Not intended as a tease or heavy criticism- Important ReminderÂÂÂ
Please if you are reading this: You know not to disconnect the battery, when you have some equipment, alarm systems, and retro fit upgrades on board - well 90% do here.
Normal stuff:
1) Charge up your old battery first - kept from the last change.
2) A piece of decent yet flexible cable four medium crockadile clips, then make your two lighter jump leads, just to maintain the 12 volt supply
3) Connect the crocks up with the correct polarity to the old spare, then
4) Disconnect the good battery for charging.
If you're careful and have nice flexible jump leads, you may then put the old battery back in the battery box, leaving off the lid for the time being.
Much lighter, and flexible leads, than the heavy Starting type are required, with smaller crock clips. Big clips get in the way, and fall off when disconnecting.
That is all.