Welcome.
Areyou saying you shut off all of the breakers before cinnecting the battery and you get an spark when connecting the negative terminal?
Or are your breakers tripping when connect the terminal.
I think you are saying the former. If so, a spark when connecting the negative terminal should not kill the battery.
Are you keeping the battery charged? What kind of rig? How are you using the batteries (boo docking a lot, running batteries down below 50%,etc.)?
How many batteries do you have?