Overvoltage question

I have a Plane Power alternator and voltage regulator and Odyssey battery. Beginning last May I started getting over voltage indications of 15-16+ volts. I would pull the field breaker, wait till the battery voltage declined into the upper 11's, then reset. All would be fine until the battery was fully charged again. Over the last several months the problem has become more frequent, and recently the overvoltage crowbar has tripped the field breaker a few times. I suspected a poor connection somewhere, but found none. I have ordered a new Plane Power regulator.

My question, that just occurred to me this evening - could an old battery cause this problem? My battery is 10 years old, but seems to hold charge well and cranks the engine well.

Before I simply install the new regulator, voiding its returnability, I'd appreciate opinions from you folks. Thanks!

Not sure on the plane power wiring, but 9 times out of 10 overcharging is a ground issue, as in the voltage regulator not well grounded. If it's a two field alternator, having one wire break off the voltage regulator will = runaway full field voltage. Check for a perfect ground on the voltage regulator case... zero ohms case of regulator to case of alternator.

Thank you. I did check the regulator ground wire at the regulator terminal. I measured between 0.1 and 0.2 ohms. (My Fluke meter zeros at 0.1 ohm.) The Plane Power troubleshooting guide specs 0.1 ohms, I believe (it's been a few days since I read it). I will check reg case to alt case tomorrow.

If it was me, I'd change out that 10 year old battery just because.
I had some electrical issues earlier this year, changed out my 5 year old Odyssey just because.
A cheap way to eliminate a possible issue. Or what could become an issue before long.
Turns out the problem was the regulator going haywire.
But I don't regret changing out the battery.

When you check the crimps on your connections push and pull on them. I had a gremlin I chased for 2 years, it was a crimp that allowed the cable to slide forward so when you would tug on the wire it would reseat and feel good. It would hold for a while them get loose again.
DENNY

Look at the diagram for the Plane-Power system. The wire coming from the field circuit breaker provides power to the regulator, at the 'enable' position. There is also a jumper wire from the 'enable' position to the 'sense' position, where the voltage is monitored. A poor or intermittent connection anywhere along this circuit will cause incorrect voltage output from the system. And keep in mind that this circuit should also run through one pole of the master switch, if wired correctly, although this is not shown on the Plane-Power diagram.

To do a basic trouble shoot of this circuit, turn on the master switch and make sure the charging system is powered on (engine does not need to be running here). With a digital voltmeter, measure bus bar voltage. Now measure the voltage at both terminals of the field breaker and the master switch (field power side only). Then measure the voltage at the 'enable' and 'sense' terminals on the regulator. Note ANY change in voltage from bus voltage. This will tell you what component or section of wire that is causing issue. A poor connection or any high resistance, such as a corroded breaker or switch, will cause the regulator to see a lower voltage and cause the regulator to increase the systems output voltage.

Another trick I use for these installs is to run the ground wire from the regulator to the alternator case. It's not that common, but this will eliminate any ground issues that might exist between the alternator and the airframe.

Web

Trying for a better copy of the diagram.

Web

Found a better diagram. This time it has the field circuit routed through one pole of the master switch.

Web

Thank you much. I will double check crimps and voltages as suggested. What's odd is that voltage is well regulated at 14.3 or 14.4 until the battery is fully charged. Then it starts to spike in a non-smooth manner - i.e. the voltage hops around erratically from 16+ back to 14.2. If I leave it alone it eventually crowbars out. If I pull the field breaker and let the battery run down just a bit, then upon re-energizing the field the system regulates properly again.

I will follow through with your suggestions today. If that all seems correct, will see how the new regulator behaves.

This all began at the same time I discovered a loose connection on the "downstream" terminal of the master relay (Thank you, Steve of Steve's Aircraft for helping me discover that). So I wonder if the regulator might possibly have been "spiked" by that in some way.

Well, I wiggled the wires at crimps, measured resistance to ground, and voltages as suggested. Each of those things seems right. Then flew for a little while and the system behaved. So - - I'll keep watching it, and install the new regulator, assuming the system continues to be erratic.

Is your regulator ground wire tied to the firewall or did you route it to the back of the alternator case? Cycle the field circuit breaker and master switch rapidly to break up any corrosion or burnt spots on the contacts. You've got a poor connection somewhere. Replacing the reg won't fix that.

When you do voltage checks, keep the ground lead from the meter connected to the same point for all checks. And be aware that even .1 volt drops will cause issues on a sensing circuit. I.e. bus bar voltage is 11.8. Voltage measured at the output terminal of the breaker is 11.6. This means that at operation,when the bus voltage is actually 14.2 volts as per the regs setting, the reg will only see 14.0 volts and try to increase the alternator voltage.

To make matters worse, a fixed resistance produces a higher and higher voltage drop as the current in the wire increases. Example; .8 ohms resistance will produce a drop of .2 volts if the current flow is .25 amps. If the reg senses an under voltage and increases current flow to .75 amps, the voltage drop will be .6 volts. So the greater the current draw the more inaccurate the sensing circuit becomes.

Web

Thanks Web, all of that makes sense to me, at least in principle. A couple thoughts:

The system has worked fine for 10+ years, until this summer. So it's wired correctly.

My regulator is 10 or 11 years old, and there is no "sense" terminal connection like shown on the schematic. That terminal location is labeled "N/C" on the face of the regulator and nothing is connected to it.

Compared to Buss voltage of 11.9 V, with field energized, I measured a 0.1 V drop at the "Enable" terminal of the regulator. Then I measured an additional 0.1 V drop at the "Field" terminal of the regulator. That seemed reasonable to me given that there is field current through that circuit?? My Fluke low impedance meter has a 0.1V resolution, so each of those could be .05V in error.

Alternator and regulator ground terminals are both independently routed to a ground buss which is in turn grounded to the airframe. Those ground paths measure 0 ohms.

Again, when the battery is less than fully charged, the system reliably regulates correctly (14.3 - 14.4 V). It's only when the battery is peaked (around 12.5V, in flight, radio etc turned on, with the field breaker pulled) that it gets goofy.

Am I still missing something? Thanks again for your help!

Edit: Alternator case to ground is about 7 or 8 ohms. I discounted that, assuming that the alternator ground terminal is all that really matters. Am I wrong about that?

Can you post a pic of the regulator and it's label? Never seen one without the sense terminal.

What size wire is used as the alternator ground? If the alternator case shows 8 ohms resistance to ground, it doesn't make sense that the alternator ground wire shows 0 ohms to ground as the ground wire is connected directly to the case. Maybe post a pic of the alternator case where the ground wire is connected? Should be 0 ohms from the alternator to the engine, from the engine to the airframe, and from the airframe to the ground post on the battery.

Web

This is the only pic I have right now. I will go over to the airport and try to get a better pic and answers to your questions. Thanks again...

Ok, well, I have egg on my face. Again.

1. I did NOT measure from an alternator ground post to ground. I measured from the ground terminal on the regulator, and that runs about 0 to 0.2 ohm, depending on how I hold my mouth. I'm referencing from probe wedged between copper primer line and firewall, and confirming with probe jammed into braided engine / mount strap, and from ground post on firewall. If I reverse the probes, it changes slightly - I have no idea the why on that. But my conclusion overall is about 0.1 ohm.

2. Alternator case to ground reference is about 0.8 ohm, not the 8 I previously stated.

Perhaps a good next step would be to wire directly from regulator ground terminal to the alternator case?

Here is a better pic of the regulator.

Humor me. Run the ground wire on the reg, to the ground stud on the rear case of the alternator. You want 0 ohms between the reg and alternator.

Web

Yep, will do tomorrow. Thanks!

I assume you mean to retain the lead from the reg ground terminal to airframe ground, and add a new one to alternator frame?

Edit: As has been said so many times, nowhere else can one get such timely, friendly, expert advice. I sure do appreciate.

If you run the reg ground wire to the alternator case, you can skip the reg ground to airframe. You should take a moment to clean up the engine grounds or add a good braided ground from the crankcase to the airframe.

The engine to airframe ground is hard to check for resistance. Any primer line or p-lead ground will measure low resistance but when you crank the engine, all that current needs a large ground path to return to the battery.

Web

Got it. I'll check them and clean as necessary. I have a large braided ground and a smaller 8 awg ground, each from crankcase to airframe but separate paths, like Mike MCS recommends. It seems as though the alternator frame might not be well bonded to the engine case. I'll see what I can do to check that also. Thanks again.

Also try charging the battery off the airframe. Look for unexpected voltage excursions as the AGM reaches charge. Takes 14.5 VDC plus to condition them. Them = several for me. They can become sulfated and resist charge via internal breakdown at + voltage.

Gary

DENNY said:

When you check the crimps on your connections push and pull on them. I had a gremlin I chased for 2 years, it was a crimp that allowed the cable to slide forward so when you would tug on the wire it would reseat and feel good. It would hold for a while them get loose again.
DENNY

Click to expand...

I had charging issues on my last airplane.
Took the alt off to take it down to auto-electric shop for testing.
Checked out good.
When I reinstalled it, I had to twist one wire to get it on the terminal.
I noticed that while the crimp-on ring connector pushed & pulled OK,
it turned freely on the wire.
Cut the connector off & crimped on a new one...problem solved.

Had a similar problem. Turned out to be a ground issue. Whomever mounted the alternator used vibration dampeners and the ground ran through the tension adjustment bar. Somewhere along, the adjustment bar broke but still held under tension and a safety wire. It failed finally showing arcing across the broken section. It did not have a separate ground wire to the back of the case. All kinds of testing resulted in confusion because of intermittent readings, which resulted in disassembly. Did me a favor, and is corrected as mentioned above with ground wire directly to regulator.

Well, I added a wire from alternator frame to ground terminal on regulator. The skin on the back of my hand is rearranged but.... Flew it for about an hour and a half and the voltage remained steady at 14.2 - 14.3 the whole time. So I think it might be fixed. Thanks all and especially to Web. You were right on sir!

Flew another hour and a half or so today and the voltage never wavered. Happy!

Charging issue


The video shows the Fluke meter connected direct to battery + and - while the Milwaukee Meter is connected to the Alcor Regulator ground and the alternator field terminal. There are two loads on I believe in the video with the "Alternator"/Field switch ON.





Experiencing Charging Issues:
Alcor Motorolla Alternator 12 VDC 55 Amp
InterAv Over Voltage Regulator P/N 635-62448
Alcor Motorolla Regulator P/N ?

Background on how I arrived at the issue in case it sets off any light bulbs for folks:
I performed an oil change the other day when I had a lapse in judgement and got a bunch of oil all over the place. To make clean up slightly less frustrating, I got out solvent and spray gun and figured while at it the engine could use a spray dow, etc. Thinking there is some relationship here to my issue as there was no issues prior to oil change. After solvent spray down, plane sat for 18-20 hours before taking short 30-40 min flight yesterday. Returned from short 30-40 min flight (did not observe/notice deflection of ammeter during flight- my mistake) but upon return to the airfield I noticed some audible tone/draw in my headset coinciding with the strobes. After shutdown, I thought I would check to see what was going on so I went to fire up the plane again (not entirely sure the logic behind firing up again but I attempted) and battery had been drained during flight. This battery is only 2 years old and my master relay and starter solenoid were replaced at the same time. I do not suspect there is any issues with those components.

So, I put the battery on the charger and left it overnight while I began my investigations into conductor continuity, terminals, crimps, etc. Nothing abnormal found during installation confirmation check. Aside from the dedicated conductor between the alternator and the voltage regulator, my setup is identical to the included wiring diagram/schematic. This morning I did a resistance check between my voltage regulator ground and the alternator ground terminal and found there to be 0.0 ohms resistance. I then confirmed that the Overvoltage relay positive (+) was reading the same as bus bar voltage when my master switch was on, which it was. I then checked the voltage at the field terminal on the alternator as well as at the regulator and noticed there was a voltage difference between the OVR positive(+) and the reading at the field terminal on the alternator and regulator. 12.9 or so on the OVR (+) and 4-6 VDC at the alt & reg field terminal. Keep in mind the engine is not operational during these tests. Is this expected? Should the Over Voltage Relay alter the voltage to the alternator and regulator field terminal ? If so, what is the required voltage at the alternator field input for viable operations? Assuming that it is to be somewhere in the 4-6VDC range, what would be the next place to investigate and isolate the potential suspect component? I did the same steps above while engine was running at approx 6-800 RPM and obtained the same readings.

Measure voltage at the regulator post on the alternator during engine operation? Not really sure at the moment.

Update:
I removed the original field connection at the alternator, then ran a jumper from battery to field terminal on alternator and observed +30-35 ammeter deflection so can somewhat confidently remove from doubt the alternator. Now just to determine if I’m in for replacing the OVR and Voltage regulator with something new or if I can determine if I can overcome with current setup. Any input as to ruling out OVR or VR as culprit is appreciated.

bjh356 said:

The video shows the Fluke meter connected direct to battery + and - while the Milwaukee Meter is connected to the Alcor Regulator ground and the alternator field terminal. There are two loads on I believe in the video with the "Alternator"/Field switch ON.

View attachment 56562 View attachment 56563 View attachment 56564
View attachment 56565 View attachment 56566 View attachment 56567


Experiencing Charging Issues:
Alcor Motorolla Alternator 12 VDC 55 Amp
InterAv Over Voltage Regulator P/N 635-62448
Alcor Motorolla Regulator P/N ?

Background on how I arrived at the issue in case it sets off any light bulbs for folks:
I performed an oil change the other day when I had a lapse in judgement and got a bunch of oil all over the place. To make clean up slightly less frustrating, I got out solvent and spray gun and figured while at it the engine could use a spray dow, etc. Thinking there is some relationship here to my issue as there was no issues prior to oil change. After solvent spray down, plane sat for 18-20 hours before taking short 30-40 min flight yesterday. Returned from short 30-40 min flight (did not observe/notice deflection of ammeter during flight- my mistake) but upon return to the airfield I noticed some audible tone/draw in my headset coinciding with the strobes. After shutdown, I thought I would check to see what was going on so I went to fire up the plane again (not entirely sure the logic behind firing up again but I attempted) and battery had been drained during flight. This battery is only 2 years old and my master relay and starter solenoid were replaced at the same time. I do not suspect there is any issues with those components.

So, I put the battery on the charger and left it overnight while I began my investigations into conductor continuity, terminals, crimps, etc. Nothing abnormal found during installation confirmation check. Aside from the dedicated conductor between the alternator and the voltage regulator, my setup is identical to the included wiring diagram/schematic. This morning I did a resistance check between my voltage regulator ground and the alternator ground terminal and found there to be 0.0 ohms resistance. I then confirmed that the Overvoltage relay positive (+) was reading the same as bus bar voltage when my master switch was on, which it was. I then checked the voltage at the field terminal on the alternator as well as at the regulator and noticed there was a voltage difference between the OVR positive(+) and the reading at the field terminal on the alternator and regulator. 12.9 or so on the OVR (+) and 4-6 VDC at the alt & reg field terminal. Keep in mind the engine is not operational during these tests. Is this expected? Should the Over Voltage Relay alter the voltage to the alternator and regulator field terminal ? If so, what is the required voltage at the alternator field input for viable operations? Assuming that it is to be somewhere in the 4-6VDC range, what would be the next place to investigate and isolate the potential suspect component? I did the same steps above while engine was running at approx 6-800 RPM and obtained the same readings.

Measure voltage at the regulator post on the alternator during engine operation? Not really sure at the moment.

Click to expand...

Power on, engine off, what is the voltage on the field terminal on the regulator and at the field terminal on the back of the alternator? Any difference indicates a problem with the OV module, master switch, or wiring. The 'over voltage module' is just a relay that opens at a specific voltage.

This is an Interav charging system. If you have to replace ANY component, replace the system with a Plane-Power system. You'll never look back.

Web

6.9ish volts on both regulator field and alternator field. Bus voltage = battery voltage when master switch “ON”

I disconnected the field terminal conductor at the alternator, then took ohm reading between the disconnected alt field wire and regulator field to test resistance between the two for investigating OVR issues. Reading was 0.3 ohms.

After the above, I bypassed the OVR by connecting Regulator field directly to alternator field and observed no charging or load carrying.

wireweinie said:

Power on, engine off, what is the voltage on the field terminal on the regulator and at the field terminal on the back of the alternator? Any difference indicates a problem with the OV module, master switch, or wiring. The 'over voltage module' is just a relay that opens at a specific voltage.

This is an Interav charging system. If you have to replace ANY component, replace the system with a Plane-Power system. You'll never look back.

Web

Click to expand...

Most likely a bad regulator. Here's a troubleshooting guide from an old InterAv manual. Hope this helps. (Psst! Plane-Power SAL12-70 kit, just sayin')

Web