Bangle.js 2 - Battery always 100%

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  • Ok, it's possible you may get a slightly better fit by running the code while the watch is still on the charger?

    But I think probably once it gets down to 10% you need to be thinking about getting it on charge anyway. While it might last a few days longer I imagine it could turn off pretty much any time if there was a high power draw (eg GPS)

  • I have upgraded Gadgetbridge today to 0.66 and finally the battery history just fixed there.
    With that I could confirm my feeling, that the charge level display seems a bit "flaky".
    Could this be somehow in connection with the algorithm change that was discussed above?

    Firmware on my Bangle2 is 2v12.93.

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    • Screenshot_20220324-195248.jpg
  • The charge level reflects the voltage measured by the Bangle. This voltage will vary according to the current drawn by the Bangle.

    The voltage of the battery, measured by the Bangle, will vary according to load on the battery. Batteries have internal resistance so the voltage seen by the Bangle will decrease as the current drawn increases, according to Ohm's Law. So, the voltage will go up and down as you turn on and off various things such as GPS.

  • On another thread somebody suggested reporting minimum voltages while discharging and maximum voltages while charging. That would greatly reduce those fluctuations seen under different loads. It would also better match the average persons expectations that the battery should never go up while not charging and never down while charging.

  • Yes, temperature has an effect as well as the current load (eg if screen is on or off).

    Yes, we could add some kind of filtering on battery level, it's just whether in the scheme of things this is that big a deal. It can cause other problems too - maybe you turn GPS on and then suddenly your battery appears to have instantly lost 5% charge - and I wonder whether we'd see threads about that too.

  • It might be best to just stick with

    battery level can be a bit erratic, as it depends on both temperature and current load

    Filtering will never be perfect, and then you end up having to explain it anyway, except now complicated by the filtering.

    And GadgetBridge could be a bit smarter about the battery level warnings, i.e. wait for the battery level to go above 40%, or the charger to be connected, before resetting the warning.

  • Yesterday, my watch crashed, but had the backlight on. Within 90 minutes (the old time was frozen on the display), the battery was fom 60 to 10%.
    I had to hard reset it. I hope it won't happen again.

  • @gfric if it happens again, as a first port of call I'd switch to using the default set of apps. Since you're doing quite a lot of development work by the look of it, there could be a bug in some of the code on the Bangle.

    I guess the obvious one would be a memory leak...

  • I set gadgetbridge to notify me when the battery drops below 30%. Howver, the watch reports non monotonious values like 32..29..31..28, so GB notifies me like mad.
    Can't we remember and report the lowest measured value unless the watch was charged to fix this? I had to turn bluetooth off, because I was far from the charger.

  • @gfric You can turn off the low battery notification in the Android notification settings for Gadgetbridge. So you won't have to turn off Bluetooth...

    That suggestion sounds like a good idea though, but it might be on the radar already since I'm pretty sure I've seen this brought up before. Or maybe I'm misremembering.

  • Yes, there was some discussion about this before, but it was decided that actually messing with the reported battery value might cause more problems (like "why did my battery drop by 5% when I enabled GPS and then not move for 6 hours").

    I'd be totally up for adding this filtering to either Gadgetbridge, or to the 'Android Integration' app though?

  • Yes. Just report it filtered to gadgetbridge. Apps must be able to query the true value.

  • I've just added calibration to Settings so in a day or so you'll be able to go to Settings -> Utils -> Calibrate battery when the Bangle has been on charge and it'll reset the battery percentage meter

  • Hi Gordon,
    a while ago I mentioned my watch's battery doesn't alter - it always shows 100%. I have waited to allow time to see whether updates may fix this issue.
    As the situation hasn't changed, is there anything more that can be done?

  • @user140458 if you're on version 2v13, install the latest settings from the development app loader at, put the Bangle on charge for a few ours so you're very sure it's full, then do Settings -> Utils -> Calibrate battery

    The functionality's been available for a while but I only just added an easy option to the default settings app

  • Cheers, charging up now and will try it out tonight

  • Hi Gordon,
    the battery indicator is now recording change (overnight it recorded that it lost about 2% and during today it has very steadily and slightly reduced).
    So, it's all looking good!
    Thank you very much, as the only niggling issue was not knowing when it was going to lose power completely.
    Many thanks :)

  • Great, glad that solved it for you!

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Bangle.js 2 - Battery always 100%

Posted by Avatar for user138058 @user138058