Mine was sealed from the factory as was the replacement. No acid has to be added nor can it be added to a truly sealed battery. There is no way to add anything because it is sealed tight at the factory. There are many copies out there that are worthless. if you try to cheap it out you may not be getting the real McCoy. I believe I paid about $120 for my replacement and it is great. I never use the Battery Tender but try to run it at least once every two weeks.
OEM lasted five years even in this Southern AZ heat. Normal battery life here is 2=3 years.

Jack