

Thanks for any help and reassurance.

[P.o.P.]

Get someone that KNOWS generators to look at it.

The Regulator may just need PROPER adjustment.

16 volts is HIGH.

1400 to cut in in about right.

It is NOT an Alternator as in newer systems.

One often overlooked area on PA22's is the Master Switch.

It is a Double Pole switch .

In addition to turning on the battery it also does likewise for the Generator.

The Regulator controls the Generator via "Field Current" & this has to pass through the Generator

Portion of the Master Switch.

Any corrosion or resistance on these switch contacts will give erratic Generator output.

[DaveH]

Thanks P.o.P. The master switch is a toggle switch and not too accessible, but there could be a problem with corrosion I guess.

[P.o.P.]

You could disconnect the battery & check with an Ohmmeter.

[Steve Pierce]

I have downloaded the Delco Remy Voltage Regulator Service Bulletin I use. Normally a generator will work or won't work if the regulator is good, in other words a bad generator isn't usually intermittent. Below are the regulators that work on or 20 amp generators.

Voltage Regulators- 20 amp
Kelly Aerospace
VR300-14-20

Delco Remy
1118736
1118904
1119226

Zeftronics
G1200N

The Delco Remy generators on our Pipers is referred to as a "B" circuit where output voltage is controlled by regulating the battery to the field. To test the generator remove both the armature and field wires from the generator and be sure and insulate the wires so they won't touch anything. Connect the field post to ground and hook the armature post to the plus side of a DC voltmeter. Connect the negative terminal of the DC volt meter to ground. Start the engine and the voltage should go up as you advance the throttle. I have also seen people hook a battery to the generator basically making a motor out of it.

Be sure and disconnect your wiring and check it as well. I had an armature wire that was grounding out through the shield recently that took me a while to find.

The generator is a reliable piece of equipment and relatively cheap since they are lying around from people removing them for alternator conversions however they don't start charging until reaching 1200-1400 rpm which has been a problem for me while taxing around at night with my taxi light on.

[Frogdad]

I had exactly the same symptoms. 1953 PA-22/20 135. It would not cut in until about 1400 or 1500 then voltage would follow RPM until it hit 16 or so volts at full power. Had to turn on the landing light to keep the voltage down and not fry the radios. Tried adjusting the regulator but had no luck.
Replaced with Kelly Aerospace VR300-14-20. Now it works perfectly. Cuts in about 1100 then stable voltage throughout RPM range. Only cost about $130. Cheap repair compared to fried radios.

Good luck. 16 volts is too much!

Don

[Gilbert Pierce]

16 Volts will also cause the batttery to gas, over-heat and blow battery acid on your fabric belly.

[DaveH]

Thanks for all your helpful advice. The regulator has been adjusted so hopefully that will do the trick.

[45-70]

I would like to get a new voltage regulator for my plane. I found the below list in another thread of compatable part numbers.
It doesn't seem like the Kelly or the Zeftronics are approved for the PA-22. Anyone know the details of this?

Also, if this were an "Experimental Tripacer", Does anybody know the NAPA part number equivalent to the original mechanical unit?

Thanks for any help.




From other thread
___________________

Voltage Regulators- 20 amp
Kelly Aerospace
VR300-14-20

Delco Remy
1118736
1118904
1119226

Zeftronics
G1200N

[Bob Ohio]

this is a cut from a prior thread "Charging Woes" on this site 07/2011, started by a owner with generator regulator problems, this is from post # 52, a solid state replacement for the Delco generators listed available from Air Spruce. Bob 52 Tri Pacer

Post # 52
The picture you posted is a Delco-Remy 1118736 20 amp voltage regulator for a 20 amp generator.
Here is a solid state replacement.
http://www.aircraftspruce.com/catalo...tronicsreg.php

Halfway down the page is the solid state replacement for your Delco Remy 1118736 voltage regulator.