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Rotax 912 Charging Problem

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Mon Sep 28, 2009 10:48 am Post subject: Rotax 912 Charging Problem

 	  Quote: 	
		   I have a Rotax 912 UL engine on an Allegro 2000 LSA. Recently I have had to replace my battery (12V 18Ah) because of it's inability to crank the engine. Prior to replacing the battery I noticed my combination Volt/Amp meter showed only 12 volts while flying. Usually the voltmeter shows about 13.5 volts at start-up while the engine is running on the ground and while flying. After replacing the battery, and starting the engine the voltmeter returned to 13.5 volts. However, when I began to close certain circuit breakers engaging the front landing light, the two wing tip landing lights, the two wing tip strobes, and the nav. lights I noticed the volt meter dropping back each time I engaged one of the breakers until finally the volt meter again was indicating only about 12 volts just as before. I have a "no charge" red light in the battery charging circuit that comes on if the battery is not being charged while the engine is running. This  light normally does not come on unless the engine is at very low rpm ( aprx.1400 rpm). This is not normal for my engine for my idle speed is set at 1800 rpm. 

  

 I do not know why the voltage is dropping each time I close the breaker for lights described above, or what may be causing the voltage drop. I know I have a good battery, but I don't know if my regulator is going bad, or if there may be aground some where, or somthing else. Can anyone shed any light on what may be causing this? The engine has only 255 hours on it and I have not had any other problems with the engine. Any help would be greatly appreciated.

  

 Hugh G. McKay III

 Allegro 2000

 Rotax 912 UL

 N661WW

  

 hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net) 

  

	
  [quote][b]

pchristensen10(at)austin.
Guest

Posted: Mon Sep 28, 2009 10:57 am Post subject: Rotax 912 Charging Problem

Had the same problem with my Kitfox III/912. Asked the  same questions. Replaced the rectifier/regulator. Problem solved.

  

 Pete

  

 [quote]   ---

rampil

Joined: 04 May 2007
Posts: 870

Posted: Mon Sep 28, 2009 11:05 am Post subject: Re: Rotax 912 Charging Problem

Hi Hugh,



Remember that nasty lump on the rear end of your 912.

That's the alternator.  It supplies electricity to run things

on your airplane when the engine is going.  The alternator

supplied as an integral part of the 912 can only supply 16 amps or

so at 5500 rpm at 13.5volts.  When you turn on on enough

electrical load, you are asking for more than the poor little thing

can supply.  The regulator does not create power out of thin air,

it only smooths out the voltage until it can't any more.



If you don't shut off some of that electrical junk, the voltage will not be

high enough to charge your battery.



You can put on a new 40A alternator for about $800.  It will suck those

extra amps right out of your propeller if you do.



I would also recommend you read a bit about aircraft or automotive

electrical systems.

_________________
Ira N224XS

pwmac(at)sisna.com
Guest

Posted: Mon Sep 28, 2009 12:13 pm Post subject: Rotax 912 Charging Problem

Your solution is best found by signing up the the aeroelectric list on Matronics.

  Quickly your volts are to low 13.8 to 14.2 or so indicates a healthy charging system at engine speed just above idle. You have your low voltage light wired wrong. You should  have a low voltage indicator light on your battery buss and then it would come on at at voltage below 13. Your battery is not being charged  because the output of the reg is way to low. Probably time for a new regulator, but the electric guys will tell you how to determine if the alternator is providing the good stuff to the reg.



 BTW FYI, a good battery should have  more than 12.6 volts after sitting unused for a day. And that doesn't mean it will provide enough amps to start the engine. To find that out you need to run a load test.



 Step 1 is to take the battery out and get it load tested then go for there to check out other possibilities.

 Paul

 ===========

 At 12:07 PM 9/28/2009, you wrote:



 [quote]  I have a Rotax 912 UL engine on an Allegro 2000 LSA. Recently I have had to replace my battery (12V 18Ah) because of it's inability to crank the engine. Prior to replacing the battery I noticed my combination Volt/Amp meter showed only 12 volts while flying. Usually the voltmeter shows about 13.5 volts at start-up while the engine is running on the ground and while flying. After replacing the battery, and starting the engine the voltmeter returned to 13.5 volts. However, when I began to close certain circuit breakers engaging the front landing light, the two wing tip landing lights, the two wing tip strobes, and the nav. lights I noticed the volt meter dropping back each time I engaged one of the breakers until finally the volt meter again was indicating only about 12 volts just as before. I have a "no charge" red light in the battery charging circuit that comes on if the battery is not being charged while the engine is running. This light normally does not come on unless the engine is at very low rpm ( aprx.1400 rpm). This is not normal for my engine for my idle speed is set at 1800 rpm. 

   

  I do not know why the voltage is dropping each time I close the breaker for lights described above, or what may be causing the voltage drop. I know I have a good battery, but I don't know if my regulator is going bad, or if there may be aground some where, or somthing else. Can anyone shed any light on what may be causing this? The engine has only 255 hours on it and I have not had any other problems with the engine. Any help would be greatly appreciated.

   

  Hugh G. McKay III

  Allegro 2000

  Rotax 912 UL

  N661WW

   

  hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net) 

   



  

 [b]

hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Mon Sep 28, 2009 2:04 pm Post subject: Rotax 912 Charging Problem

Ira:

  

 My Rotax 912 UL installation manual shows on page 47 that the engine will produce 20 amps at 5000 rpm, and 18 amps at 4000 rpm at 13.5 volts DC. My total electrical load is 16.7 amps with a 100% load factor. The real load factor is more like 70% which gives an actual load of 11.7 amps. Where do you get the 16 amp maximum? Also I di not have this problem until just recently.

  

 Hugh 



--- On Mon, 9/28/09, rampil <ira.rampil(at)gmail.com> wrote:



  	  Quote: 	
		  

From: rampil <ira.rampil(at)gmail.com>

Subject: Re: Rotax 912 Charging Problem

To: rotaxengines-list(at)matronics.com

Date: Monday, September 28, 2009, 3:05 PM



 --> RotaxEngines-List message posted by: "rampil" <ira.rampil(at)gmail.com (ira.rampil(at)gmail.com)>



Hi Hugh,



Remember that nasty lump on the rear end of your 912.

That's the alternator.  It supplies electricity to run things

on your airplane when the engine is going.  The alternator

supplied as an integral part of the 912 can only supply 16 amps or

so at 5500 rpm at 13.5volts.  When you turn on on enough

electrical load, you are asking for more than the poor little thing

can supply.  The regulator does not create power out of thin air,

it only smooths out the voltage until it can't any more.



If you don't shut off some of that electrical junk, the voltage will not be

high enough to charge your battery.



You can put on a new 40A alternator for about $800.  It  will suck those

extra amps right out of your propeller if you do.



I would also recommend you read a bit about aircraft or automotive

electrical systems.



--------

Ira N224XS





Read this topic online here:



http://forums.matronics.com/viewtophref="http://www.matronics.com/Navigator?RotaxEngines-List"  target=_blank>http://www.matronics.com/Navigator?RotaxEngines-List[b]



	
  [quote][b]

hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Mon Sep 28, 2009 5:44 pm Post subject: Rotax 912 Charging Problem

Pete:

  

 What brand/type regulator did you have that failed? What type/brand did you replace it with?

  

 Hugh McKay



--- On Mon, 9/28/09, Pete Christensen <pchristensen10(at)austin.rr.com> wrote:



 [quote]

From: Pete Christensen <pchristensen10(at)austin.rr.com>

Subject: Re: Re: Rotax 912 Charging Problem

To: rotaxengines-list(at)matronics.com

Date: Monday, September 28, 2009, 2:54 PM



    Had the same problem with my Kitfox III/912. Asked the same questions. Replaced the rectifier/regulator. Problem solved.

  

 Pete

  

 [quote] ---

rampil

Joined: 04 May 2007
Posts: 870

Posted: Tue Sep 29, 2009 4:39 am Post subject: Re: Rotax 912 Charging Problem

Hi Hugh,



Yes, the latest install manual has a plot of output vs rpm which

implies 20 A at 5000.  However, the same manual also has a limit

of 250 W on the alternator which at 13.5 is 18 A.



In my original install manual, the limit was 17 A at 5800 rpm, derated

to 16 A at 5500 rpm.



To my knowledge, there has been no power output upgrade to the 

alternator since 2002 when my engine was delivered.



Your problem seems to be completely explained by excessive load on

the alternator and has nothing to do with the battery.



Therefore, I may be crazy, but I am going to stand with my explanation

given the limited info you supplied, and say that the new Install

Manual is "generous"

_________________
Ira N224XS

rlborger(at)mac.com
Guest

Posted: Tue Sep 29, 2009 5:07 am Post subject: Rotax 912 Charging Problem

Hello Hugh,



I'll add my two cents to say that I agree completely with Ira.  The stock alternator on the Rotax 9xx series engine is hard pressed to turn out more than 15 amps at 13.8 volts.  And if you do try to run more than that through the Ducatti regulator the regulator will die.



I suggest you sort out your power requirements to keep them under 15 amps for most of the flight so there some extra amps available to recharge the battery.  Then you can add the landing lights and other power hogs at the end of the flight if they are needed.  And find one of those Schumacher battery tenders that 'lectric Bob recommends and use it to keep your battery happy between flights.



Check six,

Bob Borger

Europa XS, Rotax 914, Airmaster C/S prop

 

On Tuesday, September 29, 2009, at 07:39AM, "rampil" <ira.rampil(at)gmail.com> wrote:

 	  Quote: 	
		  



Hi Hugh,



Yes, the latest install manual has a plot of output vs rpm which

implies 20 A at 5000.  However, the same manual also has a limit

of 250 W on the alternator which at 13.5 is 18 A.



In my original install manual, the limit was 17 A at 5800 rpm, derated

to 16 A at 5500 rpm.



To my knowledge, there has been no power output upgrade to the 

alternator since 2002 when my engine was delivered.



Your problem seems to be completely explained by excessive load on

the alternator and has nothing to do with the battery.



Therefore, I may be crazy, but I am going to stand with my explanation

given the limited info you supplied, and say that the new Install

Manual is "generous"



--------

Ira N224XS





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 65520#265520

pchristensen10(at)austin.
Guest

Posted: Tue Sep 29, 2009 5:11 am Post subject: Rotax 912 Charging Problem

Hugh,  

  

 I used the stock unit from Rotax.  It is easy to  install.  I did add an aluminum heat sink thinking it would help keep  things cool.  Mine failed at about 400 hours.  My regulator is behind  my panel not in the engine area.

  

 Pete

  

 [quote]   ---

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Tue Sep 29, 2009 5:37 am Post subject: Rotax 912 Charging Problem

Hugh,

  I had a similar problem with not enough voltage. I have a Monroy traffic alerter in my aircraft (a GOOD thing !). It monitors your buss voltage when it is not detecting other aircraft. The female voice alerted me to "low voltage" and sure enough the gauge confirmed it.

  I removed the regulator and cleaned each of the terminals in the hope that it might be corrosion. That did the trick and I now have normal voltage. You might give that a try before buying another regulator. They are expensive.

                                                    Dick Maddux

                                                     Fox 4

                                                     Pensacola,Fl

  [quote][b]

bnelson79

Joined: 19 Mar 2011
Posts: 4

Posted: Sat Mar 19, 2011 5:34 pm Post subject: Rotax 912 Charging Problem

I am having a similar problem to the one Hugh McKay had a few years ago.  My problem though is simply that the battery is not being charged.  The voltmeter show 12 volts at startup and slowly drains down from there (faster if I turn accessories on).  Noticed this while flying yesterday when the voltmeter was pegged on the high end.  Landed and suddenly started getting a lot of static in headset.  Turned off heater and static disappeared, but voltmeter dropped to zero.  Noticed landing light had been accidentally turned on - turned off and volt needle swung to high side again.  As I turned switches off the needle would swing from high to low.  Finally shut down.  But when I tried to restart volt meter read only around 9 volts and engine wouldn't turn over at all.  Recharged battery today and engine started with 12 volts showing and none of the other switching problems.  But juice continued to dribble away.  

Any suggestions???  Bad ground???  Bad regulator???



Bill Nelson

Prosser, WA

N6576E

[quote="hgmckay"] 	  Quote: 	
		   I have a Rotax 912 UL engine on an Allegro 2000 LSA. Recently I have had to replace my battery (12V 18Ah) because of it's inability to crank the engine. Prior to replacing the battery I noticed my combination Volt/Amp meter showed only 12 volts while flying. Usually the voltmeter shows about 13.5 volts at start-up while the engine is running on the ground and while flying. After replacing the battery, and starting the engine the voltmeter returned to 13.5 volts. However, when I began to close certain circuit breakers engaging the front landing light, the two wing tip landing lights, the two wing tip strobes, and the nav. lights I noticed the volt meter dropping back each time I engaged one of the breakers until finally the volt meter again was indicating only about 12 volts just as before. I have a "no charge" red light in the battery charging circuit that comes on if the battery is not being charged while the engine is running. This  light normally does not come on unless the engine is at very low rpm ( aprx.1400 rpm). This is not normal for my engine for my idle speed is set at 1800 rpm. 

  

 I do not know why the voltage is dropping each time I close the breaker for lights described above, or what may be causing the voltage drop. I know I have a good battery, but I don't know if my regulator is going bad, or if there may be aground some where, or somthing else. Can anyone shed any light on what may be causing this? The engine has only 255 hours on it and I have not had any other problems with the engine. Any help would be greatly appreciated.

  

 Hugh G. McKay III

 Allegro 2000

 Rotax 912 UL

 N661WW

  

 hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net) 

  

	
   	  Quote: 	
		  [b]

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Mar 20, 2011 6:39 am Post subject: Re: Rotax 912 Charging Problem

Hi Bill,

(This is assuming everything was wired correctly from the start)



You could have a few things going on and each is easy to check. For different values you should have the "Heavy Maint" manual and use section 74-00-00 on electrical.

You may have a bad ground on the battery, engine ground, a bad wire from the reg/rec to the battery charge system. You may have a reg/rec going out. You can test a few of these with the engine running and a multimeter. Check the AC current going into the reg/rec, two bottom yellow wires. Check the "R" or reference output just above those yellow wires and check the "C" or charge output at the top of the reg/rec. That should be telling and should be 13.6V-14.0V. If you have a plane that was always okay and then started to have a problem I would look at all my grounds and reg/rec output. If you have a brand new plane I would still look at those items, but I would make sure my wire was large enough for the distances you have between the charging unit and instruments. Some people have used too small a wire gauge in the past. Also make sure you do not have the system drawing more current than the engine can deliver.



I would check my battery terminals for tightness first, then main ground wires and then the reg/rec input and out put before anything else.

Make sure you have clean battery terminals and make sure you have a good battery. Any battery can fail early.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

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