Operating your Echo 2 on battery power allows you to take the smart speaker with you into any room in your home or even into the yard if your Wi-Fi network is strong enough to reach there. That’s a much less expensive alternative to putting an Echo in every room for smart home control, or investing in a multi-room audio system so you can listen to music everywhere. You can also take a battery-powered Echo 2 on picnics and camping trips if you create a mobile hotspot with your smartphone. Ninety7 says you can expect to get eight hours of battery life, a claim I didn’t attempt to validate, but continuously playing music on the speaker is likely to reduce that time.