Why my Iphone only respond to me on hey siri if my phone id attached on charger

As Chris noted, if you have an iPhone 6/6+ or earlier, "Hey, Siri..." will only work when it's plugged into a power source.

You can sort of get around this by carrying a rechargeable battery pack in your pocket and connecting the phone to it.

What version of iPhone do you have? Some of the older phones were required to be connected to power to get Hey Siri to work.

Did you follow the troubleshooting steps in the Related Article in your post?

Thank you for handling that. I'm gone on Wednesday nights, so I wasn't around to respond after my last response.

Oh, I can't resist answering some questions! ;-)