Thank You.
But for now I´am going for GPIO Controller to get the fully functions of your of the retro PSU boards.

but the tactile monument switch is connected to gnd and gpio 7....

Ok, Sorry! I try redefine my question: ".....Also included in this script is an on demand shutdown button script. If desired, a simple tact switch can be installed to GPIO 7. The script will monitor that GPIO in the background and invoke a safe shutdown when pressed...." (Mintybatterymonitor) I´ve i...

Thanks! also working here. But is it possible to leave the softshutdown button by the GPIO 9 pin running?

is it correct, the scriopt only works with GPIO controller wiring? So what to do to get the script running in combination with Arduino based controller pcb?

How must the Code be edited to work with a 3,7 V Lipo Battery?

no heatsink because it doesn´t help much... the hot air must out of the case, so a fan is necessary... under the Pi there an adafruit 1000c...
4000mah lipo... it fit´s without modifications .

I´ve this setup. Everthings running so far. But after 15 min of gaming (Mario cart N64) i´ve get an temp symbol top right in the screen.
So heat is a big problem. I´ve done some research of undervolting and underclocking the pi, but no success till yet...

PF21, can you please show me the arduino Code with analog stick settings?
Nice build, I will show next days my Pi3 Build here of course..

This area in retropie where wifi/raspiconfig/retropieconfig ...etc will be adjust..