Hello
I've had issue yesterday about connecting a PS3 wireless controller, I found the tips on RecalBox's forum, and it's also working on Batocera.
First of all, you need to reset your PS3 Controller by pushing the button beside the controller.
After, take a USB cable (not a charging but you need a data cable) and connect it to your USB port, when it's connected, wait for 10/15 seconds, then disconnect the cable, the wireless connection should work then.
If you wanna try, reboot the Batocera and when it's on and you're on ES, click on the PS button in the middle, should connect instantaly.