Why didn’t it back up last nite it was plugged in
Hey there, Prendon1!
From your post, it sounds like you are having issues with your iPhone performing an iCloud backup when it’s plugged into the charger overnight. We’re glad that you reached out to the Apple Support Communities. We want to try and help you find the answers you need.
To start, check out this guide for what to do If you can't back up to iCloud. As it shows there, you'll want to make sure you have enough available iCloud space. Make sure you're connected to a strong and reliable Wi-Fi signal.
Also, is your iPhone on the current iOS software? If not, make a backup of the device and update the software. Here's information on how to backup and update:
If the software is up-to-date, you may want to Restart your iPhone if you haven't already. This simple step will often refresh the apps and software on the device to solve numerous problems you may encounter.