yeah showkey and longbox55 are right, and it gets worst most brands will use a variety of designs and price points batteries across their line up and they also change sources from time to time just because a specific battery brand in a certain size group treated you well or poorly doesn't mean much for how well the next will last or how other sizes of the same brand will do.
lately my approach is as follows - find the nearest wrecking yard, they usually have a pile of "tested" batteries for sale usually their price is about $30-35 CAD with NO core charge - that means the dead battery is still worth $20 for core return to the metal recyclers I get a 75% shot at having a great battery for $10-15! sure beats paying $150 for a new one
For 6V i need to buy new, but one time i did saw a 12V in two, there was a dead cell on one side so you can never make 2 x 6V batteries, you have to pick a center cell to sacrifice for the cut the metal recyclers don't care if your battery is sawed in two, they go by weight in that case -s
