How to change Offline Charging Animation ?

Hello everyone, i'm an OPO user but this thread could be interesting for all Android devices.

I saw that the offline charging animation of stock firmwares ( COS12.1 in my case ) is different from every other AOSP / CM based ROMS

Is there any way to change it? I can't find the location of thoses files..

Also is it possible to take another device's Offline charging animation and make it work on another device?

I found this in /res/images/charger/



But i found the same files on the Xperia Z1 running stock firmware. Thoses two PNG files must rely to something else , or may be used only when there is no OEM firmware on the device. Because this images look really similar to what i see when charging my OPO running a CM based ROM.