[Q] Battery Overcharging Concern topic

Hi,

I recently bought the 2GB RAM variant of the ASUS ZenFone 2 (ZE551ML). I noticed that if the phone was kept on charge for an extended period of time, after the battery had reached 100%, it would take an exorbitant amount of time to go from 100% to 99% and would discharge normally after. During this period the battery section under settings would not report any usage statistics either.

However, if I disconnect it before it hits 100, I noticed that the rate of discharge is how it should be.

If I leave it connected to the charger after it hits 100, CPU-Z reports a battery voltage of 4278mV and once I disconnect it starts discharging from 4227mV. I read somewhere that 4.2V is the max safe limit for a Li-Po battery.

I'm concerned if any of this is an indication of the battery getting overcharged. Any inputs would be appreciated.

Thanks.