I’ve found that the more graphic intensive processes you have in your game, the hotter the battery gets.
Try using mainly unlit materials.
Don’t use a dynamic light, make it static.
Look at Shader Complexity and make sure it’s as dark red as possible. If you see pink/white, that is really bad, especially on a mobile.
How many particles are you using? Are they unlit?
How much are you rendering? Are your draw calls really high?
I struggled to keep my game running at 60fps because my phone kept overheating (S6) and dropping down to 50-45 until I did the above. Also, make sure you’re testing in Shipping and not in test. You can’t bring up your FPS counter, but you can usually tell if it drops below 60. This runs without any of the debugging features and generally runs faster.