Ground External Power with G1000

Discussion in 'Avionics and Upgrades' started by GaryRudolph, Jul 16, 2017.

Tags:
  1. GaryRudolph

    GaryRudolph Filing Flight Plan

    Joined:
    Jul 16, 2017
    Messages:
    3
    Location:
    Orinda, CA
    Display Name:

    Display name:
    Gary
    Just picked up an aircraft with a G1000 and I'm trying to do some training on the ground. I connected a JAC2024H to the external power and when I start the PFD with the Master Battery switch it shows negative AMPS for the M BAT. Is this normal with ground power? Is there a handshake I'm missing?
     
  2. gsengle

    gsengle Pattern Altitude

    Joined:
    May 9, 2016
    Messages:
    1,774
    Display Name:

    Display name:
    Gsengle
    Depends on the airplane in all likelihood. Have your AFM?


    Sent from my iPhone using Tapatalk
     
  3. jordane93

    jordane93 Final Approach

    Joined:
    Sep 9, 2013
    Messages:
    8,417
    Location:
    Long Island, NY
    Display Name:

    Display name:
    Jordan
    According to the manual on 7-53 it says, if the M BAT ammeter does not show a positive charge, the battery should be serviced before flight.
     
    Last edited: Jul 16, 2017
  4. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

    Joined:
    Aug 18, 2015
    Messages:
    1,826
    Location:
    KLAF
    Display Name:

    Display name:
    455 Bravo Uniform
    On my 182, per the service manual, ground power opens a normally closed relay on the electronics side of the bus. I'd have to put power on the battery to mess around with my radios, etc. But I'm a newb, that's my understanding, may be wrong.
     
  5. GaryRudolph

    GaryRudolph Filing Flight Plan

    Joined:
    Jul 16, 2017
    Messages:
    3
    Location:
    Orinda, CA
    Display Name:

    Display name:
    Gary
    I'm in a 206, and I thought ground power would open just by connecting it. The POH doesn't have much on it to just run avionics without starting. I'll reread again.

    On the ground power it never leaves flood charging mode. The ground power green light is on, but the yellow charging is not.
     
  6. DGlaeser

    DGlaeser Pre-takeoff checklist

    Joined:
    Oct 16, 2008
    Messages:
    160
    Location:
    Rochester Hills, MI
    Display Name:

    Display name:
    DGlaeser
    We've had problems with the ground power relay not closing properly. When that happens no ground power is getting to the system. When you turn on the ground power (big red plug in place), you should hear a contactor 'click'.
    When in doubt, remove the top cowl and connect directly to the battery. If that shows charging on the G1000, then you need to get the ground power system serviced.
     
  7. GaryRudolph

    GaryRudolph Filing Flight Plan

    Joined:
    Jul 16, 2017
    Messages:
    3
    Location:
    Orinda, CA
    Display Name:

    Display name:
    Gary
    Had a shop look at it and the connectors had to be cleaned. It wasn't triggering the relay.
     
  8. Frank Palmieri

    Frank Palmieri Filing Flight Plan

    Joined:
    Jul 4, 2018
    Messages:
    1
    Display Name:

    Display name:
    Frank P
    I don't mean to hack this thread but I have the same problem. I connected my GPU and turned on my master and Avionics switches and my G1000 is indicating a -11.2 draw. Any suggestions? The instructions on the GPU are very lame so I'm not sure I'm doing the proper procedures to use a GPU. I have a 2007 182T. Thanks
     
  9. oilburner

    oilburner Pre-takeoff checklist

    Joined:
    Feb 11, 2014
    Messages:
    249
    Location:
    Midland TX
    Display Name:

    Display name:
    oilburner
    I use a Start Pac, but often have to wiggle the plug into the recepticle on my C-182T just right to get the negative current draws to go away.
     
  10. Larry in TN

    Larry in TN Line Up and Wait

    Joined:
    Nov 16, 2013
    Messages:
    945
    Location:
    Nashville, TN
    Display Name:

    Display name:
    Larry in TN
    Is there a separate ground power switch?
     
  11. Dan Thomas

    Dan Thomas En-Route

    Joined:
    Jun 16, 2008
    Messages:
    4,597
    Display Name:

    Display name:
    Dan Thomas
    You are using a 24-volt power supply, right? 28-volt output? I'm assuming this is a 28-volt airplane.

    There's a diode between the third pin (the small pin) and the external power contactor in the Master Control Unit. The external power receptacle is on that box. If the diode is shot, and they do burn out, the contactor doesn't close. Lamar doesn't specify the part number for that diode in any of their literature, and Cessna says it's a vendor item. I had to weasel the part number out of a Lamar engineer. Now, I can't remember what it was, and I'm retired. 1N4007, maybe?
     
    Last edited: Jul 15, 2018