Disgusting Charger I Ever Brought

This is one of the most disgusting charger I have ever seen. I got this rechargable charger with four batteries in sealed from my friend. I really had a good impression at first because the charging time was good. It took 3-4 hours. But after the first charge a foul smell came around the charger and even the batteries also had the same smell. I was using this for my wireless mouse for my computer and it was working fine. But the run time was really bad. Generally if I purchase non rechargable batteries they come upto one week but this one lost its power within 2 days. But I was not thinking much about this because if two of them are charging, I used the remaining two for my mouse. So, I was doing this alternate work for some days but within 20 days if you can see the pic at the bottom of the charger you can see a brown kind of bluged thing poped up which concludes the transformer is gone. So right now I am having those 4 batteries working without a charger. But the lucky thing is I am having an old charger which is working for this rechargable cells but its taking much time to charge.