https://www.theverge.com/circuitbreaker/2017/9/20/16335670/echo-dot-google-home-battery-bases-portable-ninety7

The accessory company Ninety7 is continuing its quest to untether smart speakers from wall outlets with the introduction of new battery packs designed for the Echo Dot and Google Home.

First up is the Dox, which will sell for $39.95 (but is launching on sale for $29.95) and adds a rechargeable battery to the Dot that’s supposed to let Amazon’s tiny speaker run on its own for 10 hours. The downside is that slipping the Dot into the Dox increases its size substantially — the whole thing is about double the height and almost half an inch thicker too. I’m also not entirely sure what you’d use this for, since the Dot isn’t exactly stellar as a music speaker, and you could buy a better Bluetooth speaker for $40.