For some reason, Pali decided, that bq27x00_battery doesn't export some (full charge, current charge) *at all*, when "need calibration" (more than 32 cycles since last calibration, or never calibrated) flag is present - no matter if calibration data were lost, or not.

It's very irritating, to be honest, as every 32 charging cycles you need to re-calibrate battery, as you get 0/0 mAh readings from battery applet (despite fact, that bq27x00 hardware still have pretty correct calibration data).
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Sticking more precisely to your question, removing battery for too long + having "clock battery" dead (itms the case for 90% of devices), may result in bq27x00 losing calibration data + setting flag "need calibration" to 1.

/Estel