What exactly does "Wipe Battery Stats" do?

Discussion in 'Android Tech Support' started by Jaxidian, Feb 1, 2011.

  1. Jaxidian
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    Jaxidian Team FreeMyMoto Premium Member Developer

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    So we all know (or should know) that when we have a battery die and replace it, we should "recalibrate" the new one, which involves wiping battery stats and a full drain from 100% to dead, and the like. We also know that this is a useful tool when upgrading from a 1500mAh to 1900mAh battery, and the like. We even know that when we flash a new ROM that we should wipe stats so the new ROM (which will handle the battery slightly different from low-level tweaks) will be more battery-efficient.

    All that said, it's very unclear to me (and some quick googling failed in helping provide additional information) as to what exactly wiping battery stats changes, and even where. The questions that I would love to have solid answers to:
    1. Where do battery stats exist? In the phone or in some memory chip in the battery itself?
    2. Are battery stats battery-dependent?
    3. If stored in the phone, where at? (Specifically wanting to know if installing a new ROM that formats /system/ will wipe them by the format or is it somewhere else?)
    4. If I have "calibrated" a 1500mAh battery and a 2000mAh battery, do I need to wipe stats when I switch back and forth between the two?
    5. If I have "calibrated" two different identical 1500mAh batteries, do I need to wipe stats when I swap back and forth between the two?

    Just looking for more understanding around what's happening behind the scenes here.
  2. hookbill
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    hookbill Premium Member Premium Member

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    Man, who told you all this nonsense? None of that is true, you don't calibrate a lithium battery. That's just crazy.
  3. Jaxidian
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    Jaxidian Team FreeMyMoto Premium Member Developer

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    Yes, and no. It's not the lithium battery that you're calibrating, it's something Android-specific that you're calibrating. It's essentially software that you're calibrating to make sure it understands a battery properly. This is why I used calibrate in quotes. The memory effect that our phones' batteries have is NOT because of the lithium technology but is because of Android-specific technology. It's that technology that I'm trying to understand.
    Last edited: Feb 1, 2011
  4. hookbill
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    hookbill Premium Member Premium Member

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    Oh…..I gotcha now. So you're trying to improve upon the technology of the software to extend the battery life. Interesting.

    I've been of the opinion that if that could have been done it would have been done a long time ago. By Google. I really don't see too much difference in battery life between my D2 and my old Blackberry Storm, both sucked up battery like there was no tomorrow. But hey, I'm not that technical so maybe you're on to something.
  5. Jaxidian
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    Jaxidian Team FreeMyMoto Premium Member Developer

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    Well, you kinda got me. You now understand what I mean by "recalibration". This already exists in Android, by Google or the manufacturers - I'm not trying to make any improvements to it to extend battery life.

    What I'm trying to do is understand the pros/cons of running with multiple batteries and charging them via external chargers. I've seen some interesting things in my experiments and I'm trying to make sense of the results. For example, I let my phone die with a 1500mAh battery in it and when I put a battery that I thought was 100% charged in, it displayed 5%. This would indicate that Android isn't really taking metrics from the batter itself but is simply just trying to predict its capacity. However, I used to do this all the time with my G1 and with it, when battery A died, putting in fully-charged Battery B showed 100% as soon as I booted up with it.

    So I'm trying to learn what Android is doing, or attempting to do, with its battery stats. What stats does it keep (don't care too much about that), how does it tie stats to a specific battery (is VERY important), and how I can tell it to ignore its predictions because I really did just put in a fully-charged battery.
  6. Tanknspank
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    Tanknspank Beta Team Premium Member

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    The batt stats is a file under data, and it attempts to keep a good record of your usage to accurately predict your battery use. It's good to wipe this, if you're able, every two weeks or so. This file can also get messed up if you flash a rom on a non full battery, hence why battery can be worse after flashing a new rom.

    Sent from my Droid using Tapatalk
  7. UltraDroid
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    UltraDroid DF Super Moderator Staff Member

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    Tank, *where* under data do I look for the battery stats - what's it called? :)

    -Mike
  8. Jaxidian
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    Jaxidian Team FreeMyMoto Premium Member Developer

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    Do you know if the stats are specific to an individual battery or are they generalized for any battery that you insert?
  9. Tanknspank
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    Tanknspank Beta Team Premium Member

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    It is the batterystats.bin under /data/system.
    It will be sorta specific to a battery, from what I can tell. I swap batteries semi often, so it isn't going to be totally specific, but if one is new, and the other is older, your phone might not be able to tell the difference.

    Overall though, it is probably more generalized.
  10. UltraDroid
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    UltraDroid DF Super Moderator Staff Member

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    Thank you sir! :)

    -Mike
  11. nornevrder
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    nornevrder New Member

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    This is some good info thanks. Howdo ypi wipe the battle stat file. Just delete?

    Sent from my Droid using DroidForums App
  12. BayouFlyFisher
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    BayouFlyFisher Rescue Squad Rescue Squad

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    I'm under the impression that it's just a log file used by the system to try and help with the battery percentage calculations. Delete it and a new one will be started.
  13. brando56894
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    brando56894 New Member

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    You can do that but theres also the option in clockwork mod.
  14. nornevrder
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    nornevrder New Member

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    After wipe and recharge do I let it drain completely till it dies?

    Sent from my Droid using DroidForums App
  15. Threeball
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    Threeball New Member

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  16. whteglve
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    whteglve New Member

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    I must be stupid but I can't find the batterystats.bin file. I have an empty data folder too.
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