battery performance for iPhone se recently has been very poor

Hello ~ What model SE? Take a look here by clicking on below…

Identify your iPhone model - Apple Support

Check your battery health percentage…

Check the iPhone battery health and usage – Apple Support

What is the percentage? Post back with details and if your % is 80% or below you need a new battery. Take care.

~Katana-San~

The general answer is that you have an app that is using more energy than usual. But based on the amount of information you have provided, a more detailed answer is impossible. Some basic questions:

• What model phone (you said SE, but is that a first, second or third generation)?
• What version of iOS?
• How much storage does the phone have?
• How much storage is free?
• How long has it been since the phone was new?
• Has the battery ever been replaced? If so, when was the battery replaced?
• What are your charging habits - when do you charge, to what % do you charge, and what is the % when you start charging?
• If you go to Settings/Battery, which apps are using the most energy, and how much?
• If you go to Settings/Battery/Battery Health, what does it say under Peak Performance, and what is the Maximum Capacity?

If you can provide this information it will go a long way towards a discussion of your issue.

Unlikely, as it hasn’t happened to hundreds of millions of other phones. Have you updated to 15.5.1(c)?

But you should be charging overnight, every night.

Have you tried a forced restart?