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27.09 Battery drain reproducible problem proof and battery graphs.

chocorello

I am reporting proof of a reproducible battery drain issue on my Forerunner 255 after updating to software version 27.09.

Device / Software Versions:

  • Software: 27.09

  • GPS: 13.00

  • WiFi: 28.27

  • CIQ: 5.2.0

  • BMX: 21.1.0

Issue Description:

After completing an “Indoor Bike” activity (~25 minutes), the battery discharge rate becomes significantly higher than normal.

Key observations:

  1. The increased drain begins immediately after ending the Indoor Bike activity.

  2. Restarting the watch via the menu does NOT resolve the issue.

  3. Performing a forced reboot (holding the Light button until shutdown) restores the normal discharge rate.

  4. The issue is reproducible.

  5. At the moment, Indoor Bike is the only activity I am using (due to injury), so I cannot confirm if other activity types trigger the same behavior.

I have attached screenshots from the “Battery Graph” Connect IQ application:

  • Yellow circle: 25-minute Indoor Bike activity.

  • After activity: noticeably steeper discharge slope.

  • Red circle: forced reboot.

  • After reboot: discharge slope returns to normal.


The behavior strongly suggests that something remains active after the Indoor Bike activity ends, causing excessive battery consumption until a hard reboot is performed.

Please let me know if logs or additional diagnostics are required.
I would also appreciate instructions on reverting to the previous firmware version if possible.

please note:
the watch does not run any other iq-connect apps than "battery graph" which was installed after the problem occurred.
No wifi active at any time before or during the problem, nor Bluetooth.
Also no connection to sensors, straps or any peripheral device.

Just a standard 255 - thanks.


  • 0

    What if you peek under your watch, and look at the heart rate sensors, are they blinking or constantly on? 

  • 0

    Hello, I have the same issue. I confirm the battery drains quickly after finishing an indoor activity – cycling with my whoosh + Wahoo Kickr Core. I have a trainer and a HRM PRO chest strap paired with the watch. After syncing, the battery starts draining rapidly. As advised in another topic, forced shutdown of the watch by long pressing the LIGHT button helped. Afterwards, the battery drain returned to normal. I do not see this battery drain issue after syncing other activities like running or hiking.

  • 0

    An update for the tech guys.
    Yesterday I did "treadmill running" for 20' and today "indoor bike" for 30'. (rehab is going fine - thank you :-) )
    You can notice that while the green circle of treadmill running did not cause an accelerated discharge rate, the red circle of indoor bike caused a steepest angle/rate of discharge until i rebooted as mentioned at the yellow circle.

    To be clear: in my case the problem appears on "indoor bike" and not "treadmill running". Hope it helps.


    Please          or anyone else, respond to your customers and users.

    again: Please let me know if logs or additional diagnostics are required.