Problem with charger IC

[hcglitte]

Hello,

I am using bq24272 in my project. The lithium polymer battery is specified to 4.2 V 2500 mAh.
CC is set to 0.2C = 500 mA.
I am setting the registers to enter CV phase @ 4.2 V. The termination is set to 0.02 C = 50 mA.
After a while (sometimes) the IC will detect that the battery
has a too high battery voltage, called battery OVP (overvoltage protection) and it will start to drain the battery as a safety precaution.
The battery will then be drained too much (this I will still need to verify with a current logger).
I am trying to figure out a way to cancel the charging if that fail occurs - assuming that it has reached maximum charge.

Anyway, does anyone know why the battery will reach a higher voltage? I mean, the IC is supposed to decrease the current in order to keep the voltage at 4.2 V.
I may have to write some code to check if it reached "charge done" before it enters the Batt OVP - so I don't need to lock at the LCD for 6 hours etc...
But I can't imagine that the battery voltage will increase after the DONE state (since then no current is flowing into the battery).

Any input is appreciated.