Connecting Ipega 9037 via usb otg to smatphone I have problem with my device while pairing my controller.The joysticks are working and also the dpad, but I have think that can I use this controller over usb otg, does it damage the smartphone battery.
If you are linking it trough the cable and not Bluetooth, it won't drain much more battery than pressing the volume buttons.

In other words, nothing you'll ever notice.