At the moment i have one problem. Since tablet is very smart, it can track how much power does on-board battery charger put into battery, and how it used, it can calculate that it is running out of power. Problem is i have constant 2A CCCV power supply that feeds power directly to battery contacts, even if voltage is at perfect 4.2V, Lenovo Phab plus can still say it is getting low on power and will shut down !
If any one is interested to have same navigation system for your car, and can provide me with help regarding adnroid developing, I.E disable power supply cheking for restarting, since then car is turned on, 4.2V 2A power supply should keep this navigation alive forever. But right now it is not.
This navigation system is rooted, but i am hardware engineer, not software, so this is where i need your help ! I could provide all pcb boards for this project, since i have more than 3 copies made, and used only single one :)