Zumo User Forums

On a few occasions I've tried the WIFI update, just out of curiosity, I always got a warning that a power supply was needed. So I had to plug in the USB anyway. (Or mount it on the bike, but that would be even more work)

Or plug it into a wall charger?

Sure that works too.
But the WI in WIFI stands for Wireless (not native English, but that's how I always understood it). Having to plug in anything is contradictory with Wireless.
It's not a big deal, I prefer the cable when updating. It just doesn't make sense to me.

Yes but little point in trying to update over wifi if battery fails half way through. You can be anywhere and update over wifi so you're not tied to a computer of any type. Bit like browsing the web over wifi, you don't want your phone battery to die while doing that either. WiFi simply allows you to connect wirelessly to a network, doesn't mean you don't need power.

When I’m home, with strong WiFi and a fast connection, no problem. But on the road I have found many hotels and restaurants have either weak WiFi, slow, or both, which could really mess things up, so be careful.

-dan