Dell Inspiron 7720 Laptop - Battery 100%, turns off when not plugged in, have tried new battery

harrrrrrry.

Cable Loose
If you have a cable that is loose, try removing the cable and reconnecting it and make sure it is firmly in place.
If the cable is still loose, check for any bent or broken pins or damage to the connector or cable.

If there is damage to the cable that is causing it to become loose, the adapter and or cable will have to be replaced.

Check the Battery
Right-click the battery icon in the lower right-hand corner, then click Dell Extended Battery Life Options. If this option is not available, proceed to Step 2.
Click the Battery Health tab.
Make note of the message on the page, when the battery shows as "This battery is performing normally", then the battery is performing as it should.

Make sure your bios is updated. You can also run the diags. click the link below.

http://dell.to/2k3NUrH

To run a full diagnostic on your computer, go to the Dell PC Diagnostics page, click the Advanced tab and click Run Diagnostic.
Uninstalling & installing the Battery Driver

If the above steps don’t resolve and you might need to uninstall the battery driver, and then restart your computer. Follow these steps:

Open Device Manager by clicking the Start button Picture of the Start button, clicking Control Panel, clicking System and Security, and then, under System, clicking Device Manager.‌ If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

Double-click Batteries.

Right-click Microsoft ACPI-Compliant Control Method Battery and then click Uninstall.

Restart your computer.

NOTE: After rebooting and installing the driver, update driver software.
Right click "Microsoft ACPI-Compliant Control Method Battery," then select "Update Driver Software."[Notebook needs to be connected to internet] Follow the instructions that appear.