Re: Battery size for VarroVap?
I don't know how you used the device, of course, but if there was power applied to the vaporizer after the oxalic acid was already vaporized, the unit will get hotter than it was when actually vaporizing, and that could lead to damaging the wire covering.
The process of boiling off the oxalic acid has the effect of cooling the device, and once the acid is gone, so is the cooling effect.
(I have an electric egg steamer/boiler and the same effect happens there. While the few tablespoons of water is boiling and making steam, the temperature of the device water pan is more or less 212 degrees F. It can't go higher until all the water is turned to steam, and once that happens the device detects that higher pan temperature and sets off a "Done" buzzer.)
USDA Zone 7A Elevation 1400 ft