over voltage protection

Hello,

I don't want to start a IR/non IR alternator war here but I have a question.

I am going to be using the ND 55 (or at least it is the Van's 60 Amp model and it is already on order) and I don't want to use the over voltage protection. I don't think it is necessary and I can't figure out where to install another one of the huge contactors.

I am following the Z-11 system. I was wondering if I were to just by pass the part on the drawing for the over voltage and wire the 2-10 (dpdt) switch #4 contact directly to the F terminal on the Alternator and the wire from the # 2 terminal to the Battery contactor would that work?

I also am considering using a dpst 2-3 switch instead of the dpdt. Any comments?

Would installing the crow bar O.V. protect module after the 5 amp pull able fuse offer any advantages if I don't install the battery disconnect contactor?

Electro-confusion

Mike Ice
Electric's

Over load protection is very important. I had an "automotive" alternator fail and charged my system with 18+ volts. Cooked my EFIS stand by battery $30, and was suspect in weakening my BMA EFIS1 mother board ($900 a month later). A friend of mine had the same "auto" alternator, cost him $2,500 to fix a Dynon, radio, & transponder when his failed full power. We both replaced ours with an alternators from Plane Power.

Take a look at Plane Power. Over load protection built in, lite weight, and 2 year warranty from DATE of purchase.

http://www.plane-power.com/

BTW, Van's now recommends, & sells Plane Power alternators, this may be the alternator you have on the way?
__________________

over voltage

Geico266,

thanks for the reply. Your solution seems like a good one. But still not the answer to the questions I was asking.

If i can't figure this out I may just do as you suggest.

Mike

Mike, yes, you'd just go to the field contact on the alternator from that terminal on the switch, after passing through a 5A breaker, as shown on that drawing.

I agree with geico about plane power.. and I've got one as well. just might be a better choice in the long run.. hard to say for sure.

Living on the edge...

If you don't have the B-lead contactor, you don't need the OVP module - there is nothing it can disconnect that will turn off the alternator.

The 2-3 switch can be used instead of the 2-10 (even with OVP). The only 'disadvantage' is that you can't turn on ONLY the battery for testing, playing etc - the IR is powered up as well which is a additional drain on the battery.

I will join the choir and advise that OVP is cheap insurance - especially given the track record of the Vans alternators.

Relax don't worry

I agree an extra large contactor and crow bar is awful. Increases parts, weight and cost and can cause more problems than help.

Your chance you will have an OV condition, that will cause you grief, is a little more than your prop falling off, meaning forget about it. The level of fear and terror of OV is overblown and not substantiated with facts. There are stories and urban legend, but I have tracked the OV issue for a few years and they ARE either stories (myths) or where mild, most pilot induced.

Millions and millions of these alternators and ones like it, go 24/7, 365 days a year, in cars, trucks and industrial equip all over the world with out blowing up.

Keep in mind there are no new genuine ND's in this make model and all are rebuilds with after market parts or are completely new units made with all after market parts.

Most after market ND clones just fail or get a little flaky, where the voltage is unstable and goes above 14.5 volts but not cataclysmic. The highest I have head is about 16-18 volts. Most modern avionics can handle 30 volts forever and 60 volts for a short period. KEEP IN MIND, if you get a little high voltage issue you can lower the engine RPM a little and add load (all the lights). This will lower the planes voltage if the VR is not regulating properly.

Here is my suggestion (click to enlarge):


from Toyota (click me and watch me grow):
(ign switch is master switch with ALT/BAT)

PULLABLE CB
Look I suggest you use a pull-able CB in the panel for the B-lead. That way you can just pull the CB out if you want or need to isolate the alternator. I doubt there will ever be a NEED, but its a suggestion. If you stick with the FUSE under the cowl you still will be OK. The theory and legend of wild I-VR alternators is just not justified. My buddies buddies friends uncles said stories don't hack it.

THE BIG FUSE & NOISE
Bob and the "Z" dwg's call for a BIG fuse. Bob claims that you will (or might or could) get noise by running the B-lead to the CB on the panel. Not true/hog wash. The advantage of the fuse is one less wire penetration thru firewall and a foot or two less wire run. However if you put a CB on the far right of the panel and don't wrap it around every wire bundle in the plane it will be as quite wire this way as any. Bob is in the 1960's or 70's when alternators where noisy. Noise, audio in particular is from poor grounds not alternators with modern voltage regulators. Of course a device may put noise into the system but that has nothing to do with the B-lead and a CB in the panel.

REINVENT THE WHEEL
Having the B-lead CB on the panel is typical and in almost every Beech, Piper, Cessna, Grumman and you name it, wired w/ B-lead CB. The extensive use of fuses shot gunned around like automobiles do does save some cost. Not that there is any thing really wrong with it, but you should have ultimate control of the B-lead with a pull-able CB IMHO. Also the IGN wire to the alt can be controlled with a CB (pullable) as well. This allows THE USE OF a single toggle (DPST) and keeps you from being a switch monkey, turning the ALT on and off under load. Never turn your I-VR alternator ON / OFF while the engine is running. Just like all planes the ALT goes on before start, ALT off after you shut down with mixture. In a car where this alternator was designed to work THIS WAY; tied to the ignition switch, goes on before or with start and off after engine shut down. The voltage regulator will automatically take care of the alternator.

beginning to see the light

Thanks to all for your comments, please continue.

George I had your drawing all laid out and was about to start on it. One question. The boxes labeled M & S in the center stand for Master and Starter relay/contactor,solenoid don't they?

Also, if I follow that drawing would I take out the anl fuse called for and mounted down by the Master/Battery relays, in the Z-11 drawing?

I have never had a prop fly off. Saw one with a crack that had been stop drilled, part 135 operation, flying out of Fairbanks up and down the Yukon river hauling folks and mail.

I have never had a problem with over voltage in my cars or trucks either with an IR Alternator.

The Plane Power Alternator sure sounds better and better.

Mike Ice

gmcjetpilot said:

Your chance you will have an OV condition that will cause you grief is a little more than your prop falling off, meaning forget about it. The level of fear and terror of OV is overblown and not substantiated with facts. There are stories and urban legend, but I have tracked the OV issue for a few years and they either are stories (myths) or where mild, most pilot induced.

Click to expand...

Over voltage of the "unprotected" alternator cost me $1,000. A freind of mine just spent $2,500 repairing his "urban myth". Overblown? The extra money you spend on a OV protected alt is CHEAP insurance for your electrical system.

You state most electronics can handle 18 - 60 volts? Not the new experimental stuff guys are installing in homebuilts. Dynons, Blue Mountian, Garmin handhelds. While it might not kill these items, you still need to send them back to the factory or avionics shop for repairs. Blown internal fuses, cooked display screens, burned out / weakened Optima & Concord batteries. Big bucks and a long down times, both easily avoided with OV protection.

Not to mention the posibility of an in flight electrical fire.

If you would like to talk to the people involved in the incidents I mentioned so you can continue your "myth busting" PM me and I'll supply you with the names and cities they live in.

I'm not an electronics guy by any means. All I know is the bill, and down time I had to deal with when my alternator failed to full power. Never again for my ship.

JMHO & $.02 worth, do what you want.

gmcjetpilot said:

Your chance you will have an OV condition that will cause you grief is a little more than your prop falling off, meaning forget about it. The level of fear and terror of OV is overblown and not substantiated with facts. There are stories and urban legend, but I have tracked the OV issue for a few years and they either are stories (myths) or where mild, most pilot induced.

Millions and millions of these alternators and ones like it go 24/7, 365 days a year, in cars, trucks and industrial equip all over the world with out blowing up.

Click to expand...

George - I agree with you that OV events in cars are quite rare. I have also read a good number of reported OV events in RVs.

Is it possible that the difference in vibration between automobile and Lycoming could be the explanation for this difference in service history? Or, could it be due to the difference in typical density altitudes, which could affect alternator cooling? Or, maybe the alternator on Lycoming receives more heat from the engine than it would see in an automotive application.

Kevin Horton said:

George - I agree with you that OV events in cars are quite rare. I have also read a good number of reported OV events in RVs.

Is it possible that the difference in vibration between automobile and Lycoming could be the explanation for this difference in service history? Or, could it be due to the difference in typical density altitudes, which could affect alternator cooling? Or, maybe the alternator on Lycoming receives more heat from the engine than it would see in an automotive application.

Click to expand...

Not to mention the fact the car alternators we were installing are running backwards from their designed rotation on Lycomings. (The internal cooling fans are running backwards.) Humidity changes at altitude from ground level drastically effect carbon brush life, temp changes, vibration, all contribute to lower reliability and failures.

Do you use protection, over voltage

Thanks for the replies, but we are getting off track. I know all of the reasons folks don't or do what they feel is the best for their application concerning over voltage protection. And while I agree with you I also see where it might not be the best application for me. I just need some answers to a few specific questions.

Oh and Geico, yes, Birds do ice up, I saw some Ravens with icing the other day, 10 degrees and very foggy and they were all covered in frost, still flying though. The Ravens while iced up were not flying their usual frisky patterns, no rolls or loops, just straight and level.

George, I followed the plan you showed in that picture you posted and now I have another question. Should I take out that ANL fuse that the Z-11 drawing shows installing by the starter relay? Or should I just leave it there?

Once again thank you for you interest and advice.

Mike Ice

What does the Plane-Power OV device actually do when the voltage runs away? Does it trip the breaker? Oh, and also, can anybody tell me what type of alt mount a superior xp360 would have? Thanks.

Roger prop came off

Mike Ice said:

Thanks to all for your comments, please continue.

George I had your drawing all laid out and was about to start on it. One question. The boxes labeled M & S in the center stand for Master and Starter relay/contactor,solenoid don't they?

Also, if I follow that drawing would I take out the anl fuse called for and mounted down by the Master/Battery relays, in the Z-11 drawing?

I have never had a prop fly off. Saw one with a crack that had been stop drilled, part 135 operation, flying out of Fairbanks up and down the Yukon river hauling folks and mail.

I have never had a problem with over voltage in my cars or trucks either with an IR Alternator.

The Plane Power Alternator sure sounds better and better.

Mike Ice

Click to expand...

Ues master relay and starter relay/contactor. Prop came off, ouch! Yea I think the plane power units are nice. Talk to him and he has a nice product, good design and price is right.


Look if you want to use a CB in the panel, yea the way Bob has it is he goes from alternator (B-lead) to a fuse (ANL) and than the starter relay/contactor terminal on the master relay side (not starter side). It does not really matter where you attach the B-lead as long as it gets to the batter one way or another. The b-lead can go to the main buss, battery or between the master and starter relays. It's all the same.

If you want to keep the ANL fuse than keep it and just forget the CB. I like the CB in the panel for control, warm fuzzy. The BIG fuse under the cowl simplifies the wiring, is cheaper and easier to build and has almost the same level of safety and utility. So either way.

So is the ANL just a fuse?

I already purchased a 60 amp ANL which is called a "current limiter" in the B&C catalog. I plan to go with the Plane Power Alternator which calls for a Breaker/Fuse in the B lead. So is the ANL than the Fuse for the B lead?

anl current limiter

Rick,

The one I have sure looks a lot like a fuse. I bet it is just a different name. But a current limiter by defintion sure sounds like a fuse or circuit breaker.

By the way i am going to take mine out for now and use the B lead to a 60 amp CB (pull able) on the switch panel and not do the over voltage crow bar stuff. That gets rid of one more of those big honkin solenoid/contactor/relay gizmos. The 60 Amp alternator from Van's comes with internal over voltage protection (Voltage regulator).

Mike Ice

Thanks for the challenge but I do have some facts

Geico266 said:

Over voltage of the "unprotected" alternator cost me $1,000. A freind of mine just spent $2,500 repairing his "urban myth". Overblown? The extra money you spend on a OV protected alt is CHEAP insurance for your electrical system.

Click to expand...

YOU LEFT OUT ALL THE DETAILS. I bet it was a external voltage regulator? That's the problem with the rumors. Are you talking ND alternator? What vintage of radios died? What was damaged? This is good info, so please tell all of us more. Keep in mind this is all about internally Regulated Alternators I-VR, ND's specifically.

Geico266 said:

You state most electronics can handle 18 - 60 volts? Not the new experimental stuff guys are installing in homebuilts. Dynons, Blue Mountain, Garmin handhelds.

Click to expand...

That is not true

I called Dynon, their voltage range is as I said 10-30 volts and 60 volts peak. Also I asked Dynon if you had a super nova OV, what would be damaged and what would the cost of repair be? They said the repair would be small, because there is protection to the main circuits!

Garmin, they are made to 1-30 volts, I am reading the manual right now, for a HANDHELD Garmin 195. Operating voltage 10-30 volts. Surge? If its has a regulated power supply it probably can take spikes.

Blue Mountain? I don't know but if they don't have a regulated power supply I would be surprised. If they did not work with a wide voltage range and surge protected I would not buy it frankly.

YOU BRING UP A GOOD POINT. Not all radios are made to this 10-32 volt / 60 volt surge standard. Old radios most likely to not have OV protection, but some new ones don't.

My ICOM A200 com radio is NOT protected. The max for the ICOM is 16 v (according to the manual). I called ICOM and ASKED WHY? They said that is the way it is. I could put a "Transorb" on the CB to protect just the ICOM?

My OLD Collins TDR950 transponder is not protected for 30 volts. I called Collins (now S-tec, a Miggitt co). They don't make TDR950s any more, but I asked a technical guy what damage these transponders get. He said an OV can cause damage but it's usually limited to a few semiconductors on the board.

I would say if YOU did have $100,000 worth of avionics made to 1970's standards I would be more worried about OV.

Geico266 said:

While it might not kill these items, you still need to send them back to the factory or avionics shop for repairs. Blown internal fuses, cooked display screens, burned out / weakened Optima & Concord batteries. Big bucks and a long down times, both easily avoided with OV protection.

Click to expand...

I can't say what happened to you, but guess it was with a Cessna, Piper or Beech and not a ND alternator and modern avionics? You are right OV is NOT good. If your radios or GLASS burn up at 16 or even 18 volts, it's not aerospace quality, at least by today's standards.

Geico266 said:

Not to mention the possibility of an in flight electrical fire.

Click to expand...

Sir I don't mean to be condescending, and I am not very diplomatic. You need to take a deep breath. I might say PROVE IT! What is going to catch on fire? What case have you seen where a ND I-VR caused a fire? There are fires and electrical ones but none involving ND alternators I know of.

I researched this on the "National Highway Traffic Safety Administration's" (NHTSA) data base. NHTSA's data base has ALL auto/truck consumer complaints, manufacturer's service bulletins, letters, trouble reports and recalls. I looked at ALL issues with electrical fires, alternator fires, alternator reliability and spacifically Nippon Denso. There where no alternator fires, induced fires or recalls with the ND brand. ND has no history of any problems in millions and millions of vehicles and decades of service.

There where electrical fires (Ford). There where alternator problems (Hitachi and Ford). The electrical fires associated with alternators usually was the result of something being close, touching the alternator and catching on fire. Faulty wiring or bad connector plugs where also a big problem.

High voltage will not melt the wire, power will. A short to ground on a hot wire will cause the amps to go to infinity. That is bad. The wiring on a 28 volt plane is the same, actually it can be smaller than a 14 volt plane.

The propaganda got out of hand for awhile on I-VR alternators. They are designed to work with OUT add-on OV garbage. The risk is small. The worst case scenario survivable. To avoid fire, keep things away from the alternator, wire it properly and make sure no oil is dripping on it. (no kidding)

Geico266 said:

If you would like to talk to the people involved in the incidents I mentioned so you can continue your "myth busting" PM me and I'll supply you with the names and cities they live in.

Click to expand...

By all means Sir, please lets get the facts out. Lets get the details, RV model, ND alternator model, what happened. Details, details, details, the devils in the details.

I can tell you about 5 cases in planes and 1 in a car where a ND went a little wacky with voltage. I first tell you about the worst two:


In the cases where the alternator was shut down with the ALT switch, I'd say don't always count on it. That is why I like the CB on the panel. The lesson is have a OV warning light and don't cycle the ALT switch with the engine running. The other cases of OV where mild and basically the voltage was not stable, going up/down with RPM and load, but max Volts where mild.

My RV4's ND had 1000 hours with no problems before I sold the plane. Another guy had the same experience, but the brushes went at 800 hours. It's still going strong. Both of my Acura's with lots of miles and years, both with ND's are still working great.

I've asked Nuckolls and others about their stories. Bob said some guy in a Lancair had $100,000 in damage with a ND alternator? I asked for details: data, time, place, equipment, narrative, analysis or ANY THING; I got nothing but "well I did not see it but I heard." I think it turned out to be a B&C alternator!

Geico266 said:

I'm not an electronics guy by any means. All I know is the bill, and down time I had to deal with when my alternator failed to full power. Never again for my ship.

Click to expand...

OV is COMMON! Happens! BUT...... with 1960's and 70's aircraft alternators and regulators, because those OLD externally regulated alternators are crude they need OV protection. Old planes used old autolite, prestolite, motorola, delco auto parts from 1960's Ford's, Chrysler's and Chevy's.

Geico266 said:

JMHO & $.02 worth, do what you want.

Click to expand...

I appreciate a challenge. Let me know what happened to you. If you want belt and suspenders on your ND alternator I suggest PLANE POWER.

How it really works, knowledge is power

Here is the thread I just posted ON how voltage regulators work, how alternators work. Knowledge is power.


http://www.vansairforce.com/community/showthread.php?t=14340

Still wondering what the Plane-Power OV does in the event of a runaway.

Interesting stuff. Another huge piece which always seems to be missing from the-sky-is-falling OV issue is the effect the battery has on a runaway alternator. Let's just assume the alternator tries to go ballistic. There is a battery in the circuit which doesn't really allow its voltage to get high without putting up resistance (pun intended). In other words, as the errant alternator tries to put out increasing voltage, the battery causes the current to go very high. If there is a circuit breaker on the line, it will trip and the alternator can go ahead and melt itself, but the aircraft circuitry is out of the loop. If someone has a high power, adjustable power supply, it would be interesting to hook it up to a battery like an Odyssee PC680, and see just what sort of current it would take to drive its voltage up to 18 volts, for example. I would suspect it would be waaaay above the 50 amp circuit breaker in my plane, for example. Cranking amperage of several hundred amps only reduces the voltage from 13 down to maybe 8. The same order of current would be needed to bring the battery voltage up by 5 volts as well. If one takes the stated internal resistance of the PC680, for example, and calculates the current necessary to drag it up to 18 volts, the current will be around 700 amps. My little 40 amp alternator running through a 50 amp CB will simply not drive the battery voltage up much no matter how hard it tries.

The important point one needs to keep in mind in these discussions is how pitifully weak the alternator is compared to the battery. The PC680 short circuit amperage is greater than 1800 amps!

I would submit, to much flaming I'm sure, that if the system voltage has gone up to damaging levels, something else is amiss in the wiring design or battery integrity.

Good Thinking Alex!

I must admit Alex, I had never thought of the battery doing that, but it sure makes a lot of sense to me!

And that is what is called "Systems Engineering"....looking at the entire system, and not just analyzing the individual components.

The Valkyrie has an external O/V protection on the SD-8 standby alternator, but relies on the Internal O/V protection of the ND alternator - and I'm comfortable with that.

Paul

But, if someone isn't willing to spend the time and money to put in OV protection, what are the odds they will spend the time and money to do battery capacity testing and/or replace batteries regularly? Any takers on this one? I think we have to assume that those batteries will remain installed until they will no longer reliably crank the engine.

Once that battery is a few years old, I wonder how its ability to hold down the voltage in an OV event is affected.

OV Protection

GMC et al:

Years ago I had a 72 Toyota Pick Up that had an alternator go bad. Replaced it with a rebuilt unit.

Miles from home of course, I smelled a strong odor of sulfuric acid. Pulled over, popped open the hood and the battery was literally boiling. Suspecting the rebuilt ND alternator, I disconnected the "B" lead and drove to the next town large enough to have a parts store and bought another rebuilt alternator.

Cured the problem. Have no idea what the voltage went to but there was no apparent damage to any of the electrical wiring or eqpt. It sure put out enough current to boil out a few ounces of electrolyte.

Of course it never got reported to the DOT

Mannan Thomason
RV-8 N161RL (No One Girl)

I had a similar episode that ended with the coil exploding and expelling its guts all over the engine compartment, which effectively killed the engine and solved the overcharging problem.

Kevin Horton said:

SNIP

Once that battery is a few years old, I wonder how its ability to hold down the voltage in an OV event is affected.

Click to expand...

It would be very interesting to do this testing. One would need one used battery and a big power supply. Perhaps the big power supply could be a couple of big 12 volters in series. Controlling and measuring the current would be the difficult part. Hmmmm, need to think about this.

Use a welder transformer and a BIG variac! Commercially-built rectifier bridges for several hundred amps are available relatively cheap.

gmcjetpilot,

Mick Ice asked about overload protection in this (his) thread. I have stated my opinion and experience in this matter. Not having OV protection cost me $1,000, and cost my friend $2,500. I stand by my statements as facts, not rumors. Both planes involved were RV-9A's.

Van's now recommends and sells Plane Power alternators with OV protection. If you want to disreguard what the manufacturer of the RV kits recommends do what you want. May I suggest you call Vans and quiery their electronics engineer why they recommend OV protection.

It is interesting, in your informative thread about alternators you do make a footnote worth repeating;

**(Why are Van's ND alternators unreliable? Well for one its a matter of poor aftermarket parts and rebuilds. OEM ND units where of a different and higher quality apparently. Unfortunately they stopped making the models we use 10-15 years ago, so aftermarket is all we have now that the salvage yard supply is dry. Not all aftermarket parts are bad, and they certainly are not all of the same quality. Van has a generous return policy, and they now have a better quality supplier I believe. Also the "Plane Power" brand of ND alternators is high quality, and they do add an OV module that cuts power to the alternator in the unlikely event of an OV, if that makes you more comfortable. The price is set right and they are nice.)

Enough said.

You build and fly your plane the way you want, and I'll do the same.

AlexPeterson said:

My little 40 amp alternator running through a 50 amp CB will simply not drive the battery voltage up much no matter how hard it tries.

I would submit, to much flaming I'm sure, that if the system voltage has gone up to damaging levels, something else is amiss in the wiring design or battery integrity.

Click to expand...

No flaming here, and you're right to some extent. The battery will absorb an awful lot in terms of short "spikes" and the like...it makes an awesome filter. A fully charged battey, though, is drawing very little current at the 14V (or whatever) we're holding the buss at. You can basically say that about any voltage you put on the buss. Once the battery's charged, and it'll charge at practically any voltage over 13.8, the current drops off sharply. It's quite difficult to increase the current just by craking the voltage, just like it's difficult to get any usable energy out of a practically discharged battery (although you may get a very brief, very large "short circuit" current for some very brief time).

So if you had a regulator/alternator failure that dumped the full bus voltage right onto the field, the battery would absorb some but I think you'd quickly have some excitment under the cowl. You're CB probably won't trip since your alternator probably can't put out enough sustained to trip it (just a guess) but your bus voltage could be significantly higher than 14V and your battery/avionics may be very sore when you land

I'm not saying any of this is likely but that is the rational behind OV protection.

I know precious little about electrons, but I have read a few books lately and I keep up on the list here as well. I'm confused. Somebody asks about how to correctly wire things without OV protection and George steps in to say that OV problems are mostly unsubstantiated myth anyway. Several folks chime in to give first hand accounts to the contrary. They are then given the third degree as if they are making this stuff up. Even a dope like me can get a few things out of this dialogue:

1. In theory, OV can occur.

2. According to eyewitness accounts, it has occurred in cars and planes.

3. An OV event can be expensive and possibly very dangerous.

szicree said:

I know precious little about electrons, but I have read a few books lately and I keep up on the list here as well. I'm confused. Somebody asks about how to correctly wire things without OV protection and George steps in to say that OV problems are mostly unsubstantiated myth anyway. Several folks chime in to give first hand accounts to the contrary. They are then given the third degree as if they are making this stuff up. Even a dope like me can get a few things out of this dialogue:

1. In theory, OV can occur.

2. According to eyewitness accounts, it has occurred in cars and planes.

3. An OV event can be expensive and possibly very dangerous.

Click to expand...

4. OV protection is a CHEAP insurance policy.

If your external VR is tied to your buss on the buss-side of an alternator breaker, when you open the circuit the VR will detect the decreased battery voltage and send max current to the alternator field. This will cause the alternator voltage to go out of sight! Then when you close through the alternator breaker, you put an incredible transient on your buss, which, depending on the wiring inductance from the buss to the battery, could cause a substantial voltage transient in your avionics. With the VR tied to the alternator-side of the alternator breaker, the VR will try to maintain regulated voltage.
I designed and built a VR with series OV protection with hysteresis. When the voltage goes above 14.5 volts, the series transistor in the field supply turns off. When the voltage goes below 10V it turns back on. If there is a failure in the regulator portion of the circuit, there will probaly be an ON-OFF oscillation, but at least the time-constants won't let the alternator put out damaging transients! I would guess that the voltage cycling up and down like that should get the pilot's attention! If not, a visual indicator could be tied to the hysteresis network to show the problem.
I did some investigation of alternator noise a few years back. That whine is due to a fly-back condition that exists when the ON diode in the rectifier turns off when its winding voltage falls below that of the next rectifier in the bridge. That diode's current suddenly tries to go to zero, which causes a transient oscillation whose frequency is determined by circuit capacitance and inductance. It's got lots of harmonics which can be both radiated and conducted!

over voltage over blown or not!

Folks,

Wow, who would have thought a couple of questions could lead to so much GOOD information.

It wasn't that I didn't want to take the time or spend the money to install OV protection on a perfectly good IR alternator, it was just that I made up my own mind that it wasn't necessary (for me).

Any how, moot point (for me) I called Van's to make sure my new alternater that is shipping this week is the Plane Power unit. Now I will have the belt and suspenders approach.

I still find all of this very interesting and now that I know just a tiny bit about electricity I am sure I can make some great mistakes.

Anyhow if anyone does any experiments and blows up a battery (on the ground in a controlled experiment) please share it with us.

Mike Ice
still wiring but soon will be working on the canopy.

Icom clarification

George mentions above that the Icom A200 has no overvoltage protection, but when mine inadvertently got too much voltage for breakfast one morning and quit working, I discovered there is an internal fuse (old style glass with metal ends) inside the radio. It saved my radio's bacon...

A little more information...

I spoke with a technical person at the factory that makes Odyssey batteries today. I asked him how much current he thought it would take to drive the voltage of a PC680, for example, up to 17 or 18 volts. He wasn't sure, but he didn't think it was anywhere near as much as I alluded to in an earlier post in this thread. In fact, he thought a fully charged battery wouldn't take much current with 17 or 18 volts applied.

I'm afraid we will have to do the test to really find out.

Good to know

Bob Brown said:

George mentions above that the Icom A200 has no overvoltage protection, but when mine inadvertently got too much voltage for breakfast one morning and quit working, I discovered there is an internal fuse (old style glass with metal ends) inside the radio. It saved my radio's bacon...

Click to expand...

Yes sir that is good to know. What I meant was the regulated / surge protected power supplies the new stuff has. That is good to know the fuse blew.

AlexPeterson said:

I spoke with a technical person at the factory that makes Odyssey batteries today. I asked him how much current he thought it would take to drive the voltage of a PC680, for example, up to 17 or 18 volts. He wasn't sure, but he didn't think it was anywhere near as much as I alluded to in an earlier post in this thread. In fact, he thought a fully charged battery wouldn't take much current with 17 or 18 volts applied.

I'm afraid we will have to do the test to really find out.

Click to expand...

There was the one Odyssey that puff out from extended over voltage. The technical manual say 15 volts max for charge. I am sure it can take short times with high volts. Even if its not drawing much current it is doing damage I guess? Needless to say its not a great thing but not a explosion.

Alternator wiring

Interesting thread as I logged in to ask a question about this very subject, if I understand the thread correctly the alternator I will get as part of the firewall forward kit will be a Plane Power with internal regulator and overvoltage protection is this correct?
As I am also using the Z-11 drawing I assume that I connect the alternator field connection directly to the Battery/Alt Master Switch and I now put a CB between the main power distribution bus and the Battery/Alt Master Switch? If this is correct what amperage would be required?
Thanks

No sorry, but its all good

uk_figs said:

Interesting thread as I logged in to ask a question about this very subject, if I understand the thread correctly the alternator I will get as part of the firewall forward kit will be a Plane Power with internal regulator and over voltage protection is this correct?

Click to expand...

No you get the plan vanilla Nippon Denso Clone with internal regulator. Does it say plane power and have a little external box hanging off the back? Good news, there is nothing wrong with a stock ND. 1000's fly, with 1000's of hours of reliable operation. You hear sales pitch with fear mongering, but ignore it. It's not based on facts. Your ND from Van's is fine.

uk_figs said:

The Z-11 drawing I assume that I connect the alternator field connection directly to the Battery/Alt Master Switch and I now put a CB between the main power distribution bus and the Battery/Alt Master Switch? If this is correct what amperage would be required?
Thanks

Click to expand...

Internal ND's do not have a FIELD wire. I am not being snarky, its very common misunderstanding and internally regulated (IR) and externally regulated (ER) are very different. They are installed and operated differently. I'm of the opinion that the Z drawings are not suited for IR alternators. Bob's (IR) alternators, his own words, is poor, but he has come a long way in the last year, but he still tries to fit EI alternators into his wiring like they are (ER) alternators.

See my post in this thread, there is a thumb nail sketch. It shows the wiring.
http://www.vansairforce.com/community/showpost.php?p=97985&postcount=6

The current draw on the IGN lead of a ND is milli-amps, not 5 or 7 amps as Bob thinks. Bob gets ER and IR mixed up, 1/2 or a 1 amp CB is plenty. Remember the IGN lead going to a ND is not a FIELD wire, its a LOGIC or SIGNAL WIRE. It tells the computer inside the alternator (yes the IR has a microprocessor) to come alive or go to sleep.

I can't say it enough NEVER turn the alternator ON or OFF while the engine is spinning.

The BIG disconnect (pun intended) between Bob's Z drawing is Bob loves a BIG fuse between the B-lead (output) of the alternator and battery. Bob loves to run that B-lead right to the battery with that big chassis fuse under the cowl. That's fine you can do that; that is what most cars do. This is the modification of above (click):


Bottom line follow the diagram posted for the IGN and L (light). The light is optional, but I'm a big fan of using it. Its an over-volt, low volt, lost belt, fault light. Install the alt Light at your option, if you have another low volt light. You should have a low volt light of some kind.

If you are going with a stock ND than go that way. You will be fine. Millions and millions of cars, trucks, industrial and farm vehicles going 24/7 world wide in extreme conditions can't be wrong. OV IS NOT A PROBLEM. Leave the OV relay for the ER-alternators, they do need it.

If you are really scared, may be you can return the unit you have or sell it and get a Plane Power unit. If you are flying IFR or have a electically depended engine that might be a reason. The Plane Power has consistent QC and the added on OV module is nice; it shuts the alternator down properly. It's totally different than the way Bob's OV relay crow bar works.


OVERVOLTAGE RELAY
MY opinion - Don't use the crow bar, OV relay, on a (IR) alternator out-put. Doing so will likely damage the alternator. Van agrees and will not warranty your alternator if you do this. Again (ER) verses (IR) are 180 degrees apart. The Nippondenso was designed to not need an OV relay. Disconnecting the alternator output from the battery, which is what the OV relay/crow bar does, while the alternator is powered, will damage any alternator. The technical data with any modern alternator says don't disconnect alternator from battery while its running. Why have something that can (will) damage a perfectly good alternator. The cure is worse than the ill.

uk_figs said:

...if I understand the thread correctly the alternator I will get as part of the firewall forward kit will be a Plane Power with internal regulator and overvoltage protection is this correct?...

Click to expand...

Dave: No, the FWF comes with the ND alt as pointed out by George however, Van's will be happy to delete the ND alternator and substitute the Plane Power for the difference in cost. I'm just a regular Joe but, I recommend the swap. The Plane Power has the correct fan rotation so they are actually moving cooling air through the unit plus it has positive overvoltage protection.

It's the only IR alternator that has Bob Nuckoll's approval (if that's important to you).

Are you buying the Van's wiring kit (in the FWF) or rolling your own?. Many builders who use the Z architectures delete the wiring kit from the FWF because it requires major modifications to use with a Z. It also comes with CBs which doesn't suit many Nuckollheads desiring fuses.

Jekyll

OV protection etc

Thanks for the responses, I will probably do the switch to the PP alternator version. I already purchased the Vans wiring kit seperately so will be deleting that from the FWF kit and I plan on using the CB switches instead of fuses except for the avionics bus relay which has fuses.
At this point I am trying to reconcile the Vans electrical schematic and the Z-11 schematic to my desired panel layout which is all electric and figure out the correct CB values, busses, number and type of switches etc so I can plan and start the installation layout.
As I am not an electrical engineer the alternator section is giving me a headache, I checked the Plane Power site and they have a drawing that shows a 60A CB on the B side and a 5A and 1A CB on the switch and warning light side, if the 60A CB is in the cockpit do I have to run a big as**d wire from the starter solenoid to the panel? Do I need this?
If there is problem with the alternator voltage in flight what is the correct approach to shut down the alternator.

You can put an ANL-60 on the fw versus the CB; check Dan Chekoway's site. Just need the 5 amp cb in the panel.

Jekyll