Laptop Battery doesn't charge fully?

[owennguyen]

Hi guys, I have a laptop, Dell Latitude E5420. Recently, my laptop battery doesn't charge past 33%. When it charge to 33%, it notify "plugged, not charged". What is problem ? It comes from laptop hardware, adapter or battery ? Thanks.

[torbjorn]

Does the battery have a LED bar and test button? If so, what charge level does it show?

Is it any difference whether you look at the charge status with the operating system (probably Windows) running or if you look at it in the BIOS setup?

Check if there are any BIOS or driver updates available for that computer, that adresses battery charging issues. Usually, you will have to search and download the update file and then look in an attached text file to see exactly which issues are fixed.

If you run the computer on battery, do you get the expected run time for 33 % charge?

Is it any difference whether you have the laptop switched on or not while charging?

Does the laptop run well on your mains adapter without battery?

I think you should suspect the battery if any of the following is true:
-Battery is more than two years old.
-Aftermarket battery from unknown or suspect manufacturer.
-Battery looks swollen.
-You know that the battery has been misused at any time (for instance, have been left discharged for a long time, subjected to strong heat, tried to charge or use the battery at extreme cold).

If you have access to another similar laptop, try to swap the batteries between them and see if the problem follows the battery or the laptop.

[owennguyen]

Thank torbjorn.
Based on your idea, I borrowed my friend's laptop and swap the batteries between them. The problem did not happen. I bought new battery , and it works well now.

PS: I unpacked my old battery and tested it. My lapttop battery has 9 cells. After checking, I explored that there are 2 cells was dead