Hey, jmhucks.
I see that you feel the battery life of your iPad 2 has shortened since updating to iOS 11.3.1. I'm happy to help.
About the battery usage on your iPhone, iPad, and iPod touch -- Follow the steps in this article to determine which applications are using the most power, settings you can adjust to improve the battery life, and using Low Power Mode to extend your battery life.
iPad Service and Repair -- If you feel that your battery isn't working correctly, you can use this link to set up service and repair.
Take care!