XPS 13 9380 Battery dropped down from 45% to 5% suddenly

This model was released in March, 2019 so it's older than you think.  And at 5+ years old, the battery is beyond its design lifespan by close to a factor of two.

You need a new battery -- what you didn't need is a new AC adapter (unless the issue was that the system wouldn't charge from the original).

https://www.parts-people.com/index.php?action=item&id=28889

You may have purchased second hand laptop as the XPS 9380 was released in early 2019.  If the battery is original, it's due for replacement.  The incorrect capacity and drainage report could be symptom of a failing battery.

To restore and improve battery life, watch this YouTube video to learn how to increase the battery life on a Dell laptop https://youtu.be/RXHCGBhBP7M 

Learn how to check the battery health status in BIOS, SupportAssist or ePSA Preboot System Assessment diagnostics, or Dell utilities such as Dell Power Manager or Dell Command | Power Manager.

https://www.dell.com/support/kbdoc/en-us/000124397/how-to-check-battery-health-status-on-dell-laptops

 If nothing helps, consider to replace with an OEM battery https://www.parts-people.com/index.php?action=item&id=28889

@ejn63​ I went to the market and the laptop shopkeeper said the charger has blown so i bought a new  charger ( ac adapter ) because my old ( original one ) stopped charging. It is 65 watt so if i charge works great but the problem is that when i unplug it my pc battery starts draining fastly 1% in 1 minute. I think my old charger has also damaged my pc battery. So now do i need a battery replacement? My pc was working great until my charger blown. I bought the new one after a week. Now the battery only lasts 1 hour if unplugged although xps 13 9380 has originally short battery lifespan like 3 to 4 hours.  I just want to know that nothing would happen if i charge my pc with 65 watt instead of 45 watt charger? And ofc the battery is due for replacement.

The system ships with a 45W adapter so though a 65W will work -- and possibly charge the battery faster -- it has nothing to do with the battery runtime.

You can verify the remaining charge capacity of the battery with a battery report (open a command prompt with admin privileges and type 

powercfg /batteryreport

It will report the current and design charge capacity of the battery.  

@ejn63​ i want to ask can i use my original battery ( which is due replacement ) for some months because currently i cant buy new one? Will this battery damage my pc? Or is it ok ?  

@ejn63​ my battery seems fine but drains battery 1% in 1 minute. But still worth it. Can i use it? This laptop XPS 13 9380 battery originally lasts 3 hours. So according to my pc situation it last only 1 to 1 and a half hour. 

@ejn63​ is battery drainage 1% in 1 minute normal? On Pc which battery lasts only 3 hours normally?