"Battery Fail" - voltage discrepancy

Discussion in 'ALTA' started by Adam Etheridge, Dec 13, 2015.

  1. Adam Etheridge

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    Hi Everyone

    I contacted FreeFly support because I kept getting a "Battery Fail" warning during boot - Terminal was reporting that the battery was out of range at 25.6v. We're using pairs of Tattu 10,000mAh 6S Lipos.

    Freefly said that we may have "High Voltage model" batteries (?) and advised to set the charger to cut off at 4.19v, giving 25.1v total pack.... We've done exactly this, however there seems to be quite a large difference on what Alta considers to be the pack's voltage. See photo and screen grab below.

    A battery tester, multimeter, and charger all say the pack is 25.0v (+/- 0.2v)...
    However the Alta thinks it is 25.9v, and is still refusing to boot due reporting "Battery Fail".

    Does anyone else have this problem? Is this normal?!

    IMG_6064.JPG IMG_6060.PNG
     
  2. Rolf Ableiter

    Rolf Ableiter Active Member

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    what is strange to me: 6s should be 25,2 V
    your tester measured 25,04 with 97%
    this should be higher (something like 25,1 - 25,15). take a look a each cell - may there is a damage in one cell?

    but anyway: shouldn't there a voltage calibration function in the ALTA App? this would be nice...
     
  3. Adam Etheridge

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    The cells are fine - each between 4.16-4.18 (give or take) - I've also tried this on 4 separate packs and get the same result, and the same discrepancy:

    The Alta is saying the total pack voltage is approx +0.9v higher than all the other instruments I use, which seems a lot to me - and is therefore putting them 'out of range' and preventing Synapse from booting...
     
  4. Rolf Ableiter

    Rolf Ableiter Active Member

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    did you test any other batterie pack?
     
  5. Rolf Ableiter

    Rolf Ableiter Active Member

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    sorry - you did :)
     
  6. Adam Etheridge

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    Yeah 4 packs in total - same result :-/ ?
     
  7. Rolf Ableiter

    Rolf Ableiter Active Member

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    i have slightly other results than my tester and i think that's normal but freefly should install a calibration function for such a big measuring failure...
    sorry - i hope you get help from the support.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The evidence suggests that the voltage sensor on the ALTA is suspect, doesn't it?

    Just one thought: Can you measure the voltage of the battery while is connected to the ALTA and the ALTA is powered up but not armed. I think you're measuring the battery with the VOM/LiPo checker under "no load" conditions.

    Personally, I suspect you'll see the same results, but the Universe often surprises me.... :)

    Andy.
     
  9. Rolf Ableiter

    Rolf Ableiter Active Member

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    and if you use futaba: it would be interesting if the telemetry data is different.
     
  10. Adam Etheridge

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    Hi Andy - when connected to the Alta it drops very slightly from 25.04v to 25.00v, so almost nothing...
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks...so, as you pointed out, it looks like the ALTA is over-reporting the voltage and then banging up against a self-imposed (and not unreasonable) over-voltage limit.

    If you've not already done so, I'd communicate this back to support@freeflysystems.com.

    Andy.
     
  12. Adam Etheridge

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    Thanks for all your help guys - they've asked me return it for repair / recalibration...
     

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