Question Weird laptop battery behavior, went from 90 to 0 to 50

[Bitzsec]

Hello everyone,

My issue is a bit weird and spooky behaviour of my laptop's battery (Dell latitude 5500 running on Windows 10).
First of all, the battery life so good that it lasts for roughly 8-10 hours of work and has battery health of 71.5% and shows "Excellent" in the bios.

But, two events happened that are so weird:
First event:
1. Battery is 100% and slowly discharged over 8 hours until it reached 16-18% and the laptop shutdown unexpectedely
2. When I tried to power it on again it will just light the power buttom led up then turns off after 2 seconds
3. I plugged my AC adapter in and it started to charge and I found the battery level is 1%

Second event:
1. Laptop was plugged in and the battery is 100%
2. Suddenly while working the laptop hibernates
3. When I turned it on again, the battery level is 50%

All I get in the event viewer for this is Kernel-power: Critical Battery Trigger Met and The system is entering sleep, Sleep Reason: Battery

So, what's causing those two strange behaviour?

 

[punkncat]

I would call it a sign of a failing battery. Probably best to start looking for a quality replacement.

 

[Bitzsec]

I would call it a sign of a failing battery. Probably best to start looking for a quality replacement.

If it's failing how it's giving a good operating time + how come it goes from 1% to 50%? And when I tried to run it off batteru, it went on for 5 hours from 50% to 9%

 

[ex_bubblehead]

Assuming that that's the original battery then it is most definitely at the end of its life. This is exactly what you can expect to see at this point. There's nothing you can do to revive it. It must be replaced. Don't go generic, always use OEM.