Macbook charging when off but not when on

A very strange thing is happening, when my Macbook is sleeping or off, my charger charges the battery. However, it charges very slowly (taking around 2days to get to 100%).

When I open/turn on the Macbook it runs off the battery and will shut itself down when it reaches 0%, even with the charger plugged in.

Has anyone had/heard of anyone having this problem before? I have no idea if it's an issue with my charger or my battery (both less than 2 years old) or both. Or more worryingly, something inside which connects the two together.

Any thought would be most appreciated.

The Macbook itself is around 4 years old.

Thanks,

Mike

Do you have another charger you can try with? If the charger's faulty you can see these sorts of issues.

No I haven't yet, but I'm not sure if that is the issue. I forgot to say in my original post, that when I use the Macbook the battery runs down a lot quicker than normal - might this be because the charge is not accurate? (I.e. it thinks it's at 100% when really it's not?).

Thanks,

Mike

Well, you're at the point where you need to eliminate whether it's the battery that's defective or the charger. A new charger is probably easier to deal with. Buy it from a store which accepts returns. A new battery is going to cost more than the charger.

Or, if you have an apple store nearby go see the Genius bar, as them if you can put it on their charger.. or if they'll test your battery