#2. Disconnect Positive Battery Cable. 10 mm combo wrench. 318ti Only?
#3. Remove Battery. 10mm Combo or 10 mm Socket on battery hold-down bolt. 318ti Only?
#4. Unbolt Battey Box. Two 13mm bolts underneath battery. 318ti Only?
Battery + Battery Box Removed. You can see the two battery box bolts rethreaded so I won’t lose them. I think the 318i/is/ic has the battery in the back, so I guess you can omit steps #2, #3, and #4.