battery draining overnight with no apps running

There is never a time when nothing is running on an iPhone. And putting it in Airplane mode can actually increase battery drain as functions try to access data and fail. And there is no way to make sure that no apps are running; killing apps just removes them from the list of used apps, it doesn’t stop them from scheduled runs.

How much energy is it losing overnight, and what is your battery health: Settings/Battery/Battery Health. And is this an SE or an SE 2nd edition?

You are doing it backwards. you should be charging overnight, every night, with Optimized Charging and Automatic Backup enabled. If you do that you won’t have to worry about what happens overnight, you will have a new backup every morning, and you will have a fully charged phone when you wake up.

If you want to know what is draining your battery go to Settings/Battery and it will list the heaviest users of energy over the past 24 hours or the past week.

I strongly recommend going to Apple for the battery replacement. It is the only way to get a battery certified as made for iPhone. And it’s only $49. Many 3rd party batteries do not have the internal battery monitor that drives the state of charge gauge and battery health data.

Google is a very heavy energy user if you use Google Photos or Google Drive. And cellular voice and data are also very heavy energy users, especially if the signal is weak. A 1 bar cellular signal uses 10 times more energy than a 5 bar signal.

But it does sound like there is something abnormal going on with your energy consumption.

Just charge the device when you are not using it.

Really straightforward solution

And it always works, too.