I've been using the Smith Turbos for years. I don't know how many different types of crap I put on my goggle lenses to prevent or even reduce fogging, but nothing was ever good enough... until I found Smith Turbos.
The design has improved over the years and the initial issues have been resolved. The battery pack is minimal (holds one AAA battery), stays out of the way, and is sealed. The fan noise is almost imperceptible.
I've been out of the wettest and snowiest days and as long as I can keep my wipeouts from filling my goggles with snow, they stay fog free.