Here it is in all its glory! They are not a very large item in this 4 volt standard form. ( the early "block" accumulators and the later 1929 6 volt were much bigger). These were brought in by Meccano from the SECO battery company. They were in 6a and #7 outfits, as well as the X2 electrical sets from the early 20's up to around the end of 1928/beginning of 1929. When the motors were upgraded to 6 volts, the accumulators would not fit easily in the chests anymore and the fact that they were a messy item, the Ferranti transformer of the day was its replacement. By March 1929, they were packing 6 volt motors into sets so the accumulator suitable was left out and replaced with a transformer.