i have a dell inspiron 8600 with the same problem.

dell tech support advises that the power plug (hole) in the back of the laptop is (of course) soldered to the motherboard and that it works loose.
a mere $500 to replace the motherboard (dell says) will resolve the problem. urf.


question about your "fully charged battery from another laptop"
how old is that fully charged battery and what was its usage pattern?
if it is old and was constantly only half used before recharge, the battery may have developed "memory" and cannot be charged but so much.
or the battery could be ancient and simply tired.

an update:

replacing the (external 19v) power supply may very well work.

I have an old and new battery as well as the power supply. No matter which configuration is used the 'in use' battery does not charge. Both batteries and chargers work fine on another machine.

well... by the process of elimination... if you have a known-good power supply that charges batteries in other laptops, and you have known-good batteries that charge in other laptops... sounds like the problems in the "bad" laptop itself... (of course...)

have you tried cleaning the contacts on the "bad" laptop?

if you've already concluded the laptop as "bad" you may wish to disassemble it and look for loose stuff around the power supply input and the battery contacts.
just have a few square feet of clean well lit countertop to work on; i use masking tape rolled inside out into a long loop and stuck to the counter to keep track of all the happy little screws... (they stick to the outside of the loop)

I have had the same problem with an HP some time ago. The problem is a faulty componenet in the charging voltage componenets on the mother board and it is only curable by changing the lmotherboard, so I continue to use the charger / lmains unit and runit from that and also a car 240V converter. sorry not totally portable but a cheap solution!

good luck

I had a similar problem. I decided to dump windows and go to ubuntu. For whatever reason, now it charges fully. The only problem is that sometimes you have to close the lid so it goes to standby and replug it in. Don't know why the operating system would change the charging characteristics.