Yes, I had it on a charger. Interesting idea about having the door closed with the window down while flashing. I did it with the door open and window up. I had a scary result on my first flash attempt so I wanted folks to know what worked for me in the end. That is a good suggestion about allowing a day or two just in case of a problem. I have also been very happy with Eurocharged so far. Best of luck with the sprint booster and exhaust.