Trough battery spaces between the plates (the troughs) were filled with dilute sulfuric acid. So long as the box was not knocked about, there was no risk of electrolyte spillage. Trough battery The trough battery was a variant of Alessandro Volta's Voltaic Pile and was invented by William Cruickshank c. 1800. Volta's battery consisted of brine-soaked pieces of cloth sandwiched between zinc and copper discs, piled in a stack. This resulted in electrolyte leakage as the weight of the discs squeezed the electrolyte out of the cloth. Cruickshank solved this problem by laying the battery on its side in a rectangular box.
Battery electric multiple unit can travel up to on energy stored in the batteries also recharging the batteries via the overhead-wires when on electrified sections of the line, at stations and via brake regeneration. The trial lasted one month from January to February. Network Rail refer to this prototype model and its possible future descendants as "Independently Powered Electric Multiple Units" (IPEMU). A month after the trial in March 2015, the introduction of battery-powered trains was proposed by Network Rail for consideration for the fifteen station Wrexham to Bidston, Birkenhead, Borderlands Line. The aim is to connect the line onto the electric 3rd rail