Garmin GPS lll+ Voltage readout incorrect

Discussion in 'Equipment' started by 2Laud 2Bro, Dec 5, 2002.

  1. 2Laud 2Bro

    2Laud 2Bro Been here awhile

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    Reads .5 volts low. Indicates 12.1 volts on display when battery voltage is 12.6 volts measured with a meter. Motor running indicates 13.7 volts.

    Is this typical of a GPS lll+ voltage readout?
    #1
  2. Marc

    Marc Just sayin...

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    Good Question. I've just assumed that the digital readout on my SP176c was correct. I'm gonna have to test it w/my DVM. I'll get back to you on this. :thumb

    BTW, I'm moving this to the Equipment forum 'cause it's the place for this.

    Marc
    #2
  3. markgsnw

    markgsnw WTF?

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    where are you measuring voltage with your meter and where is the GPS measuring the voltage? May not be the same.


    mark
    #3
  4. tbirdsp

    tbirdsp REMF

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    How do I get the III+ to display voltage? Sorry if it's been covered before.
    #4
  5. Gary

    Gary Another Adventure Rider

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    First, it has to be connected to an external power source, then you can select the field from the pick list for display, but only on a couple of screens, I can't remember which one, but you'll see it as soon as you plug into a battery.

    I power mine direct from the battery, and the reading is in aggreement to my Radio Shack $27 POS volt meter.

    Good thing to have if you're riding an airhead.

    Gary
    #5
  6. tbirdsp

    tbirdsp REMF

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    Thanks man. I have the III+ on a Touratech mount wired for bike power on my DRZ. I'm gonna put heated grips on and would like to monitor voltage. The battery on the DRZ is tiny, probably not much charging system either.
    #6
  7. 2Laud 2Bro

    2Laud 2Bro Been here awhile

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    The page that displays "voltage" is the Position Page, owners manual pages 30-32. The data fields displayed can be chosen- page 32.

    I am glad to hear that at least one unit displays accurate voltage, mine does not. Measured with two different digital voltmeters at the plug that goes directly into the GPS. DVM's indicate 12.6 volts and when the GPS is plugged in and powered up voltage displayed is 12.1 volts. At the same time a DVM measured 12.6 volts off of the heated clothing plug which connects directly to the battery. A .5 volt error.

    In the house, 4.3 volts is indicated on GPS right now as it is running off the four AA batteries (1.5 volts each). The battery bar is at about 1/8th height. New batteries might fix the .5 volt error, but not counting on it because the error occurs when using the GS's battery for power.

    Ride alert, ride smart. Winter gear and the GPS can be a distraction.
    #7
  8. tbirdsp

    tbirdsp REMF

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    I'm not convinced you have an error. Isn't it possible the powered up GPS is causing the voltage in that circuit to drop to 12.1? About the only postive check would be to read the voltage at the GPS plug while the unit was powered up, tricky to do.
    Any electrical wiz kids feel free to step in here though.
    #8
  9. tbirdsp

    tbirdsp REMF

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    All I have is a crappy analog volt meter, but I checked it out anyway. GPS indicated 11.7 volts (bike not running, in a cold garage) and volt meter showed about 12.1 at the plug. Looks like a similar discrepancy to what you've got.
    #9
  10. 2Laud 2Bro

    2Laud 2Bro Been here awhile

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    Thanks tbirdsp.

    Thinking it's displaying some internal GPS voltage instead of the battery voltage (not running) or alternator output voltage (running).

    One more verification and it's true.
    #10
  11. Gerg

    Gerg The Destroyer

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    Couple of things here... First, it's normal, somewhere around a .5 volt drop.
    Second, the reason. The wiring harness has very small wire. There's some voltage drop there. If you have an in line fuse there is some additional drop there. The 4 pin plug has some loss as well. Add it all up and you get the .5. It's the same on both my bikes (got mounts on both of them with a hardwire set-up). The good news it that it's pretty constant. Just watch for anything that goes below 11 ~ 11.5 volts to indicate a problem.

    HTH
    Gerg
    #11
  12. tbirdsp

    tbirdsp REMF

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    Gerg, not to beat this to death, but we are seeing a .5 drop between voltage checked with a meter *at the 4 prong plug pins* and indicated on the GPS. The voltage drop due to the wire, fuse, plug, etc aren't included in this. Sounds like you are talking .5 drop between GPS and direct check at the battery terminals.
    I assume just the GPS unit is enough to cause this drop though.
    #12
  13. 2Laud 2Bro

    2Laud 2Bro Been here awhile

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    Thanks guys. .5 volt difference is normal. I like to watch the voltage to monitor charging system function and battery life.
    #13