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High voltage

bob888

Well Known Member
My charging voltage shows 14.9 - 15.1 volts in cruise flight. I have the standard Vans 60 amp internally regulated PLane Power alternator. I guess the question is whether this is a problem or not. Electrical system seems happy so far. I assume the voltage reading is correct; G3X engine monitor.
 
Yes, this is a problem.

Suggest you first connect a simple multimeter and verify your engine monitor is accurately reading buss voltage (you need not run the engine, just compare the readings). If so, repair or replace the alternator.

Carl
 
Plane power alternator

You've already received the correct advice of verifying with a multimeter.

On a side note the 60 amp plane power alternators have not been enjoying a great reputation for reliability. A survey on here indicated that about 1/3 of them fail with less than 300 hours. Mine failed somewhere around 240 hours. I had it repaired by a local autoelectrics shop. So if you feel the need to remove it any automotive alternator repair shop should be able to bench test it for you.
 
IIRC (and it?s quite possible I don?t) the internally regulated PP senses buss voltage off the field circuit line. Make sure there are solid connections, low resistance CB, etc, on that line/connection, too.
It?s almost as if you have one diode worth of voltage drop in that line.
 
Voltage is measured as a reference to ground. Verify your engine/alternator are properly grounded.

IIRC (and it?s quite possible I don?t) the internally regulated PP senses buss voltage off the field circuit line. Make sure there are solid connections, low resistance CB, etc, on that line/connection, too.
It?s almost as if you have one diode worth of voltage drop in that line.

Two excellent suggestions as the place to start.
 
Before you convict the alternator, verify that you do not have a significant voltage drop across the field wire. As pointed out in an earlier response, the voltage regulator uses the field terminal to determine the regulated voltage. If the field wire, CB, or switch, has too much resistance, a voltage drop will develop across that path, which will result in the VR thinking the voltage is too low and increase it's output voltage. The first step would be to measure the voltage drop across the path of the field circuit. You could also remove the field wire and temporarily run a new 18 gauge wire from the battery to the field terminal and run the engine and see if that fixes your issue.
Having said that. My PP alternator lasted less than 400 hours before it was replaced with a Band C.
 
Also check the connector at the alternator. There?s an extensive thread about that.

If it ends up to be a failing regulator, here?s the Aircraftspruce part numberr for a replacement:
07-17968

Lenny
 
After reading all the above and checking accuracy of my voltmeter (within .2 of test instrument), I did what I should have done first. A review of the Odyssey spec sheet showed ideal charging voltage 14.7 and normal range 14.2 to 15 volts. I guess I?m OK... Thanks to all for their input.
 
Just because one thing is good, doesn't mean all is well...

After reading all the above and checking accuracy of my voltmeter (within .2 of test instrument), I did what I should have done first. A review of the Odyssey spec sheet showed ideal charging voltage 14.7 and normal range 14.2 to 15 volts. I guess I?m OK... Thanks to all for their input.

I was just going to post that Odyssey's do indeed, according to their literature, like higher voltages than other batteries. However, and this a BIG however, Plane Power regulators are to my understanding set for less than that. If your plane power is actually producing that, then something is wrong. This was what one of the things I saw at the beginning of my Plane Power failure as well.
 
And you forgot to look at your avionic supply voltage specs. 15vdc is too high.

Your alternator voltage regulator is going south.

Carl
 
Alternator

Also check the connector at the alternator. There?s an extensive thread about that.

If it ends up to be a failing regulator, here?s the Aircraftspruce part numberr for a replacement:
07-17968

Lenny
The spruce pn took me to a list of Hartzell parts that must be over 200 items. No order to the list. I tried several months ago to get info from Hartzell about high voltage. Their "customer service" for alternators is non existent. An avionics shop that I trust told me that 15v will not hurt my Bendix King avionics.
 
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