if HRM-TRI battery drops to 2.90v it's about to fail (can be checked in FIT file)

brand new brand name Duracell 2032 replaced January 2021, failed April 2021, used hour per day, two on Sunday

so every 90 days or so just about, regardless of any claims by Garmin, 100 hours max safe use time between batteries

just like the HRM-PRO, the HRM-TRI saves the current voltage in the activity FIT file, they just refuse to show it in Garmin-Connect like the HRM-PRO to try to upsell you

but you can dump the file and check it yourself(I am going to write a utility to monitor it)

this was the file yesterday, failed today and lost the stored data during battery change because apparently the memory is not flash based but resets when power lost?

thanks Garmin :-(

device_info (23, type: 3, length: 94 bytes):
  manufacturer (2-1-UINT16): garmin (1)
  garmin_product (4-1-UINT16, original name: product): hrm_tri (1743)
  software_version (5-1-UINT16): 43.00 (4300)
  battery_voltage (10-1-UINT16): 2.90 V (743)
  device_index (0-1-UINT8): heart_rate (3)
  antplus_device_type (1-1-UINT8, original name: device_type): heart_rate (120)
  hardware_version (6-1-UINT8): 5
  battery_status (11-1-UINT8): ok (3)