5s Battery drain

[Jefferyd32]

I have a 5s that I use and charge daily. I've had since shortly after launch and always charged the battery daily. I don't use it a ton and until recently battery power was close to 50% each night, but the last week or more it has been consistently down to 20% or less with the same usage.

Anyone else having such issues or did an update cause things to go haywire? I still have until fall before I will upgrade and this battery life will not get me through summer.