Q: i have iphone 6s  9.1 battery percentage stopped working

Greetings buli1111,

Thanks for using the Apple Support Communities!

From your question, I understand that the battery percentage on your iPhone isn’t working as expected. To troubleshoot this situation, I would suggest starting with some basic troubleshooting. 

I would first suggest toggling the battery percentage off and on. You can find instructions for navigating to this setting in the following article. 

Show the battery percentage on your iPhone or iPad - Apple Support

If you continue to have an issue with the battery percentage not displaying correctly, I would suggest restarting your iPhone as described in the next article. 

Restart your iPhone, iPad, or iPod touch - Apple Support

Have a great day!