If your cadence sensor is draining batteries very quickly, a couple of things to check:
Ensure the battery is not a 50cent cheapie from the dollar and dime store. These will maybe give you an hour or two ... and then fail. This is a known fact.
Update the firmware in the cadence sensor.
The update is completed by installing and using Wahoo UTILITY for this (updating) purpose ONLY
Once the update of your Wahoo device/sensor is completed, UNINSTALL Wahoo Utility. It can be reinstalled anytime ... if you do not uninstall it, you risk data loss.
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