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

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.

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.

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.