The corrosive liquid in the accumulators was sulphuric acid and the metal plates lead, so they were called lead-acid cells. The valves in those old radios operated on 2 volts to heat their filaments, which was the output of the single cell wireless accumulators in those days. As well as the accumulator one also had a non-rechargable dry battery (like a bank of torch batteries in one cardboard package). So far as I can recall they were made in 60volt and 100volt sizes. Concern used to arise when the wireless reception noticeably faded and one had to think about the expense of a new high tension battery. (The accumulator was known as low tension and the dry battery as high tension.)
Couldn't resist joining in with comments. It took me back nearly 80 years to the time when, as a boy, I started to construct wireless sets as a hobby. Started with crystal sets (anybody remember them?) and progressed to valve sets with accumulators and batteries. Very absorbing and put me in good stead when I served for five years in the WW2 RAF.
To relate this to Newham I should mention that I spent my boyhood pocket money on wireless components at a fine shop named Unlimitex in Stratford High Street. I've already said somewhere on this site that when I entered the door of Unlimitex some assistant would shout, "Here comes bloody Marconi!!"