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Technical Problem with Amp Meter

Discussion in 'The Hokey Ass Message Board' started by Ralphies54, Aug 25, 2019.

  1. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    Other than a bad gage is there any other reason the gage reads 0 (straight up) when the alternator is putting 13.8 - 14 Volts into the battery under a load, (Lights on, radio on etc) Car is a friends 64 327 Vette. Thanks, Ralphie
     
  2. theboss20
    Joined: Dec 30, 2018
    Posts: 274

    theboss20

    Any wires been moved or worked on around the starter or battery? Has the gauge worked recently?


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  3. Ken Smith
    Joined: Dec 6, 2005
    Posts: 413

    Ken Smith
    Alliance Vendor

    If the engine is running and the battery is fully charged, the alternator will be supplying all the current necessary for the lights and radio. The amp gauge will read “0” since the battery is not contributing to the power required to run those items.


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  4. theboss20
    Joined: Dec 30, 2018
    Posts: 274

    theboss20

    True...so turn on the headlights and leave them on for 30 min. and then start the car...if this is the issue you should see deflection in gauge at that time...


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  5. It's a voltmeter, right ?
     
  6. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    To my knowledge the meter has not been working for a long time, but the battery remains charged.
    Would not the gage at least flicker to the - side with a full elect load and the engine off?
     
  7. Ken Smith
    Joined: Dec 6, 2005
    Posts: 413

    Ken Smith
    Alliance Vendor

    turn the engine off and turn on the headlights. The amp gauge should show “-“. The battery is supplying the power for the lights. After a time, start the engine. The amp gauge should show “+” as the alternator charges the battery.


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  8. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    I'll try that, thanks
     
  9. Budget36
    Joined: Nov 29, 2014
    Posts: 13,173

    Budget36
    Member

    Check it's resistance, should be really low...i/e less than 2 ohms.

    But, with engine off, just turning the headlights on should deflect the meter to the left (-) side.

    I'd think if the Ammeter was open/bad, the battery wouldn't charge.
     
  10. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    Ampmeter
     
  11. theboss20
    Joined: Dec 30, 2018
    Posts: 274

    theboss20

    If the gauge has a zero straight up...it's an ammeter...


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  12. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    Check Where, across the gage or the wiring??
     
  13. theboss20
    Joined: Dec 30, 2018
    Posts: 274

    theboss20

    I believe this style gauge to be a "shunt" gauge which would allow the battery to charge and could be the key to the issue...bad shunt.


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  14. Boneyard51
    Joined: Dec 10, 2017
    Posts: 6,440

    Boneyard51
    Member

    Depends where in the circuit the amp gauge is placed as to what it shows.





    Bones
     
    firstinsteele likes this.
  15. Ralphies54
    Joined: Dec 18, 2009
    Posts: 772

    Ralphies54
    Member

    lothiandon1940 likes this.

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