Alternator woes

[Gary Bricker]

Go with Plane Power. You don't have to worry about the "run away" which destroys the old style from Vans. I think vans is buying Plane Power now as well as Aero Sport Power. My IO 360 came from Aero Sport with one on it.

[f1rocket]

I don't see that much of a price difference between the Plane Power 12 volt 60 amp alternator ($569) versus the equivilent B&C alternator ($595). However, the Plane Power does come with it's own internal regulator.

[rvator51]

Originally Posted by f1rocket

I don't see that much of a price difference between the Plane Power 12 volt 60 amp alternator ($569) versus the equivilent B&C alternator ($595). However, the Plane Power does come with it's own internal regulator.

It's a lot cheaper if you buy the Plane Power alternator from Vans. $375
http://www.vansaircraft.com/cgi-bin/...alternator-kit

[f1rocket]

That darn Van sure knows how to negotiate a discount!

[Rick6a]

Originally Posted by rvator51

It's a lot cheaper if you buy the Plane Power alternator from Vans. $375
http://www.vansaircraft.com/cgi-bin/...alternator-kit

Now that's what I call a freaking relief. Reading through this thread, I kept saying to myself..."What's Plane Power...what's Plane Power"? Turns out that's what I ordered out of Van's catalog and is on the way via UPS ground...should be here late Monday. First time I've really been grounded for a groundable reason. Should be flying again on Tuesday. You really don't know how much you miss your RV until you can't fly it!

[gmcjetpilot]

Originally Posted by jcoloccia

Just one note about the crowbar overvoltage protection. It's not a Rube Goldberg approach but common and accepted practice. The point of the crowbar isn't to trip the circuit breaker. The crowbar immediately shorts to ground, quickly and completely removing the field.(?) The circuit breaker then trips to keep you from burning up the wires. (If you are talking about an internally regulated alterantor this is 100% not correct. If you are talking about an externally regulated alternator, you are kind of sort of correct, but the KEY are the words SHORTS and TRIPS the CB. I don't want to get into the knee bone is connect to the leg bone, BUT the FIELD gets it power thru the voltage regulator and will do so until power is cut off. The shorting of the crow bar does NOT remove power to the field, it only LOADS DOWN the alternator. If the CB does not TRIP that wire from the CB to ground thru the crow bar will GLOW RED HOT, SMOKE and melt like a chocolate kiss on the glare shield of a black car in Phoenix in summer. The KEY WORDS IS SHORT AND TRIP.)

The tripped circuit breaker is incidental. (WRONG, especially if you are trying to open a b-lead OV relay.) You could just as easily use some sort of current limiting device, I suppose, if you really wanted to (this would probably introduce other headaches). The main action of the crowbar is to remove the field. (no, no, no, no, no, no, the field gets it power THRU the VR which is powered by SHIPS power in the case of an external VR. The crow bar will short out and melt unless the CB pops. In fact the crow bar will only "CLAMP" down for a few seconds before it melts without a heat sink. It is good for 10 amps continuous but the amps go to 100 or more for a nanosecond. Yes the grounding will LOAD down the alternator, but not until you remove POWER from the FIELD thru the VR will the electromagnet marvel called an alterantor stop making electrons.)

Common approach? no it is not. Its an awful approach and one man's idea with a big soap box, Bob Nuckolls, Aeroelectric Connection. He pushes this at his seminar and in his book. The modern way is with stabilized voltage reference electronics that OPENS or removes power electronically (solid state). The crude crow bar (that Bob sells $35), which causes a SHORT CIRCUIT to ground, which POPS a circuit breaker. His device is also solid state but its too simple. Van's aircraft expressly advise against using it with the 60 amp alternator and it voids the warranty. Why? because if the "crow bar" gets thrown into the monkey works, while the alternator is working, it will most likely damage it. It's like driving down the freeway and throwing your car in reverse. As well the alternators technical paper expressly forbids operation of the alternator while disconnected from the battery. The CROW BAR disconnects the battery and alternator. That's fine if the alterantor is dead but often the Bob N's crow bar sees a transient and BLOWS or shorts at bad times. He will say its the best thing ever and all who disagree are retarded, but I know better and so does Van.

The crow bar is better with externally regulated alternators only, like Van's 35 amp job. This way the crow bar only acts on the voltage regulator, which is fairly safe. If you must use some kind of OV device on your externally regulated alternator consider this device: http://www.periheliondesign.com/lovm.htm (NOTICE: This OV device does NOT short or pop any CB, it just removes power to the VR and thus the field.)


Bob N's idea comes from main frame computer industry I think the 1970's. It is a Rube Goldberg device, one thing leads into another. The "crow bar" if anyone does not know what we are talking about is a small electronic device that senses voltage. When the device sees an overvoltage it "throws" an electronic switch (SCR) and grounds or SHORTS-OUT what ever it is attached to, in this case a CB. The TERM crow bar comes from when they actually threw a big metal CROW BAR into a device to stop it or short it out. Ouch! His device is subject to nuisance trips because the voltage reference is not stabilized. It works but is subject to transient trips. This method requires the "crow bar" and circuit breaker. When attached to an internally regulated alternator you must add a BIG master relay sized continuous duty relay in the B-lead circuit. WHEN the crow bar grounds (SHORTS OUT) the circuit breaker it POPS and removes power to the B-lead relay, which opens. Mr. Rube Goldberg would be proud.


The Plane Power is 1000's of light years better. It just opens and its right on the alternator and there is not big heavy relays.

I am not saying Bob's crow bar doesn't work, but it tends to be worse than the cure. Bob makes up stories about the wide spread OV problem? Back in the days when they had mechanical voltage regulators OV was common. However how many cars made since the 80's have you had or seen get an overvoltage? NONE? It does happen but tends to be a minor 16 volt deal not a 100 volt nuke bomb Bob scares people with. He has stories but no facts to back it up. In a word its a rare event and not very serious. Besides if you lower engine RPM and add load, it will alleviate the OV. My point is if you can't trust the crow bar and it may do more harm than good, leave it OFF. Now if you are IFR, electrically dependant engine, all glass, by all means by a Plane power unit with a secondary overvoltage device.

When the crow bar trips with an internally regulated alternator the B-lead relay will try to open under load. It's like cutting or gnawing off your own leg to get out from a rock that rolled onto your foot. It works but its going to be a bloody mess. If you MUST have an add on secondary OV protection device to a I-VR alternator, please consider something else like this:
http://www.periheliondesign.com/lovm.htm You will still have to use a gosh awful BIG master relay type contactor on the b-lead. The way Plane power does it is elegant. You get what you pay for.

For those with just a 60 amp alternator I suggest you do NOTHING but fly and have fun. Don't add the crow bar, it will add weight, cost, complexity and increase the chance of a failure. The chance of an OV with a stock alternator installed just like it would be in a car is small to none. The good nippondenso I-VR (not cheap aftermarket regulators) will control and protect you all day, every day with IC chip or microprocessor. Would you put a CROW BAR into you PC computer. There are better ways (Sorry Bob Nuckolls and Rube Goldberg). Times have changed. It would take a very rare failure of the 60 amp alternator to ruin your day and where a crow bar would make any difference. Most of the time the alternator just dies, they don't OV. I would suggest a pull-able CB on the B-lead so if the alternator voltage starts to get wacky you have the option to manually pull the CB and isolate the alternator.

Sincerely Mr Rube Goldberg

[jcoloccia]

Uhm....I'm not even sure where to start so I'll just keep it simple.

1) The crowbar is on the FIELD, not the B-Lead

2) IF the Field circuit breaker never pops (i.e. the current never gets high enough to trip it....doubtful since it's shorted to ground, but irrelevant for this discussion), the crowbar still works PRECISELY as planned. Shorting the field to ground completely removes the field as quickly as possible. The crowbar works because it's FAST. It's FAST precisely because it shorts to ground.

3) Once again, the breaker popping is incidental. If you want to wire your plane with bus bar and heat sinks that can take the full output of the battery, you can leave the breaker out, or size it so it won't trip, and the crowbar still works. Of course, you'd drain your battery so that would be stupid. Remember, it works because you're SHORTING TO GROUND. The breaker popping is ONLY there to protect the wires (as it should be). If you prefer, lets stop saying "shorting to ground" as this seems to conjour up negative images. Instead, let's call it "grounding the field', just like we "ground the mag" (which no one seems to have any problem with).

4) Nuckolls did NOT invent the crowbar anymore than Apple invented Point and Click, Ford invented wheels or Boeing invented the airliner. It's a common technique when you have to immediately remove power from somewhere. It's common in power supplies. Your computer power supply probably has a crowbar in it.

5) It's pretty trivial to whip up a device that merely opens the field instead of shorting to ground...uh... "grounding the field". The reason the crowbar doesn't do this isn't because we "old fashioned" engineers are brain dead and can't collectively figure how to do it otherwise. Once again, it is intentional to COMPLETELY AND QUICKLY remove the field and drain off any residual as quickly as possible. Simply opening the field does not do this especially since the field is really powering a coil of wire that has lots of inductance.

6) Yes, using a crowbar to remove power to both the regulator and an alternator contactor for an internally regulated alternator is a bit messy. It would be just as messy to do it with perihillion's gadget. The messy part comes from killing the contactor in addition to the regulator. If you choose to only kill the regulator, the two designs are equivalent and it's merely a choice between popping a breaker or turning on a little light. I you want to also kill the contactor, then it's messy and inelegant for BOTH. It has nothing at all to do with using a crowbar or other kind of switch. That's irrelavant. Some feel that just removing power from the regulator is not enough because it doesn't nescessarily remove the field in an IR alternator. I'm agnostic on the issue, to be honest.

7) Perihillion's would probably work just as well as long as they actually ground the field when they trip (just based off what I read on the website). Then again it's likely more fragile. Big deal? No. Does it mean a crowbar's bad? Heck no. I can't say this enough...crowbars are accepted practice when you want to remove power NOW. I'm not trying to push one solution or another. I'm just trying to clean up this misconception that's been floating around that crowbars are somehow bad or "contraptions".

There are many ways to skin a cat. As soon as you choose IR alternator and decide you're killing a contactor as well as the regulator, you're made a mess no matter how you do it or who's product you use, OK? Anyhow, I'm not trying to stir the pot here. I'm just stating facts as I see them based on my own education and experience. Anyone's free to dispute them and we'll just agree to disagree (or you can change my mind...)

[gmcjetpilot]

Originally Posted by jcoloccia

Uhm....I'm not even sure where to start so I'll just keep it simple.

1) The crowbar is on the FIELD, not the B-Lead (Alternator with an internal voltage regulator (I-VR) don't have a field wire, so this discussion is about E-VR alts only.)

2) IF the Field circuit breaker never pops (i.e. the current never gets high enough to trip it....doubtful since it's shorted to ground, but irrelevant for this discussion), the crowbar still works PRECISELY as planned. Shorting the field to ground completely removes the field as quickly as possible. The crowbar works because it's FAST. It's FAST precisely because it shorts to ground. You have wired the crow bar improperly if you connected it directly to the "F" wire. This is NOT aeroelect connections schematics. The CROW BAR is designed to short a CB NOT the field directly. I strongly suggest you get other opinions if you don't believe me, but its your plane. If I understand, and I do, you will just make smoke. The crow bar should be on the BUS voltage NOT the field wire, which is not buss voltage.
click:
[img=http://img262.imageshack.us/img262/6117/presentation1gk5.th.jpg]

I penciled in what I think you have, a dead short to Field to Gnd thru the Crow Bar! Ouch, one of a few things will happen, you will burn one or more of the following: crow bar, wires, alternator, voltage regulator or nothing will happen. The CB IS PART OF THE CROW BAR AND YOU HAVE KIND OF BYPASSED ANY WIRE PROTECTION! You will still have a BATTERY. The battery will still try to pump juice thru the CB, the VR and down the field wire. You may, pop the CB but you may do some other nasty things. WHY WOULD YOU NOT WANT TO SHORT THE CB, TRIP IT AND REMOVE THE POWER TO THE FIELD????


3) Once again, the breaker popping is incidental. If you want to wire your plane with bus bar and heat sinks that can take the full output of the battery, you can leave the breaker out, or size it so it won't trip, and the crowbar still works.

I hope you are right. I would bet a 6-pack you make smoke and nothing happens, except damaged wiring or VR or alternator.


4) Nuckolls did NOT invent the crowbar anymore than Apple invented Point and Click, Ford invented wheels or Boeing invented the airliner. It's a common technique when you have to immediately remove power from somewhere. It's common in power supplies. Your computer power supply probably has a crowbar in it.

I know that, as I stated previously Bob did not discover electricity, but A KEY COMPONENT if the Crow bar is the fuse or CB which it works in concert. You have isolated the crow bar to a direct ground with a VR between it and the wiring protection?


5) It's pretty trivial to whip up a device that merely opens the field instead of shorting to ground...uh... "grounding the field". The reason the crowbar doesn't do this isn't because we "old fashioned" engineers are brain dead and can't collectively figure how to do it otherwise.

I can't disagree with brain dead part and clearly you are a man on a mission, but your wiring architecture is non standard as they say. Have you tested this theory?


6) Yes, using a crowbar to remove power to both the regulator and an alternator contactor for an internally regulated alternator is a bit messy. It would be just as messy to do it with perihillion's gadget. (Agree that is why I-VR alts should not have a crow bars and they don't need it.) Some feel that just removing power from the regulator is not enough because it doesn't necessarily remove the field in an IR alternator. I'm agnostic on the issue, to be honest.

I agree with all but the LAST paragraph if we are back to E-VR's. If there is NO power to the field it will collapse within milli seconds. Yes the CB takes time to trip. If you have an externally regulated alterantor, try turning the ALT off while it is running. What happens? It shuts down. Nuff said? (Note don't do this with I-VR alternators like Vans 60 amp, it is IC chip controlled and does not like being turned on while the alternator is spinning under load.)

Little definition, "FIELD" means magnetic FIELD of the rotor that is spinning in the Stator coil winding. If there is no power to the rotor (field) it collapses the field and the alternator can't produce power. End of story. I agree shorting the field may produce the same effect, but you still have a battery and hot wires if the CB does not trip. You may damage the alternators, VR and wires.

7) Perihillion's would probably work just as well as long as they actually ground the field when they trip (just based off what I read on the website). (NO that is NOT what the web site says, it is designed for 10 amps flow thru and to act as a OFF switch to power NOT a crow bar.) Then again it's likely more fragile. (how do you know that?) I'm not trying to push one solution or another. I'm just trying to clean up this misconception that's been floating around that crowbars are somehow bad or "contraptions".

One thing is your crow bar on the "F" wire is NOT seeing buss voltage. What voltage is it seeing? You don't know. Unless you test this rig, with your alternator and VR you really don't know what's happening. Even Bob's layout is semi flaky and finicky as is connected direct to the CB. Lets say for what ever the reason the VR goes wide open (unlikely, rare but could happen), the Crow bar clamps to ground, my guess is some "wire" will burn out in 1-2 seconds. The amps in the crow bar will be in the 1000's, but not for long. Than the OV will continue and/or you will have a fire. You may trip the CB and the OV will stop, if you are lucky, but you don't know until you test this SYSTEM. Bob's circuit is simpler and does not rely on the alternator or VR to act in a certain way. If the CB does not trip something must burn out. The solid state relay (SCR) is only good for a finite amount of current/amps/time.

There are many ways to skin a cat. As soon as you choose IR alternator and decide you're killing a contactor as well as the regulator, you're made a mess no matter how you do it or who's product you use, OK? Anyhow, I'm not trying to stir the pot here. I'm just stating facts as I see them based on my own education and experience. Anyone's free to dispute them and we'll just agree to disagree (or you can change my mind...)

You are stuck on GROUND THE FIELD. I can't stop you or do I want to, but I do think in my opinion you are fooling yourself.

It is a good discussion and appreciate your tenacity. You clearly thought it out, but I strongly disagree.

As far as I-VR, they are safe with out ANY crow bar. Crow bars stem from OLD electical systems from 1940's thru 70's planes. The modern I-VR alternator (in cars not planes) have a microprocessor control in a IC chip. There's a semi "fail safe" internal voltage control with modern ND alternators. Why would anyone use a dumb VR with out a brain? Simple consumer device has a microprocessor. Chance of OV is small. Heck w/ one engine, one prop, the prop can fall off. So you should only fly twins? Heck a wing on a RV fell off once, so we should strut the wing with some Cessna wing struts? Some times you got to take a chance on life. The Hodge podge add on crow bars for I-VR's is a Rube Goldberg.

NOW if you have an E-VR alternator as you apperintly do and decide to use a $10 1970's solid state Ford VR, than by all means put a Crow bar on it. We just disagree on how to wire it into the aircraft. However for 1/4 th the PRICE of a $230 B&C voltage regulator (which has no microprocessor, just a 1970's Ford regulator with a crow bar) you can get a solid state VR with internal OV protection. Yes the modern E-VR works by OPENING or removing power and NOT grounding or tripping a CB like the B&C does.

Good Luck.

[jcoloccia]

Hey look, my apologies. I don't mean for this to get out of hand. Notice on your diagram where the OVM hooks into the switch. The left side goes to the field breaker. Attached to the same point is the wire for the field. When you ground that point (#4 on the switch) it is both the field and the breaker...it's the same circuit. That's all The breaker popping doesn't kill the field. The crowbar kills the field. Eventually, the breaker pops and saves the wires.

I hate to drag this out but this is correct. I'm not saying it's the best/cheapest/most reliable/lightest etc way to go. I'm merely describing how a crowbar is designed to work.

I also agree with 99% of what you say about internal regulators. Not sure why you insist on assuming I'm talking IR when I'm talking ER and ER when I'm talking IR but in general we agree with IR ops and that it's probably silly to be opening alternator contactors. So we don't have to agree, and no one else cares, but we do happen to agree here

Whatever each of us decides, it'll still be probably be way more reliable than any of the planes I'm currently flying if the last 2 years are any indication

[gmcjetpilot]

Originally Posted by jcoloccia

Hey look, my apologies. I don't mean for this to get out of hand. Notice on your diagram where the OVM hooks into the switch. The left side goes to the field breaker. Attached to the same point is the wire for the field. When you ground that point (#4 on the switch) it is both the field and the breaker...it's the same circuit. That's all The breaker popping doesn't kill the field. The crowbar kills the field. Eventually, the breaker pops and saves the wires.

I hate to drag this out but this is correct. I'm not saying it's the best/cheapest/most reliable/lightest etc way to go. I'm merely describing how a crowbar is designed to work.

I also agree with 99% of what you say about internal regulators. Not sure why you insist on assuming I'm talking IR when I'm talking ER and ER when I'm talking IR but in general we agree with IR ops and that it's probably silly to be opening alternator contactors. So we don't have to agree, and no one else cares, but we do happen to agree here

Whatever each of us decides, it'll still be probably be way more reliable than any of the planes I'm currently flying if the last 2 years are any indication

Cheers, mate. As far a I-VR you do mention them a few times out right.**


I don't understand your statement?

"Attached to the same point is the wire for the field."

Do you or don't you have a externally regulated (E-VR) alternator? I assume yes.**

Did you or did you not wire the OVM to the master switch, as shown below on the left, or did you wire the OVM to the field wire on the "F" output from the VR?



So per the diagram above OVM on left (correct), the one on the right (not correct). DO you agree? I feel strongly about this.

It does not matter to me if you think the chicken or egg came first (OVM shorts the field first or the CB trips first), that's moot. However the OVM connected to the field is just a odd thing to do. Again if not fully tested integrated in your aircraft (which is hard to do), you may have smoke or fire or nothing during a overvoltage event.

Your two year experience, with all respect, really does not mean anything unless you had an OV and the OVM came to the rescue. I suspect you will fly the rest of you life with the crow bar going along for the ride, doing nothing. Its like a toilet paper bullet proof vest, its great if you don't get shot.

CROW BAR DESIGN: If you know electronics and it sounds like you do, you know Bob N's crow bar is a very simple device with a diode voltage / resistor voltage divider for a voltage refrence. This is 1950's technology. It is small and cheap, so he can sell $4 of parts for $35. The crow bar needs a somewhat stable voltage supply to measure and to work well. The "F" wire has large variations in voltage. Voltage in the "F" wire is not the voltage on the output (b-lead) or battery bus!!!! Your radios are connected to the battery buss not the "F" wire. The "F" wire can be at all kinds of voltages while the buss voltage remains stable. Your AVIONICS and EFIS are connected to the battery bus or B-lead side of the alternator not the "F" wire. You don't care what the voltage is in the "F" wire as LONG as you have the 14.3 volts or what ever on the Buss. The OVM should be on the BUSS!

IF YOU LOOK at Bobs Crow bar it uses 20 awg gage wire and a 25amp/400 volt SRC (part S4025L). This device will only take a DEAD short for a second. If you don't have a circuit BREAKER or FUSE open the crow bar power, the OVM wires may glow RED and SMOKE. I know, I'v seen these things burned into little crispy critters.

Let's say you did wire the CROW BAR or OVM to the "F" wire you should have a much heavier duty device than what B&C sells over the counter. To be clear however dead shorting the "F" wire is not good, I'm still not sure what you have without a wire diagram.

Any way it was a pleasure and hope it works for you, but you may never know? I would suggest you ask Bob N. Although we don't see eye to eye, he can explain this better and may have more salient reasons to wire the crow bar as shown on the left and not the one under the red circle and diagonal line. If you wire the crow bar to the POWER side of the VR and the CB you will have better and KNOWN results. Those knows are even a little flaky but the other way is a real unknown.

If you want to chat more or chat off line email me: gmcjetpilot@yahoo.com, other wise I hope you never have an OV. Take care.


**With an I-VR there is no field wire exposed. The IGN wire is a sleep or wake-up wire. It has nothing to do with the "field" or entirely with VR power, since the VR gets power internally thru the B-lead. IGN lead just keeps the VR from draining the battery (50 ma trickle) when you park and tells it to wake up and be ready to work when you get ready to start your car, that is all. E-VR and I-VR alternators are wired and operated differently. They are completely different animals and often are confused, mixed and matched. The principals of electromagnetism are the same but I-VR have a solid state chip that controls the alternator and does not need pilot intervention. They where made for a car, so they automatically come on when you start or stop the engine, ie spinning the Alt pulley. Have you seen a car with an ALT switch?