Make device take power only from charger when the battery is full I made a device that is up and running (screen is on) 24/7 and connected to AC charger. After only 1 year, the batteries of these devices are dead. I don't really understand since the device is directly connected to AC, the battery should be bypassed and never been used.

I made some current measurements and I discovered that the current consumed by the device is sometimes 0 for ~1 minute. So it is obvious that the battery is working because if AC current is 0 while the screen is on, it means the battery is working. 

This power management does not make any sense. Is it the expected one? Is there any hack I can do using ADB commands?

thanks
"I don't really understand since the device is directly connected to AC, the battery should be bypassed and never been used.

If you mean li-ion battery, cycle use is recommended
since keeping it fully charged for 24/365 may shorten its life cycle as in your case.

Since you need battery as backup only, use UPS (Pb  gel battery) coming with bypass instead