Bunny Powers Guest E.P.I.R.B.

IDUNA was equipped with a Guest Model 630 Class B  E.P.I.R.B.  Because the unit's battery pack was out-of-date and Class B  E.P.I.R.B's are scheduled to be phased out, I decided to take the unit apart.  " What to my wonderous eyes should appear," eight class D Energizer brand batteries.  These are wired to give 12 volts.  Mind you, I can well understand why these battery packs cost so much.  There was a styrofoam spacer above the batteries. The whole unit was encased in black heat shrink plastic wrap and labeled with a self-sticking Guest label.
I can see the headlines now, "Bunny Power Saves Liferaft Crew".
Now, I am wondering if the battery packs in the 406 E.P.I.R.P.'s are just aa sophisticated and high tech.