Hello Pat,
Thanks for reaching out to the Apple Support Communities. I understand that your iPhone SE is exhibiting limited battery life even while not in use. I’ll be happy to look into this with you. Here are some troubleshooting steps that I start with when I have noticed a change in the battery life on my iPhone.
1 - The first thing to do will be to see which iOS version number was installed. You can do this by going to Settings > General > About > Version. iOS 13.3 has recently been released. Keeping your iPhone up-to-date ensures that you have the latest security updates and performance enhancements. Before updating your iPhone be sure to create a backup of your iPhone data. Having a backup of your data is like having an insurance policy, you don’t plan on using it, but it’s great to have if you need it. Here’s how to back up your iPhone: How to back up your iPhone, iPad, and iPod touch.
Once the backup is complete, please install the update. You can update your iPhone using either wireless over-the-air updating or update using your computer: Update your iPhone, iPad, or iPod touch.
2 - Take a look at the Battery Health by going to Settings > Battery > Battery Health. Here you can see the Maximum Capacity of your battery and the Peak Performance Capability. This article will give you details about what you can learn from this information: iPhone Battery and Performance. If you’re seeing anything below 80% maximum capacity or normal for peak performance capability. There may be an issue with the health of your iPhone.
3 - The next thing to do is to check and see how your apps are using the battery power. If your iPhone was up-to-date, and it’s been more than 24 hours since you installed the latest iOS 13 update, go to Settings > Battery and look at the list of apps below the list. This shows you how long the app has been on screen, running in the background, and the percentage of battery power it’s used out of 100%. If you see any that are unusually high over the last 24 hours, I’d uninstall the app and use the iPhone for another 24 hours without that app present. See if there’s any change. If there is, you know that the app was causing the excessive drain on the battery. This article will give you more information about the data shown: About the battery usage on your iPhone, iPad, and iPod touch.
If you find you make any changes to your iPhone, removing apps or changing settings, be sure to use it for 48 hours and check again to see if there is any improvement. Message back with the results, and let me know if any of this information is helpful.
All the best!