How can I check battery health on 4S?

I have an older iPhone 4s. It appears lately to need to be running down like its being drained more, but few if any apps running. I try to turn off wifi when not at home so it won't try to connect to ones I can't use. But the battery I'm sure could be just petering out. How can I check to see how healthy it is? I am running iOS 9.3.5. I don't run Location Services for ex. But mostly asking how can I see how many times it's been charged, or is there a good free or paid app that will tell me its health? May look to buying new phone 5 or higher at some point but can't yet.