Troubleshooting guide for high battery drain

In brief: Complete/verify the update with Garmin Express, reset the watch, and go through the full charging cycle (twice).

That advice works in the vast majority of cases of a sudden high battery drain after a firmware update, that we use to see here on the forum frequently. If it is not your case, if it does not help, or if you need more details, please continue reading:

Possible Reasons of High Battery Drain

  • Do this first of all in every case: Incomplete firmware update - firmware updates often come in several parts, and if the updating of some of the parts fails, it may lead to unpredictable behavior of the watch. Connect the watch over the USB cable to a computer with Garmin Express, make more free room on the watch (explained below), open the panel with the concerned watch, click the symbol ⟳, and install any pending updates. 

  • The battery gauge is decalibrated. Fully charge the watch and leave it plugged in for an hour more, after it shows 100%. Then disconnect, sync, and perform the reset (hold the Light button for up to 30s till the watch shuts down, keep holding the button through the emergency notification if any comes). No worry - no data, and no settings get lost, at the reset (unlike at the master reset to factory defaults)! When powered down, wait ~10s, and restart. Use the watch until it fully discharges and shuts down. This process should recalibrate the battery gauge. In some cases you may need to repeat the full charge and full discharge cycle twice, in order to reestablish the calibration.

  • You use excessively power-hungry options such as the PulseOx, GPS, or backlight - verify the settings and disable especially the nightly and all-day PulseOx options
  • You use a power hungry Connect IQ app or watchface. Uninstall all CIQ apps, to see whether it helps
  • There is an excessive usage of the Bluetooth connection. That can happen for example when the watch continuously tries to download an update, and it goes on failing each time (i.e. due to low storage, communication problems, etc.). There are many other possible reasons though too (failed sync attempts, syncing huge segments, maps, ...). To confirm or exclude BT as the culprit, disable the BT ('Phone' option in the Controls menu) for a few days, to see whether it makes any difference
  • If nothing of the above helps, then the next step is the master reset to factory defaults, as the last resort.  
  • There is a hardware problem - if the master reset did not help, then the watch may be defective, and needs to be replaced. Contact the Product Support.

How to Avoid Battery Drain Issues After a Firmware Update

  • Disable automated updates in the settings
  • Watch the forum for new firmware announcements (typically at the end of each quarter)
  • When new firmware is available, and fully rolled out, connect your watch over the USB cable to a computer, and prepare the watch for the update - the process requires a significant amount of free space. If there is not enough free room on the storage of the watch, then the update may finish in an infinite loop draining the battery fast. You can remove all files from the folders //GARMIN/RemoteSW/, //GARMIN/Activity/, //GARMIN/Debug/, and unused fiels from //GARMIN/Text/, //GARMIN/Courses/, //GARMIN/Workouts/.
  • When the update is ready, and the storage cleaned, check for updates with Garmin Express
  • Let the watch charge to 100%, and wait a few minutes more before disconnecting the cable
  • Disconnect and let the watch do the firmware update
  • Reconnect and check for updates with GE again, to see whether the new firmware needs to download additional elements
  • Disconnect and do the reset (hold the Light button for ~30s till the watch shuts down, then restart)
  • Use the watch several days or weeks till a very low battery level, then fully recharge - that will re-calibrate the battery gauge in case the calibration was misaligned during the update

The rationale behind it is, that the OTA firmware updates are problematic, slow, and I suspect that they can even lead to a bricked watch, for example when the loading of an additional Sensor Hub firmware fails (occasionally, we see such cases on the forum). The download speed for the OTA update is intentionally throttled seriously, and it may take several hours or days to download the firmware. And when some additional components (SNS, GPS, languages, maps, zone tables,...) need to be installed, after the main firmware is in place, it may indeed lead to a prolonged downloading attempts in the next few days.

Besides that, the watch may malfunction, if all components are not updated to the latest matching versions in the same time. The installation of additional components may also fail if there is insufficient storage (especially a problem at watches with small memory, such as Instinct).

The next problem is, when the OTA update happens unattended in the night with a depleted battery. In the worst case it can theoretically lead to a bricked watch, if the battery dies in the middle of the upgrade. Depleted or a half charged battery may also lead to a decalibration of the battery gauge, which then reports wrong levels, and rapid discharging rates despite that the reality is often (though not always) all right.

Following the steps described above, should prevent all of this. I do always my updates in this way, and I do also install all available beta versions since many years on several Garmin models (hence having already done certainly over a hundred of firmware updates), and I never experienced any battery drain problems after an update.

  • Important note about the battery gauge calibration:

    The battery has the max voltage when fully charged, and the min voltage, when discharged (or when the watch shuts down). The battery indicator of the watch then measures the actual current battery voltage in real-time, compares it to the min and max values, and shows then the level according to their ratio. When the last acquired min and max values are lost during the firmware upgrade, default values are used instead, and hence the watch then shows incorrect level values. In most cases it shows discharging rates much faster than they really are.

    In these case, the true min and max values need to be measured anew to reestablish the accuracy of the battery indicator. In order to measure the max value, you have to charge the watch fully. But since the battery gauge, due to the decalibration, may be showing 100% charge when it is not at all fully charged, it is very important to let the watch attached to the charger for certain time after it starts showing the 100% charge! In the OP I recommend charging it around an hour longer. Only when the battery is truly charged to the max, the max voltage can be measured, and the calibration reestablished.

    Yes, overcharging the battery is not very good for its health. However, first of all, you are actually not overcharging the battery, because in fact in these cases, it is not fully charged when the indicator starts showing 100%. And then, such occasional event cannot have any noticeable impact on the battery, even if the battery was overcharged for a while. And if you follow the instructions in the 2nd part of the OP, then you can avoid these high-drain events entirely.

    Similarly, you have to keep using the watch till it shuts down, to reestablish the bottom voltage limit. Again, an occasional event like this, won't damage the battery, since the electronics shuts down before the voltage of the battery gets critically low.

    Once the battery gauge is calibrated properly (often after the first full charging, sometimes two cycles are needed), you can go on charging in the way you are used to. Some people prefer charging only up to 80% to preserve the battery. Just remember to charge to 100% when doing the next firmware upgrade. As written in the OP, I highly recommend always updating the firmware over the USB cable from Garmin Express!

  • Are you able to force a reinstall with Garmin Express if you are already running the latest firmware?

  • Not with Garmin Express, but some models allow doing it from the Developer Menu of the watch. More details for example here: https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/362033/fenix-7-heart-rate-not-detected/1738873#1738873 

  • Some more tips copied from the thread https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct-2-series/386137/16-11-instinct-2-solar-battery-drain-issue/1840736#1840736 

    Assuming that BT is the reason for the battery drain, the problem would be identified, but how would the fixing occur?

    As advised in the OP, the first thing to do before anything else, is connecting the watch over the USB cable to a computer with Garmin Express and checking for updates with it. You may even try it another time after disconnecting and reconnecting, to be sure no other additional updates are still pending.

    Pending updates may consume a lot of power, especially if the BT and Wi-Fi channels are close to each other, and/or the phone does not have a good separation filters. BT and Wi-Fi use the same frequency band. Especially Samsung Galaxy S2* models, and then plenty of low-cost Android phones suffer from it. So another possibility to fix high drain caused by BT, is switching the Wi-Fi on your phone from the 2.4 MHz band to the 5 GHz mode (as long as the phone and the Wi-Fi AP support it). Another option is resetting the network (Wi-Fi and BT) in Android's settings - it may help redistributing the channels slightly farther away from each other, which may help.

    Then, you should make sure there is always only a single device paired with the watch in the proximity. If you paired it with multiple devices (phone, tablets, computers), there will be interferences, and again it will lead to slow transmissions, and to increased power consumption.

    Then you can observe when the drain is the highest. If it is for example during the night, then perhaps the watch tries to connect to the phone that is farther away, somewhere on the limit of its range, and again it pushes the watch to increase the transmission power, and do repeated attempts.