Yes, you do not know the series count of your battery, and are therefore in serious danger of an unstoppable chemical fire that cannot be put out with standard fire extinguishers.
The voltage designation you have given is MEANINGLESS. The series count will give you the hard data you require, in order to determine the correct voltage for your battery. 50.4, 54.6, 58.8. It is almost certainly ONE of these. If it is the first, then GET IT OUT OF THE HOUSE NOW. If it was, and you do not post again, well, it was nice knowing you.