HomePod mini update makes it usable with 18W power supplies

A new update for the HomePod (version 14.3) will allow the HomePod mini to run on 18W adapters or battery packs. The speaker ships with a 20W power adapter, and it initially needed at least 20W to work. But this update reduces the limit to 18W, allowing it to support a broader range of adapters and battery packs. It also means you can turn the HomePod mini into a portable AirPlay 2 speaker of sorts, as long as you have a proper Wi-Fi signal.

Apple hasn't announced this feature in its update notes. Reddit users discovered the change when it tested the speaker out with different power bricks. 

Source: Apple Insider