Interesting Discharge Curve

 

The PecanPico3 tracker has been running for more than 24 hours (actually more than 27). It’s interesting to observe the telemetry records at aprs.fi. The 3.6V 400 mAh NiCd battery was discharging slowly through the TPS61201 regulator and kept an almost constant 3.6 V for 20 hours.  Then suddenly the regulator switched from buck to boost mode and the measured battery voltage dropped rapidly to 2.4 V. It went back to buck mode for a single cycle but didn’t stay there for the rest of the operation until it stopped transmitting.

DischargeCurve