I had left my wired obd reader plugged in a few times in the garage and noted that my battery was weak when not on the tender. I was at a cars and coffee Saturday and had a non start battery. I had been messing with the fog light and parking light switches at the event and had left the parking lights on so mostly attributed it to them. I just got a wifi OBD device and it was in the car as well and I thought it could have contributed also. Sitting in my family room just now next to the garage my phone won't load Internet pages. It had. Switched to the wifi from the obd. So, wifi or wired, the obd readers draw current when the car is off. Just a heads up
