[N131RV]

Friday, on the way home from Houston, my alternator warning light started flickering, then came on solid. Bus voltage remained solid at 14.2 volts.

Today, instead of going to one of my favorite places (Pecan Plantation Flyin) I decided to troubleshoot.

1. Established all wires are connected, have continuity and the connections are tight.
   
2. Pulled the cowl, verified belt tight and connector in alternator tight. Pulled connector. Tested voltage and breaker on field wire. Tested alternator light line correct. Checked connector again, put it back on.
   
3. Fired up, light still on solid, but voltage now at 14.45 (measured with meter).
   
4. Shut down, cowl up. Run the engine again, now, no output from alternator. Bus voltage at 12.9 and falls steadily (as battery discharges).
   
5. Tried toggling the field wire. Checked the field breaker, etc. No joy.

This alternator is exactly 29.7 hours since new.

Now, I have not had good luck with alternators. I have the standard boss mount setup for an IO360. My first one (vans 60 amp) made about 313 hours. Replaced with ND 14824 (plugged right in). It went about 200 hours. Replaced with same. Made about 100 hours.

Splurged for the PP, thinking it might alleviate my problem. Apparently not so.

I have checked all grounds, battery connections, solenoid etc. I fear I have a problem that is eating my alternators, but I cannot find it.

My total electrical load in VFR flight is about 15 amps. With lights on, about 23 amps. A 60 amp alternator ought to handle that with no sweat.

Suggestions welcome.

Meanwhile, I am supposed to be in Phoenix Tuesday and had planned to take this plane. From looking at the Plane Power website, it appears that won't be possible with their normal warranty service (you ship it to them and they look at it).

So, I guess I will be spending tomorrow swapping another 14824 into service. I happen to have a spare.

 

[frankh]

First one I heard of

Hmm...Now you have definately got a good ground between the alternator case and the engine right?..I only ask cus i was using painted brackets and had all kinds of problems..DOH!..What an idiot.

When you change to your spare alt, if the problem goes away its likely to be the alternator..But it it doesn't its bad wiring..And not doubting your wiring skills but this is usually what it boils down to.

I feel your pain..At least your at home and not 1000 miles away..

Frank

 

[Ironflight]

Hey Joe, since you asked for suggestions.....

I learned a couple of things here on the forums years back , when GMCJETPILOT used to post a lot about alternators. Now I am not sure of his background, but since some of his stuff checked out, I decided to follow his suggestions, and now have quite a bit of (anecdotal) experience that says he was right about a couple of things:

1) Cool the diode package! Put a blast tube pointed directly into the sheet metal housing on the back of the alternator. Safety wire it there so it blasts them directly. That package overheats, and the voltage control goes Kaput.

2) Do NOT cycle the alternator power On/Off with the engine turning over. I used to do the old routine of starting with the Battery Master on, then power up the Alternator - all "serious" airplanes used to do it that way.... But modern car alternators aren't designed to be operated that way, and powering up the alternator when it is already spinning is not good for the diodes. I can't explain why - go back and search for George's posts. But I can tell you that in the first couple of hundred hours, I operated my alternator the "old" way, and it lasted 400 hours or so. I actually thought that was good, having lost "certified" alternators on previous airplane sin that time span. But when that one died, I added a blast tube, and am religious about always bringing on the battery and Alternator switches before start - and I am now up to over 700 hours on the unit.

Your mileage my vary of course - these are my experiences with the standard ND alternators.

Paul

 

[N131RV]

Thanks

Hey Joe, since you asked for suggestions.....

I learned a couple of things here on the forums years back , when GMCJETPILOT used to post a lot about alternators. Now I am not sure of his background, but since some of his stuff checked out, I decided to follow his suggestions, and now have quite a bit of (anecdotal) experience that says he was right about a couple of things:

1) Cool the diode package! Put a blast tube pointed directly into the sheet metal housing on the back of the alternator. Safety wire it there so it blasts them directly. That package overheats, and the voltage control goes Kaput.

I had resisted putting yet another air leak in the front baffle, but I'm going to do it later today. Plane power said I didn't need one if my load was less that the rated amperage (which it is).

2) Do NOT cycle the alternator power On/Off with the engine turning over. I used to do the old routine of starting with the Battery Master on, then power up the Alternator - all "serious" airplanes used to do it that way.... But modern car alternators aren't designed to be operated that way, and powering up the alternator when it is already spinning is not good for the diodes. I can't explain why - go back and search for George's posts. But I can tell you that in the first couple of hundred hours, I operated my alternator the "old" way, and it lasted 400 hours or so. I actually thought that was good, having lost "certified" alternators on previous airplane sin that time span. But when that one died, I added a blast tube, and am religious about always bringing on the battery and Alternator switches before start - and I am now up to over 700 hours on the unit.

Your mileage my vary of course - these are my experiences with the standard ND alternators.

Paul

Yup. I always turn master and field on together on the ND. I noticed (by accident of course) that removing the field voltage DID NOT stop an ND from making power.

 

[flyeyes]

Friday, on the way home from Houston, my alternator warning light started flickering, then came on solid. Bus voltage remained solid at 14.2 volts.

(snip)
Suggestions welcome.

(snip):

I'm a little confused.

My "alternator" light is simply controlled by voltage: if the bus current is more than 13 volts or so, then the alternator must be working because the battery only puts out about 12.5.

You say the alternator light is wired correctly, but also that the voltage was steady at 14.2. I'm not understanding something

some of your electronics are probably capable of displaying their supply voltage, that can be helpful in my experience when things don't make sense.

as Paul pointed out, heat is the enemy of electronics, and since your airplane seems to eat alternators, i'd suspect they are running hot.

You can get cheap temp sensors here that you can stick on expensive stuff under the cowl to see where blast tubes might be helpful. I have them on my alternator, ignition components, fuel pump, battery, and a handful of other places. I've found them very helpful, and they have cause me to add a couple of blast tubes.

When I flew with Mike Seager years ago in the red RV6 trainer, he told me he kept spare alternators with him on the road, because the hours of slow flight killed them with some regularity.

 

[Jamie]

2) Do NOT cycle the alternator power On/Off with the engine turning over. I used to do the old routine of starting with the Battery Master on, then power up the Alternator - all "serious" airplanes used to do it that way.... But modern car alternators aren't designed to be operated that way, and powering up the alternator when it is already spinning is not good for the diodes. I can't explain why - go back and search for George's posts....

For what it's worth, the folks at Plane Power say it is OK to switch their alternators on and off. They are not using stock automotive innards (technical term). They say their alternators are "fully pilot controllable".

From their literature:

*Plane-Power Alternators are the only internally regulated aircraft Alternators that are fully pilot controllable due to our exclusive rotor wiring
circuit. Automotive alternators supply power to the
rotor by means of the output (B+) terminal. In the
case of a failed voltage regulator that is shorted to
ground the pilot will be unable to shut off the
alternator (Without turning off the Master Switch)
and could cause damage to avionics when the
voltage rapidly rises to an unacceptable level. We
believe that being able to control your charging
system in any failure mode is essential in aircraft
applications.

 

[Jamie]

My "alternator" light is simply controlled by voltage: if the bus current is more than 13 volts or so, then the alternator must be working because the battery only puts out about 12.5.

You say the alternator light is wired correctly, but also that the voltage was steady at 14.2. I'm not understanding something

Sounds like he's using the 'dummy' light (this is the way my PP alternator is wired). You supply buss voltage to a light. Connect the other terminal on the light to the alternator and the alternator pulls that circuit to ground when it fails.

 

[WAM120RV]

Concur

I have to concur with Fly eyes. Witout knowing exactly how you have wired these things it is difficult to work out what is likely to be going on.

A battery will give about 12vots, your alternator will increase the voltage to about 14-15 vots when its operating. An thats the poit your alternator seems to be working fine from the numbers you give.

So can I suggest a schematic of your wiring ( a picture is worth a thousand words) we might be able to work out the problem them But, I am thinking the alternator is Ok, theres a wiring/ground fault on your light.

 

[N131RV]

Plane power dead, replaced with ND 14824

I have to concur with Fly eyes. Witout knowing exactly how you have wired these things it is difficult to work out what is likely to be going on.

A battery will give about 12vots, your alternator will increase the voltage to about 14-15 vots when its operating. An thats the poit your alternator seems to be working fine from the numbers you give.

Yes, it was. Apparently the PP gave me an "early warning". The light came on a couple hours before it died completely.

So can I suggest a schematic of your wiring ( a picture is worth a thousand words) we might be able to work out the problem them But, I am thinking the alternator is Ok, theres a wiring/ground fault on your light.

Nope. As stated in the original article, I verified all wiring and tested it as well. The PP alternator was indeed lighting the fault light while still making power. It subsequently quit making power.

 

[WAM120RV]

Misread

Hi

Sorry, I misread your mail I thought it was still making voltage, thats why it didnt make sense to me.

Best of luck with the new one.