Just curious what the best resistance coil to use for a specific voltage? Any charts out there? I'm using ego style batteries with my EVOD tanks, not really having a problem but just curious what people use or what would be considered optimum. 2 of my batteries show 3.9 volts through most of their use, and I have a twist that I just set at 4 volts. I've been using 2.2 or 2.5 ohm coils.