Well, mine allowed me to adjust all the way to 200w. But when I tried pressing the fire button it read "batter weak". I assume because my charge is low. Tried 173, 130, same result.
Weird issue though. When I first put my batteries in the mod after charging them in an external charger for the first time, each of the batteries gave a different voltage reading when I turned the mod off, and held down all three buttons. Even though I hadn't fired the mod yet.
The rx200 does that when you check batteries. What firmware does it have?
A DMM is the best way to check them.
The more power you're running, the sooner the mod will cut you off. My Sig 150tc cut me off last night with 3.71v left on the batteries only running 75W. Either its being particularly cautious or it may be time to get some more new batteries and break that pair up for single coil mods.