Sign in to follow this  
Followers 0

582 charging


35 posts in this topic

Posted

Recently on startup I see my voltage go high for a while(16vat idle, off the guage at revs)

This is a randome and recent thing

About 150 hrs ago I replaced mi original regulator when in flight it went to full charge a cooked my battery.

I currently run a briggs& Stratton reg which looks the same but has a separate earth wire.

Question1

Where should I start looking?

Q2

If I were to run a circuit breaker,where should I put it

1

between the battery and regulator

2

On one or both yellow wires from the charge coil.

There appears to be a bit of conflicting information on the best method any advice preferably based on experience would be much appreciated

Share this post


Link to post
Share on other sites

Posted

I like the key west voltage regulator.  I am not an electrical guru, I will leave that to someone like ChrisB to hopefully answer.

 

:BC:

Share this post


Link to post
Share on other sites

Posted

I would order a key west reg. They run about $65. I ran a fuse between the reg and my power distribution bus.

Share this post


Link to post
Share on other sites

Posted

Key west has been on my challenger now for 325hrs never goes above 14.1 volts I would buy another one.

Share this post


Link to post
Share on other sites

Posted (edited)

What is the best overvoltage gizmo to use for a car-type, or airplane type, alternator that has a built-in regulator?

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted (edited)

You are talking to the guy who fried the alternator on the test stand at Av School !!!   :lol:

I wouldn't know a "Zenith Fryode" from a "Rectalfire", but I can machine most anything.

I have something in a package that Aeroelectrics ( Jim Weir, the guru who writes for the aviation mags and used to own Northern Lights Electronics ) sells.  I tried to download the instructions for it, but he has all his site files "Zipped" and I don't know how to unzip them!

But I see all kinds of overload protectors for Cessna, Piper, whatever, being sold on ebay....

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

I'm sure if you ever saw a rectalfire you would recognize it and be able to tell the difference... :handjob:

Share this post


Link to post
Share on other sites

Posted (edited)

I guess it just don't work to make funny statements when asking serious questions.

There are no serious answers!

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

What engine? Are we talking full on car / airplane type alternator or two stroke lighting coil? Most two stroke lighting coils have a hard time generating enough power to overvoltage anything. I am a fan of key west regulators for two stroke lighting coils. They are very nicely made and to my knowledge a pass regulator that doesn't need a load to regulate properly. However, the standard rotax shunt regulator works great too as long as there is a 1A or so load on it all the time, like position lights or something. If you are talking a full on alternator setup it is easy to understand how it could overvoltage if the field coil is fully energized by a failed regulator.

 

Chris

Share this post


Link to post
Share on other sites

Posted (edited)

Dusty was talking about overvoltage on 2-stroke, I think.

I was asking about overvoltage protector for big alternators on certified engines and car engines.

If my car doesn't have one, then why does my plane need one?  And, what kind is best?

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

Hi Ed,

Your car doesn't have overvoltage protection because the regulators built into automotive alternators are so reliable that failures are virtually unheard of.

 

Still, there is a lot of debate in some circles about the value of overvoltage protection in modern alternators used for experimental aircraft. Bottom line is there is usually a transistor in emitter follower configuration that regulates field current in most alternators. If this transistor fails (like I said, virtually unheard of) it would apply full field voltage to the alternator creating a serious runaway overvoltage condition that cannot be "turned off".

 

In a car or airplane it would be an expensive proposition to fix all of the electronics that will blow up. In an airplane of course the potential consequences are worse because you are in the air.

 

That said there are several approaches people take when using automotive internal regulator alternators in aircraft.

 

1) do nothing and run the automotive type alternator as is which is what I think most people do.

2) disable the internal regulator and install a custom aviation specific external regulator with circuitry that allows you to truly disconnect the field voltage with an ALT switch on the inst pannel.

3) Install a Zener crowbar type circuit that blows a breaker which in turn incorporates a relay to disconnect the runnaway alternator output from the electrical system.

 

Now what was it you were asking? :-)

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Oh...Certificated aircraft incorporate external regulators similar to #2 above, except the alternator and regulator are designed ground up specifically to be able to positively disconnect field voltage from the alternator.

Share this post


Link to post
Share on other sites

Posted

Ed

Trying to be helpful ^-^

I think automotive alternators have internal regulators and attendent overvoltage protection.

 

This link is to a external overvoltage protection device.

http://www.bandc.biz/over-voltageprotectionmodule.aspx

 

I muddled through an extensive old post discussion on the RVairforce about this same subject. Unless you are a EE you may have difficulty understanding it. I sure got lost...

Share this post


Link to post
Share on other sites

Posted

Yes automotive alternators with internal regulators do have overvoltage protection...built in. And it works perfectly almost all the time which is why they are so reliable. I mean have you ever even heard of a modern automotive alternator failing in a runnaway condition? I havent. The problem is that the internal regulator over-voltage protection scheme still relies on the transistor I described above to cut the field voltage. If that transistor fails in a short, the alternator will run away with no way to turn it off. That's the difference between a true aviation specific alternator which is POSITIVELY controlled by the pilot via a switch and an automotive alternator with internal regulator.

 

I worried about this on My Magnum which has a internally regulated automotive Nippon Denso alternator sold as an experimental aircraft alternator. I ended up putting a 40 amp button type circuit breaker (one of those you can pull to disconnect) in the pannel in easy reach. I figured if the alternator ran away, it might blow up some electronics in my plane (strobes, radio, transponder), but that i would figure out something was going wrong pretty quickly, look at the voltmeter and pull that breaker before more serious shit would happen like a fire or something. That was the compromise I struck with myself. Everyone has their own risk tolerance and what measures they want to incorporate to control risk. I figured in reality it was never going to fail, and if it did i could get it figured out quick enough so at most some electronics might get ruined, but that i would figure it out quickly enough to positively disconnect it from the system.

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I'm writing too much and saying contradictory things when I re-read what I wrote. First I said automotive alternators do not have overvoltage protection when in-fact they do. What they do not have is catastrophic regulator failure protection. For the point I was originally trying to make it doesn't make any difference, but when we really dive into the details I should have been more exact. I think I'll give it a break for a while! :-)

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

Chris,

     Thank you for all the writing and the most informative answers I have ever gotten.

Question:  I also have a 40 amp Nippon alternator internal regulator - what wire do I put the circuit breaker on?  Hot-Output wire?

I thought that once an alternator was energized, then until engine shutdown, it was self-energizing to the field :huh: unlike the old generators.

     Unfortunately, we have now lost track of Dusty's question of 16 volts (?) from his 2-banger thingy! 

Sorry Dusty, but this was the best chance for me to ask my question too.

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

Great discussion guys! Love this forum and our members taking the time to share knowledge.

Share this post


Link to post
Share on other sites

Posted (edited)

yes - Love the info - Now, got to get Dusty some useful info....for ALL the 2-strokers!

We got the Key West info - but no info on his overvoltage - unless it is just, not having the Key West?

EDMO

BTW:  I am parting out my 532 - If anyone needs starter / stator thingy, etc.  PM me.  Exhausts, Carbs, fuel pump, A-drive and adapter plate are already sold.  Still got the engine with thingys on it....Sold my boat, so don't need an anchor!  :lol:

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

Hey no problem,the topic went astray but I still found it interesting.

Looking at the key west option ,about four times the price of what I have.

One of our members fried his key west and charge coil ,he doesn't know which happened first.

A circuit breaker would be a good idea in any case ,but where is the safest place to put it?

Share this post


Link to post
Share on other sites

Posted

Dusty I've got a Rotax one I can send you if interested. It's used but works. Leni gave it to me I'd like to pass it forward if you can use it.

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

Dusty,

     Unless Chris says different, I can only guess that you put the circuit breaker between the output side and the busbar that feeds your battery and instruments - may not protect stator and regulator, but might save battery and not smoke something inside.  Then, look for a landing spot!

I've got analog v-meter and amp-meter, plus expensive aircraft LED digital voltmeter - also a LED digital voltmeter that plugs into cigarette lighter socket - that last one is advertised in Aviation parts on ebay for about $23, but if you go to Automotive LED voltmeters on ebay you can buy it for about  $3 or less - and it works in my truck.  I haven't compared the reading of all of them yet.  There is also a combination volt/amp LED meter, hard-wired, that don't cost much - haven't tried it.

EDMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

For Ed- If you do a switchable breaker like I did it goes on the big output wire of the alternator. It will allow you to manually disconnect the alternator from the system if it runs away, and will also protect the rest of the electrical system in the plane automatically if the alternator should fail in a total short circuit to ground as opposed to failing in a runaway mode.

 

For Dusty- Grab that free Rotax regulator and install it. Make sure you have a small load on the system like position lights so it will regulate properly. They are bombproof regulators. I would be super surprised if you ever see an overvoltage again. You do have a battery right? How big is it?

Share this post


Link to post
Share on other sites

Posted (edited)

Thanks Chris,

      Next Question - I am sure you have answers - Spruce lists breakers to 35 amp - then 50 to 100 amp - Where do I find a 40 amp pull-type breaker - How much is it ?

      I may have a 40 amp regular breaker in my Piper parts, and have the split Cessna master switch - Guess this wont work?  I could add a heavy toggle or pull switch to the 40 amp breaker circuit.

      I really APPRECIATE all the good info you have posted.

BTW: I have a $50 bid right now on a Nippon alternator - So will have one spare heavy Nippon alternator, and a lightweight spare if you ever need another, if I get the bid.

      There is another Nippon small alternator on ebay with a large 3 3/4" pulley - Do you think a larger pulley is needed with high rpm auto engines, or is the stock pulley OK?

I may also have a Rotax regulator if someone needs it - (little flat square thingy?)

Thanks,

EdMO

Edited by Ed In Missouri

Share this post


Link to post
Share on other sites

Posted

The breaker should be the next size bigger than the alternator output amperage, and the wire should be big enough not to melt down at the apperage rating of the breaker. So lets say you have a 30 amp alternator. Choose a 40 amp breaker and wire the alternator with wire that will not melt or quickly catch on fire with 40 amps passing thru it momentarily. If you use a wire rated for  30 amps continuous without generating too much heat, it should also work fine to carry 40 amps long enough not to melt before the breaker blows. That way if the alternator runs away you can pull the breaker and disconnect as quickly as you figure out what happened. If the alternator should short circuit, the wire will not melt before the breaker blows automatically from the battery being shorted to ground thru the alternator.

 

So you end up with manual overvoltage protection and automatic alternator short circuit protection.

 

Did that meke sense?

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0