Digital Matter Support

Yabby Cellular Battery Capacity Estimate

It is useful to estimate the remaining capacity of the Yabby Cellular batteries. The nature of the Lithium AAA batteries (LiFeS2) recommended for the Yabby requires a capacity estimate to be made based on sampling the battery voltage after at least 3 hours at a low current. The Yabby attempts to sample the battery voltage at a low current, and the highest recent sample is stored in Analogue 1. This can be used to make some rough estimations of the remaining capacity.


GPS Firmware 2.10 / 3.10 and WiFi Firmware 2.4 / 3.4, and higher


Voltage Range
Capacity Estimate
VBatt Good Status Flag
4.85 – 5.30 V
50% + remaining
Set (1)
4.20 – 4.85 V
0 – 50% remaining
Clear (0)


Earlier Firmware Versions


Voltage Range
Capacity Estimate
VBatt Good Status Flag
4.80 – 5.30 V
40% + remaining
Set (1)
4.65 – 4.80 V
25 – 40 % remaining
Set (1)
4.50 – 4.65 V
10 – 25% remaining
Clear (0)
4.20 – 4.50 V
0 – 10% remaining
Clear (0)


Notes

  • These groups do not imply a linear relationship in each range. The voltages can only be used for rough classification into one of the given ranges.
  • More accurate estimations are not possible without a fuel gauge (available in next generation Yabby and Oyster 2), because of the battery chemistry.
  • This will be less accurate if the device does not regularly sleep for 3 hours. For example, hourly heartbeats may not allow the battery voltage to recover completely, leading to a lower estimate.
  • Further to the previous point, the voltage will not recover completely if the device is usually colder than 5 degrees C. The low temperature stops the battery voltage from recovering completely, providing a lower capacity estimate.
  • Analogue 5 (Loaded Voltage) is an instantaneous sample of the battery voltage, and varies considerably with device activity. This is not useful for battery capacity estimates.


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