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12V Battery open voltage low?

Discussion in 'Prime Technical Discussion' started by Robyn Jackey, Sep 29, 2017.

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  1. Robyn Jackey

    Robyn Jackey Junior Member

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    I recently moved my dashcam and power magic pro to my new Prime, and discovered that it rarely ever stays on for parking mode after I turn the car off. It turns out the 12V battery voltage is a bit lower than I would expect. Right after the car is turned off, the 12V battery measures ~12.05V at the terminals, and slightly lower at the fuse panel. If the headlights were on, then they stay on for 30 seconds after I leave the car, and the terminal voltage is more like 11.85 until they turn off. This is certainly preventing the dashcam for monitoring parking mode since the lowest cutoff voltage setting on my power magic pro is 12.0V.

    Wondering if others also see a low open voltage on their 12V battery in the Prime? I would expect more like 12.6V as this appears to be a normal sized (45Ah) lead acid battery.
     
    #1 Robyn Jackey, Sep 29, 2017
  2. bisco

    bisco cookie crumbler

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    yes, that is very low. put a charge on it, and see if it holds. if not, return it under warranty.
     
    #2 bisco, Sep 29, 2017
  3. Deleted member 111882

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    Reading 12.6 to 12.9 Volts on mine according to my ScanGauge. Your reading of 11.9 to 12.1 Volts doesn't sound comforting.
     
    #3 Deleted member 111882, Sep 29, 2017
  4. Sam Spade

    Sam Spade Senior Member

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    BUT......it may not be as "open" as you think when you are measuring.

    Get everything ready.....hood up etc. and then let it sit for an hour before checking the voltage.
     
    #4 Sam Spade, Sep 29, 2017
  5. priuscatprimeguy

    priuscatprimeguy Senior Member

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    I didn't bother with fooling around with the car battery. I have two dashcams connected to a 26800 MAH LI ION battery. I swap em out every 12 hours.
     
    #5 priuscatprimeguy, Sep 29, 2017
  6. Lee Jay

    Lee Jay Senior Member

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    Depends on the charge and load status. I see around 12.9 right after I shut off the car. But after I've charged a model airplane battery or two off the 12V battery, the voltage during charge draw drops to about 11.6-11.8V, with a 10A draw. Put the car in ready mode and it goes right to 14.5V.
     
    #6 Lee Jay, Sep 29, 2017
  7. Robyn Jackey

    Robyn Jackey Junior Member

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    Ok, this confirms my suspicion that it is not normal, so definitely going to pop back into the dealer and ask for a replacement.
     
    #7 Robyn Jackey, Oct 1, 2017
  8. Sam Spade

    Sam Spade Senior Member

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    A replacement for what exactly ?
    And what is a "power magic pro" ??

    IF......the car sat on the dealers lot for a LONG time and you haven't really driven it much since you got it, the battery might just need a good charge from an external source.
     
    #8 Sam Spade, Oct 1, 2017
  9. priuscatprimeguy

    priuscatprimeguy Senior Member

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    Power Magic Pro BlackVue Vehicle Battery Discharge Prevention for Parking Mode for BlackVue DR500GW, DR550GW, DR650GW, DR650S
     
    #9 priuscatprimeguy, Oct 1, 2017
  10. VTBIGDOG

    VTBIGDOG Active Member

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    Page 715 of the manual state the open battery voltage at 68 degrees is...

    ...12.0 V or higher. If the voltage is lower than the standard value, charge the 12-volt battery. (Voltage is checked 30 seconds after the hybrid system and all lights are turned off.)

    Posted via the PriusChat mobile app.
     
    #10 VTBIGDOG, Oct 1, 2017
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  11. Sam Spade

    Sam Spade Senior Member

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    Practical experience......and battery voltage charts from the battery makers.......tells us that 12.0 is not enough because that indicates the battery is about 50% discharged.

    If it reads 12.0 with virtually no load, as soon as the car tries to "start" all the electronics it will go below that (maybe a lot) and the computers and such don't like that.
     
    #11 Sam Spade, Oct 1, 2017
  12. bisco

    bisco cookie crumbler

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    could be the prius battery is not robust enough for your aftermarket accessories.
     
    #12 bisco, Oct 1, 2017
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  13. priuscatprimeguy

    priuscatprimeguy Senior Member

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    and THAT's why I use a 26800 MAH LI ION battery to power my dash cams. It's a little bit of a hassle to swap out the batteries every 12 hours but hey, at least I'm not using the car's battery.:D
     
    #13 priuscatprimeguy, Oct 2, 2017
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  14. Lee Jay

    Lee Jay Senior Member

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    That's silly. Your 26,800mAh battery is likely a 1-cell, meaning it's got an energy storage capability of 26.8Ah*3.7V = 99Wh. The Prime's 12V battery has an energy storage capability of 45AH*12V = 540Wh. And if you run the dash cams only when the car is actually in the on condition, you're running it off the ~5,700Wh traction battery or the ~150,000Wh engine+fuel tank.
     
    #14 Lee Jay, Oct 2, 2017
  15. priuscatprimeguy

    priuscatprimeguy Senior Member

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    USB C Power Bank RAVPower 26800 PD Portable Charger 26800mAh(Faster Recharged in 4.5 Hours &USB-C Input, 30W Type-C Output)for Nintendo Switch, USB Type-C Laptops, 2016 MacBook Power Delivery Support
     
    #15 priuscatprimeguy, Oct 2, 2017
  16. priuscatprimeguy

    priuscatprimeguy Senior Member

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    I have the dash cams on 24/7
     
    #16 priuscatprimeguy, Oct 2, 2017
  17. Cfrea

    Cfrea Junior Member

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    I'm having the same issue with my battery. I drive more than enough, yet the battery during operation sits at around 11.6 to 11.9 volts. This seems way too low and isn't correct. I can't even power a dashcam off it for parking mode.
     
    #17 Cfrea, Oct 24, 2017
  18. Robyn Jackey

    Robyn Jackey Junior Member

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    It oddly tested fine at the dealer, at least by their metrics. I had previously set the headlights to not stay on 30 seconds after I leave the car, which seemed to help some. Interested to see what you get if you have your tested too. 1508887690691.jpeg

    Posted via the PriusChat mobile app.
     
    #18 Robyn Jackey, Oct 24, 2017
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  19. bisco

    bisco cookie crumbler

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    what is parking mode?
     
    #19 bisco, Oct 24, 2017
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  20. Robyn Jackey

    Robyn Jackey Junior Member

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    Some dashcams (blackvue, etc) can record when parked and motion is detected. I hardwired mine too the fuse box with a power magic pro that cuts off the camera power of it reaches a minimum battery voltage or a timer, to avoid discharging the 12V battery too much.

    Posted via the PriusChat mobile app.
     
    #20 Robyn Jackey, Oct 24, 2017
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