Battery Drains Overnight.... While Powered Off?

[8w2w1e2]

At night, at least (twice?) now, I've powered off my phone around 60%.

The first time, I didn't even realize anything happened. I turned on the phone and it restarted... then turned itself off. It was dead.

This second time, I woke up and powered the phone on. I saw it opened up right where it left off around 65%.... however, within a minute, it dropped to about 30-35%. Then, the battery drained extremely quickly..... 1-2% every 10-20 seconds....... I plugged it in the charger around 14%, but it CONTINUED to drain down to 8%, when it finally started charging again.

Any idea what this could be?

Edit: Thank you very much for your replies.

An update with the situation. When I plug in the phone, it charges normally (fast charging cable). I use it normally. I downloaded AccuBattery to track the battery. Not really sure much weird stuff is being picked up by AccuBattery either. The battery drain only happens after I power the phone on after powering it off to go to sleep. During the day, it's basically a normal phone. It's extremely confusing. I did catch last morning the battery apparently using 1,890mA (-481.7%/hr) while plugged in and supposedly charging (which was not the case, as I was watching the battery drain although it was plugged in).

[Pugs1957]

Sounds like the battery can no longer hold charge so needs replacing.

[Babishko]

I have a Note 9 as my second phone @8w2w1e2 and it has the same problem as your S9. It takes a reasonable amount of time and use to get from 100% to 40% but then the battery starts to burn away faster and faster until it reaches 20%. Then it nosedives.. losing 2% every 10 seconds until it dies. When it is dead ONLY wireless charging will get it recharging. If I use my conventional plug in charger nothing happens. This only happens when the battery is empty though.
As Pugs1957 suggests it sounds like our batteries are on the way out pure and simple. I love my Note 9 and it makes a brilliant second phone so I may invest in a new battery for it one day but I will see how long it remains useful for if I keep it charged above 50% as often as I can. Good luck with your S9 @8w2w1e2. 👍👍

[8w2w1e2]

Thanks for your reply.

That's highly unfortunate, the phone is brand new 😕

[8w2w1e2]

That's super unfortunate