My old battery was so worn out that I got a 1600 mAh replacement.

I charged my battery on Thursday in the late evening. bnf reported that VDQ = 1.

I was mildly using the phone during the next day, checking e-mail, browsing the net, calling - nothing unusual.
IIRC when I went to bed yesterday, it was still VDQ=1, voltage V ~= 3400 mV.

Today I woke up, VDQ=0, voltage V ~= 3300 mV. After a while BME decided the battery is almost dead and the deviced turned off.

Why did VDQ turn to 0 when the device was idle? Can I do something to calibrate my battery?