Screen says 11.8 volt battery says the screen is wrong??

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by skydivetoday, Oct 7, 2020.

  1. skydivetoday

    skydivetoday Junior Member

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    Hello everyone,

    I have a 2014 V with 50,000 miles. It runs fine so I do not understand why the car screen says I have 11.8 volts but when I check at the battery it's 12.37 volts. The car is getting 49 to 52 avg. Mpg. Charging at 14.3 volt.

    Is this normal? Does this mean that the car systems are off?
     
  2. rjparker

    rjparker Senior Member

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    Be sure your voltmeter is accurate. The low cost harbor freight type often read high. My v reads about 12.3v when the car is on but not in Ready. Yours does seem low but not unreasonable depending on its age.

    Check voltage at the engine compartment fuse box (jump point) versus the screen readout. Compare that voltage against the meter's direct battery readout. You are then using the same meter for both readings, one at the battery, a second at the engine fuse box. If there is still a half volt difference it is possible the battery cables have corrosion causing the voltage drop. Also check the negative battery cable connection at the chassis.
     
    #2 rjparker, Oct 7, 2020
    Last edited: Oct 7, 2020
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  3. Tim Jones

    Tim Jones Senior Member

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    That is some great mpg for a v...... I have never got that. I think the mpg might be off also.....
     
  4. skydivetoday

    skydivetoday Junior Member

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    Good advice I shall do that reading after I check the cable.

    I get that mileage because I drive in florida town that has 45 mph limit.
     
  5. bisco

    bisco cookie crumbler

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    are you measuring the voltage at the jump point after the car has been off a few hours?

    the cars reading is with somewhat of a load
     
  6. ChapmanF

    ChapmanF Senior Member

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    The voltage displayed on the car screen is an accurate voltage reading, it's just reading the voltage at a point somewhere inside the car screen electronics themselves. That's downstream of the battery by one or two fuse links, at least one branch fuse, and a dozen or so feet of wire.

    You're seeing a difference between the two of about 0.57 volts. That's in the same ballpark as I see in my 2010 liftback, and used to see in my 2001 sedan.

    Did you take the reading in ACC or in ON? Typically the difference will be a bit more in ON than in ACC because more current is being drawn.
     
  7. skydivetoday

    skydivetoday Junior Member

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    I checked the terminals ,they where on well and clean. I then took reading at the battery and the front fuse box. They where the same. The on the screen is was 1/2 volt less. This tells me my that my toyota scan tool my be off.
     
  8. ChapmanF

    ChapmanF Senior Member

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    In this last post you mention "on the screen" and also "toyota scan tool". I'm not quite following the details here.

    As for the voltage on the MFD "vehicle signal check" screen, for that to be about half a volt less is consistent with what I've seen in every Prius where I've checked.
     
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  9. jzchen

    jzchen Senior Member

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    At 12.37 V Toyota says charge and retest. If that is measured just after stopping the car or after charging might be time to start looking for a replacement.

    moto g(7) power ?
     
  10. skydivetoday

    skydivetoday Junior Member

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    Because of the MFD is off I think the mini vci would be getting the same information.
     
  11. bisco

    bisco cookie crumbler

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    i think you're fine, nothing is likely off
     
  12. rjparker

    rjparker Senior Member

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    All that means is there is no appreciable voltage drop front to back. That says your battery connections and grounds are reasonable. You could still have a voltmeter that is off.
     
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  13. Tim Jones

    Tim Jones Senior Member

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    Go to Auto Parts and have battery load tested...if ok I'd forget it.
     
  14. ChapmanF

    ChapmanF Senior Member

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    Hmm, I never clearly saw from your earlier posts where you were reading off the MFD and where you were reading from a Mini VCI.

    The voltage reading from the MVCI should be a straight measurement of the voltage on pin 16. It doesn't have to communicate with the car's computers or anything for that. You could probably have the Mini VCI out of the car and just connect a known voltage source to pin 16, and compare what reading it gave you.
     
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