Support Look at this bizarre battery "drop"

Discussion in 'Android Devices' started by Tim K, Feb 16, 2012.

  1. Tim K

    Tim K Well-Known Member
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    I forget what app I had been using, but when I closed it, it appeared to cause a reboot - but that's not the point. When my phone booted back up, the 'reported battery level" went from about 65% to 50%. Very strange and adds more credence to the possibility that "battery issues" could actually be reporting issues.

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  2. hurricane630

    hurricane630 Well-Known Member
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    Mine actually did the same thing yesterday, im not sure why though either
     
  3. PhilosoRaptor

    PhilosoRaptor Well-Known Member
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    I've seen that a few times on my phone. Reboot and there's a big gap in battery percentage. Some how, I'm sure that the battery is just not able to report the remaining capacity accurately all the time. But regardless of what is reported to the phone, the battery still has the same capacity left in it. So the battery may have more life left in it than it reported there and it will continue to deplete slower or it may report it high and deplete it (seemingly) faster. I've seen several times too where if I let my phone idle for a bit, the percentage will actually rise (like it was charging, but it wasn't).
     
  4. jbdan

    jbdan Well-Known Member
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    Usually that happens when doing something in recovery (aka making a backup etc..). Did you spend any time in there?
     
  5. Sandroidfan

    Sandroidfan Well-Known Member
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    This happened to me last night first time like sudden 5% drop. It didn't reboot and looks like it happened after a phone call. It's weird... I guess it's a display bug.
     
  6. dhworph

    dhworph Well-Known Member
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    I've seen it jump both ways, but for me, most jumps have been upward, I've seen a 40% upward jump once... but usually they are small. seems to especially happen after reboots, not sure I've ever noticed one without a reboot.
     
  7. Tim K

    Tim K Well-Known Member
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    No, no recovery or anything....it just crashed and rebooted. Stock ROM (rooted but stock).

    Also, I've seen battery fluctuations after a reboot or battery pull, but its ALWAYS been an increase in % never a decrease. That's what I felt was so odd.
     
  8. truelove79

    truelove79 Well-Known Member
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    Wow, this is a coincidence. This just happened to me like an hour ago, except it jumped up like 25% (I had it plugged in and charging when I rebooted). I got on here to ask about it and I see that someone already has. Very strange.
     
  9. nj02vette

    nj02vette Well-Known Member
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    The battery never reports how much is left. The phone only monitors the battery voltage and takes a guess as to how much capacity is left based on battery profiles.

    Not directed at you, but there is a very common misconception that batteries tell devices how much juice is left. It's actually just a tuned guess as to how much capacity is remaining. There's lots of factors that I won't go into here, but it gets very complex.

    The drop in reporting may very well be the reboot, where the device has to run the screen, processor and memory at full capacity during the boot sequence. This drains the battery, or at least pulls the voltage down enough so the built in voltage curves guess there was a drop.
     
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  10. Sandroidfan

    Sandroidfan Well-Known Member
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    Very good points. But still it's weird that reboot alone will cause such a big drop like OP. Rebooting seems to cost about 1~2% on battery at most. And I also experienced sudden big jump on battery like +20% once when rebooted while recharging. I think battery reporting on ICS has some bug to be fixed.
     
  11. nj02vette

    nj02vette Well-Known Member
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    Yeah, I tend to think its more of a phantom reporting. Most likely the battery isn't dropping like that, just that it's being reported that way. Perhaps there's some hysterisis of the measurements that's causing the fluke.
     
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