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Time delay, flicker filter etc.

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gilles.thesee(at)free.fr
Guest

Posted: Mon Apr 28, 2014 4:07 am Post subject: Time delay, flicker filter etc.

Hi Bob and all,



It's been a long time since my last post on this knowledgeable list.

Our two battery / ABMM / Rotax 914 project has been flying for ten happy 

years now, except for one little problem that has kept nagging at us 

from the beginning.

The auxiliary battery management module (ABMM) works as advertised, 

connecting and disconnecting the aux battery contactor following the 

main bus voltage. But at idle, the voltage undergoes rapid fluctuations, 

leading to frigthening contactor chattering fits.

As a workaround we ended connecting the aux battery manually.



I was wondering if an easy way of introducing time delay in the voltage 

sensing side *or* actuating side of the ABMM could be devised ?

A time constant of 2 second would be adequate I suppose.

Could some variation of the fuel level flicker filter do ?



Thanks in advance for your suggestions, and keep on the good job !



Best regards,

-- 

Gilles

http://contrails.free.fr

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 28, 2014 1:30 pm Post subject: Time delay, flicker filter etc.

 	  Quote: 	
		  

A time constant of 2 second would be adequate I suppose.

Could some variation of the fuel level flicker filter do ?



Thanks in advance for your suggestions, and keep on the good job


	


    Referring to the assembly details in . . .



http://tinyurl.com/nxmo3us



    That comparator only has about 0.5% hysteresis . . .

    try reducing the value of R108 down to 100K

    which will raise the hysteresis by a factor of ~5x



   Bob . . .

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gilles.thesee(at)free.fr
Guest

Posted: Tue May 06, 2014 3:07 pm Post subject: Time delay, flicker filter etc.

Robert L. Nuckolls, III a écrit :

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>

>

> A time constant of 2 second would be adequate I suppose.

> Could some variation of the fuel level flicker filter do ?

>

> Thanks in advance for your suggestions, and keep on the good job



    Referring to the assembly details in . . .



 http://tinyurl.com/nxmo3us



    That comparator only has about 0.5% hysteresis . . .

    try reducing the value of R108 down to 100K

    which will raise the hysteresis by a factor of ~5x 


	


Hi Bob,



Thank you for responding.

What I did not state clearly is that somewhere along the build we 

switched from Aeroelectric's battery management module to Perihelion's 

because for some reasons we could not discover, the ABMM did not like 

the presence of EV200 contactors.

Since the new battery management module is potted, I was wondering if a 

proper filter could be devised as a "bolt-on" unit to be insered in 

series on the sense - or the contactor actuation - side.



Best regards,

-- 

Gilles

http://contrails.free.fr

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue May 06, 2014 3:36 pm Post subject: Time delay, flicker filter etc.

 	  Quote: 	
		  

Hi Bob,



Thank you for responding.

What I did not state clearly is that somewhere along the build we 

switched from Aeroelectric's battery management module to 

Perihelion's because for some reasons we could not discover, the 

ABMM did not like the presence of EV200 contactors.

Since the new battery management module is potted, I was wondering 

if a proper filter could be devised as a "bolt-on" unit to be 

insered in series on the sense - or the contactor actuation - side.


	


   oh . . . okay . . . wish we'd talked about

   this earlier . . .



   The EV200 contactors are known noise sources.

   Not sure why, it's not difficult to control.

   I think I've got a sample from the factory

   around here somewhere. Might see if I can

   get a peek at it in the lab with some really

   good equipment.



   In the mean time, I take it that the original

   ABMM is no longer available. You'd have

   to check with Eric on his recommendations

   but I'm guessing that you might get away

   with feeding the ABMM's + input terminal

   through a diode (Schottky would be best

   but not critical). Then put a capacitor

   across the ABMM input power terminals . . .

   something like 100uF. This would drive the

   module at the higher voltage more consistent

   with the peaks.



   As an aside, I'm studying a line of rectifier

   regulators for PM alternators, both single

   and 3-phase, that are head-and-shoulders above

   legacy technologies for voltage regulation

   stability.



   Further, they are thermally robust. The

   Ducati R/R supplied with the Rotax engines

   is pretty sorry compared to these new ones.

   Just getting a REAL regulator on your airplane

   may make Eric's ABMM happier too.





   Bob . . .

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gilles.thesee(at)free.fr
Guest

Posted: Thu May 15, 2014 7:44 am Post subject: Time delay, flicker filter etc.

Robert L. Nuckolls, III a écrit :

 	  Quote: 	
		  

 .... I take it that the original

   ABMM is no longer available. You'd have

   to check with Eric on his recommendations

   but I'm guessing that you might get away

   with feeding the ABMM's + input terminal

   through a diode (Schottky would be best

   but not critical). Then put a capacitor

   across the ABMM input power terminals . . .

   something like 100uF. This would drive the

   module at the higher voltage more consistent

   with the peaks. 


	


Hi Bob,



Thank you once again for your response and advice.

The original ABMM may still be somewhere in a drawer, I'll try to 

retrieve it.



Many many moons ago I crafted a little webpage on the subject :

http://contrails.free.fr/elec_lvwm_en.php

It could help to clarify things.



Will keep you posted on the result of the proposed mod.



Best regards,

-- 

Gilles

http://contrails.free.fr

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