What year is the boat? Does it have a euro transom? My 2002 205 has the euro transom and only came with one battery, located where you describe. It is a little tight, but I added a second battery in that location. The one closest to the transom sits parallel to the transom, while the one closest to the access door sits parallel to the keel. They are a bit of a pain to get in & out, and you need to take out the forward one to remove the back one. But it works.