I have an Inspiron with a dead battery, so I bought a new battery. The new battery came with 46% charge so I tried charging it up with the laptop off and charger plugged in overnight. It stayed at 46 so I ran it down to 0 and tried charging again. It will not charge at all; stays at 0. So I returned the battery and got another new one -- same thing happened although the charge was more like 8% out of the box on this one.
Then I noticed that the battery light on the laptop is always off. Whether plugged into AC, battery only, or both. I cannot find any reference to the light being off while plugged in. It looks like it is not trying to charge the battery at all, but how can it run on AC and not be charging the battery? Is there a separate charging circuit?
Probably a blown component on the motherboard or power board. It's the same on a Dell I have -- runs on PSU won't charge the battery.
Luckily I have a couple of other Dells which take the same battery so can charge one in them.
Unless you have done it before I wouldn't recommend trying to fix it. I always take the precaution of buying a wrecked laptop of the same type before trying to open a working laptop. That way I learn where damage can occur when trying to prise the thing apart. Secondly, gives me a source of spares.