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Alternator Failure

mv031161

mv031161

Well Known Member
This is what happens to your brand new Oddissey Battery when your Suzuki Samurai Alternator Internal Voltage regulator fails and it ouputs 18 volts! I will reccomend a B&C Voltage Regulator to the RV8 Owner next!

 
From what I've gathered from aero electric, a crowbar over voltage module would have saved your battery
 
The B&C voltage regulator referred to in the original post has built in over voltage protection, which I believe is the point being made there.
erich
 
over voltage protection

Does anyone know of a supplier for a "free Standing" 14 v system over voltage protection module aside from the built in models usually included with the Alt or external regulator?
 
How does that wire in ? Has some pretty small looking wires on it. The wiring diagram did not open up on the B&C site.
 
DennisRhodes said:
How does that wire in ? Has some pretty small looking wires on it. The wiring diagram did not open up on the B&C site.
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Dennis, this module will protect an externally regulated alternator. It is connected to the field wire between the circuit breaker and regulator. When it senses high voltage it shorts the field circuit to ground which pops the breaker taking the alternator off line. This happens in milliseconds.

There is a way to use the module with an internally regulated alternator but it requires additional components. Details are in Bob Nuckoll's book, The AeroElectric Connection.
 
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Or an overvoltage annunciator. Second most critical to a low oil pressure annunciator. Looks like that battery cooked for a long time.
 
Low Pass said:
Or an overvoltage annunciator. Second most critical to a low oil pressure annunciator. Looks like that battery cooked for a long time.
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Overvoltage events, though rare, can happen almost instantaneuously. You would not be able to manually shut your alternator down in time to save your avionics in such cases. You need automated overvoltage protection to save the day.
 
I tried a cool little permanent magnet alternator from a John Deere garden tractor, but the high RPM caused by the Lycoming pulley size caused an over voltage condition before I ever flew it. I noticed the regulator driven idiot light flashing during Static RPM testing, and the volt meter just starting to break out of the 14.4 previous volts.
Now I have a DENSO Mini 2 ear alternator. It's a sweet little one wire unit with internal regulator. I'm sure these are very popular with the RV crowd, as they are light and put out a generous current. They are also very inexpensive.
What they don't have is overvoltage protection.
Lynn French (comments by 'Lectric Bob) went thru the bother to open a DENSO up, and add external regulation and posted the results online:
http://www.aeroelectric.com/articles/Alternators/One-Wire_Alternator_Conversion.pdf
I would be interested in retaining the internal regulation and simply adding the field shutdown circuit. Does anyone recall a DIY post on this? Or have anything to add?
 
erich weaver said:
Overvoltage events, though rare, can happen almost instantaneuously. You would not be able to manually shut your alternator down in time to save your avionics in such cases. You need automated overvoltage protection to save the day.
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Didn't say over voltage devices weren't good. But an alarm (if noticed) would have allowed him to protect the battery because this event occurred over many minutes.

But further, what avionics would be harmed by 15, 20 volts? My Dynon info says it's good from 12-30 volts, King radio, xpdr - 12-24. Garmin G3X, 10-32 vdc. (These are the specs, didn't say I would try it! )

I did have an over voltage condition some 12, 13 yrs ago. I lost a couple of LED elements on my trim pos indicator (nothing else). No annunciator or protective devices. I spotted the volt meter at 17, 18 volts and shut off the alt field.
 
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I don't consider myself an expert in such matters, but to my knowledge, over voltage events are not limited to the 15-30 volt range.
Erich
 
Perehelion Design

DennisRhodes said:
Does anyone know of a supplier for a "free Standing" 14 v system over voltage protection module aside from the built in models usually included with the Alt or external regulator?
Click to expand...

I would recommend this one:

http://www.periheliondesign.com/lovm.htm

It has a trip level of 16.2 volts. It is not a "crowbar", which forces a circuit breaker pop or fuse blow, but a device which senses the overvoltage and then interrupts the field supply gracefully.

Don
 
Be aware the common Plane Power alternator has a crowbar built into its internal regulator.
 
Not to highjack the thread, but if you install a B&C regulator (which has an O/V protection) take care to cover it in a way so no water could enter in it. I experienced a recurrent electric system fail, included continuous alternator field braker trip which almost made me abort a travel in Greece, untill I discovered it was dued to water inside the regulator. Regulator is installed in the upper portion of the firewall (engine side) and of course is covered by the cowl. However, I suspect that when parked outside during rain, water enters between the cowl and the upper fuse skin and then in the regulator. See my RV9 site, FLIGHT! page for details.
Camillo
 
Camillo said:
Not to highjack the thread, but if you install a B&C regulator (which has an O/V protection) take care to cover it in a way so no water could enter in it. I experienced a recurrent electric system fail, included continuous alternator field braker trip which almost made me abort a travel in Greece, untill I discovered it was dued to water inside the regulator. Regulator is installed in the upper portion of the firewall (engine side) and of course is covered by the cowl. However, I suspect that when parked outside during rain, water enters between the cowl and the upper fuse skin and then in the regulator. See my RV9 site, FLIGHT! page for details.
Camillo
Click to expand...

Perhaps the B&C regulator manual has been updated since you purchased yours. It now contains this rather stern warning: "NOTE - take care to choose a mounting location that will protect the LR3C from heat, vibration, and water".

Additionally, mounting on the cabin side of the firewall is encouraged in the manual.
 
The OV protection is certanily a plus in those Alt like Plane Power and B&C which provide that protection. Appears that externally regulated alts may be easier to "add" that on. Looks like the site in post from Don might be an option but also needs a contactor, 5amp supply and some wire. would be nice to see that device incorporate the "contactor" and feed the B+ directly. That should be doable with today's electronics.
 
B+ not just Field.

The OV failure mode in internally regulated auto alternators can be "self exciting" which, despite what you think, means that disconnecting the field isn't enough, you have to disconnect the current feed from the alternator(B+) also. So if you're using an internally regulated auto alternator(al la Vans standard) the OVP protection should include running the B+ through a contactor, the contactor should be powered by the field lead.

When the OV event happens, the crowbar pops the field breaker, the B+ contactor opens and the faulty alternator is completely isolated.

See page 2 here:
http://www.aeroelectric.com/DIY/DIY_Crowbar_OVP_F.pdf
Along with the warning not to use internally regulated alternators...

Electronics don't like heat... if you put the regulator behind the firewall you get to run 1000+ hrs with no alternator failures like me... I went through 2 automotive alternators in less than 100 hrs before I bucked up and got a B&C alternator...

Bill Judge
N84WJ, RV-8, 1100 hrs
RV-8.blogspot.com
 
The bulged Odyssey battery failed over time. It controlled the alternator's over voltage condition until it was over charged to the point it built up excess pressure and heat.
All the while, it was holding the system voltage down. I don't know how high the voltage initially went, but probably not enough to ruin modern dual voltage avionics.
Install a properly sized circuit breaker that can be manually opened on the alternator output wire. It would trip if the alternator 'went wild'. also, adding an over voltage alarm would inform the operator to manually open the circuit breaker.
Additionally, if you needed a bit more electricity to make it to the closest runway, the operator might briefly close the breaker to jolt some juice into the battery, then re-open the breaker?
 
Battery fAiled

The reason that battery looks that way: Ironically the battery sarted failing as we were approaching a paper pulp plant and a water plant which smells as bad as sulfuric acid! The sulfuric smell from the battery got worse and worse and we both thought it was the air outside! The EFIS never gave the PIC a warning and if it did, it got intepreted as something else. the engine parameter page was in minimized mode and the OV was not noted. See the trend here?

im glad we were close by our home airport. I was riding in the back close to the battery installation and my chest was on fire for a couple of days after! If that battery had caught on fire im sure there was nothing I could have done to extinguish it!

Few operational changes are in place now.
 
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