[Arran]

These used an "AB" battery pack that was held in by the back door, hence that strange multi prong plug, the Batterymaker could tell you which types would have worked. It's kind of a strange concept since the "A" section likely would have run down first while the "B" section was still good, unless they compensated for that by making the "A" section larger then a dedicated portable size "A" battery. The later tube portables dispensed with "A" batteries and used "D" cells in parallel. You could still operate one of these from batteries but you would have to engineer a holder to use modern types like 9 volts and "C" or "D" cells in whatever combo is required to supply the voltages and currents needed.
Regards
Arran