"The nano peaks @ 25 with a max continuous load of 17.5"
Those would be 25 watts and 17.5 watts, respectively. Just my personal guidelines, I usually up-size on such things as converters since I "just know" there will come a time when I'm going to need bigger. My car's 12 volt system is run through a nice step-up converter that outputs 400 watts at 120 volts, enough to power my e-Nano, my smartphone and iPod.