The new "Hey Siri" feature in iOS 8 allows you to use Siri hand-free, but it only works when you're connected to a power supply. If you want to use it at other times, iDownloadBlog found a workaround so you can use it without being plugged in.
The workaround here is actually really easy to do and the end result is a hand-free Siri as long as you keep the screen from dimming.
- Enable "Hey Siri" in Settings > General > Siri
- Bring up Siri by holding the home button for a second and releasing.
- Don't say anything. Let Siri timeout.
- Say "Hey Siri" and your request.
Now, as long as the phone doesn't lock, you can say "Hey Siri" before any request and use it hands-free.
How to use "Hey Siri" without being connected to power [iDownloadBlog]