Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Shunt Readings

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

Speedy11(at)aol.com
Guest

Posted: Tue Sep 22, 2009 6:29 am Post subject: Shunt Readings

Bob or somebody -

 Please verify (or debunk) what I perceive is happening with the readings  from my shunt.

 Background:

 RV-8A

 Two busses - main (operates everything normally) and standby (operates  essentials if alt + main fail)

 One alternator, two batteries - one fore (main batt - main bus + engine  start) & one aft (stby bus - no start)

 HE device on wire from alternator to main batt (HE device and main batt  located aft of firewall)

 Shunt on standby batt located aft of rear baggage.  Battery power  is wired to shunt.  Shunt is wired to contactor.  Contactor is  wired to standby bus.  So, all electrons pass from battery through shunt to  contactor to bus.

 When I turn on only standby batt contactor, the shunt load indicates about  2A (contactor resistance plus operation of engine monitor).

 After engine start and the alternator is carrying the load and the batts  have recharged, I occasionally get a negative amp indication on the shunt (most  of the time the shunt indicates 1 amp - probably contactor).

 Question:

 Can I assume that when the standby battery is being charged the shunt will  indicate negative amps?

 If not, what might cause a negative load indication on the shunt?

 Thanks,

 Stan Sutterfield

  [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Sep 22, 2009 7:18 am Post subject: Shunt Readings

 	  Quote: 	
		   

 Question:

 Can I assume that when the standby battery is being charged the shunt will indicate negative amps?

 If not, what might cause a negative load indication on the shunt? 	


    Without seeing power distribution diagram, I can't

    be real sure that I have an accurate mental image

    of your system's configuration. However, some general

    rules apply to battery ammeters . . .



    Depending on polarity of connections to the current

    sensor (in this case it's not a 'shunt'), the polarity

    of current readings will indicate either a charge (bus

    voltage above 13v) or a discharge (bus voltage

    below 13v). Your narrative seems to indicate that your

    battery current display is positive sign when the

    battery is being discharged; alternator(s) off.



    It follows then that when the alternator(s) lift the

    bus voltage to nominal set points, the battery will

    be recharged and the sign of battery current will

    reverse . . . in this case be (-).



 

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------



     [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum