Inspiron 5559 Battery draining.

Hi, 

I have a dell Inspiron 5559 Core i7 6500U 2.5GHz laptop. I lost my dell original charger then I bought a charger from a local store. I'm from Sri Lanka and unfortunately there is no Dell Store here. So many local retailers are saying that "WE ARE THE OFFICIAL DELL PARTNERS" but I believe none of them are authorised dealers. The reason I said that is that's why I bought the charger from a local store.

That salesman ensure this is the correct charger for my system but after few weeks I realise my battery life is decreasing faster than before. Very recently I have replaced my Ram with Kingston HyperX 16GB kit. (8GB Ram came with the system) I noticed that battery draining was after this Ram replacement. I'm not sure which one is the reason for battery draining. But Dell Power Management application shows " Battery Status: fair" .. 

My Question is what should I do? As I said there is no original part distributor in Sri Lanka as far as I know. I have checked the Dell official website but it says they have been discontinued supplying the relevant battery module which is suits for my laptop.

1. Is there any way I can purchase a one in online?

2. Even if I bought a new battery would that charger will effect in a negative way for the new battery as well? 

Help me I'm lost