Why does the 150 need a battery box (other than "because it was certified with it")? The 152 has a battery tray, which is easier to maintain and spot problems.
Because the original battery’s cells each had their own vent. A box was needed to capture these corrosive and/or explosive fumes and vent them safely overboard.
The 152’s 24-volt battery was a newer design that vented all the cells internally, with a single vent tube going overboard. In effect, the battery case doubled as the box.
