For example I built a 0.32ohm coil on my velocity RDA I've been vaping it at 40-60W on my rx200, but I'm not sure if its safe to go any higher? Please could someone shine some light on this for me.
Safe in what regard? If you're worried about overstressing your batteries, then the resistance of your attached device is not a factor. 60 watts is 60 watts, and it demands the same amperage from your batteries regardless of whether you're pushing it through two ohms or two-tenths of an ohm. At a low-voltage cutoff of around 3.0 volts, using standard 20-amp batteries, you have a maximum of 60 watts per battery. You shouldn't take the RX200 up past 180 watts, and that's with
NO safety margin! If you want to use the full 200 watts, you'll need to use a 30-amp capable battery like the Sony VTC4 or the LG HB6. That will give you a nice safety margin even at 200 watts, well under the 30-amp limit of 90 watts per battery (270 watts per trio).
It is also extremely important that you use all three batteries of the same kind, purchased new, used together, charged together, never to be apart from each other. It is strongly recommended to get two sets of batteries and a stand-alone charger, as the RX200 is known for its less-than-stellar performance in balanced charging of the batteries internally. Label your batteries A1, A2, A3, B1, B2, B3 etc. so you know which ones go together. It's also a good idea to rotate their positions in the device and charger each time, just to ensure even wear across each battery in the set.
