Just wondering how many people run two packs in series with the speed pinion. I did it one time when I first got my Rally and after about five minutes my car shut down, my batteries were smoking and the ESC was fried. I just got back a new ESC from Traxxas and am scared to do it again. Im thinking it was a faulty ESC or battery because it was only a few minutes of running. Is it safe to run in series?