hi,
During the 1940s/1950's there was a small company in Yorkshire UK that converted old 12V Lead Acid batteries into about 96V.
By adding plate separators between each individual plate of the typical 8 plates used for a 2V Cell.
So 2v * 8plates * 6cells= ~96V, obviously the Ahr rating was reduced, but the radio high tension side required a low current.
Many house radio's were powered by a 2V Lead Acid Accumulator battery, for the radio Tube/valve heaters and a nominal 90V 'dry' battery, for the 'High Tension'.
In those days some local shops offered a 2V Accumulator hire and recharge service.
The 90V dry batteries were expensive, so the above company doing the 12V Lead Acid conversion to 96V, offered a weekly home delivery and battery exchange service.