Strange power adapter problem

I've got a problem with my 4 year old LG LW75.

About a year ago, the power to my laptop would die, and it would only run until the battery drained. After a few hours the adapter started working again and would work for many hours until it died again.
This happened for a few weeks.

I bought a voltmeter to check the adapter, but I never got a chance to test it because now it worked perfectly.

A few weeks after that, the battery stopped working completly, and then it would ONLY work with the power adapter, without problems???
So I pulled the battery from the laptop and have been using it for a few months now without it shutting down.

A few days ago, I decided to test the battery again, but it wouldn't work.. but now the problems started with the adapter again. It's been continuing, even though I've pulled the battery again. (don't even know if's a related problem).

I've done som tests and this is what I have.
The computer will work for maybe 12-24hrs without problems, then all of a sudden it shuts down.

I tested the adapter with a voltmeter when it stopped working, and it outputs nothing.

1. if I just leave the cord in the laptop and wall, it won't have power at all even after 8hrs time to cool down.
2. if I pull the cord from laptop for 1 minute and put it in again nothing happens
3. if I pull the cord from the WALL for a minute, and put it in again the adapter will work again for another 12-24hrs.
4. if it was some kind of overheating problem, why would it work for a few months without problems and now suddenly started to die again?

Questions:
1. what could be wrong with the battery? someimes the laptop won't find it, sometimes it says "charging 16%" and won't charge more than that. One day it says "full not charging" but the battery wouldn't work anyways.

2. Doe's the adapter have some sort of fuse or something that resets if you pull it from the wall? I guess it could be an overheating problem but the adapter is perfectly cool if the laptop has died and been off for a few hrs, but the adapter will only work if I pull it from the wall for a few minutes.

Adapter:
100-240V, 50-60hz, 19V, 90W

Sorry for the long post, but wanted to be specific.

Should I just buy a new power-adapter for $50 and just hope it works without trying to understand what the heck is going on?

 

That is some weird stuff going on..

My guess is the power adapter is faulty. How hot does the power brick get?

Your battery sounds like it has dead cells now, well it is 4 years old.

Yes buy a power adapter for now and if it doesnt work then return it.

 

Thanks for the reply!

I've placed an order for a new brick, I'm very sure it's faulty. I find it kind of funny that the power brick first started to malfunction, and only the battery was good, then the battery broke and only the powerbrick worked, and now the battery is completly dead and the brick functions for 12hrs-24hrs.
Don't think I want to waste $150 to get a new battery, guess I'll buy a new laptop, looking at the dell 14z.

Talked to an electrician and he couldn't understand how the brick could act like it does..