Motorists with electric cars charge them slowly overnight from domestic supplies at home. Or they can use fast-chargers in places like service stations or supermarkets. GWR used the same principles with its testbed train in West London. For test purposes, the train’s battery rafts were charged slowly overnight in a depot and then with every visit to West Ealing station during the day. From a test perspective, it made sense to start a day with full charge and the fast-charge bursts during the day were essential to test the system. Running a fast-charge battery train in normal service would adopt a different regime. Trains don’t return to depots every night but when they do it makes sense to trickle charge their batteries, just as diesel trains receive fuel in depots. But unlike diesel trains, fast-charge battery trains can be charged as they run, either from overhead wires or fast-chargers in stations. GWR’s test-bed only runs five miles between fast charges because that’s the distance from West Ealing to Greenford and back. In other tests, it has run over 80 miles on a single charge. Modelling suggests it has the potential for much more. Clearly, replacing this sort of power draw takes longer than the 3-4 minutes tested at West Ealing and might typically take just over 15 minutes in a single charge. For the test bed, this fast-charge comes from a set of rails laid in West Ealing station, with one set charging each of the two battery cars of our threecar testbed. Each set is connected to a large battery sitting in a container by the side of the line. Charge reaches these large batteries from conventional electricity network supplies in exactly the same way it reaches homes, shops and offices. The train then takes short bursts via those rails to keep itself topped up. This ability to top up its batteries from lineside supplies gives GWR’s testbed train unlimited range. And, as part of the trial, GWR developed simulation software that can predict power consumption and allows it to suggest where to place lineside fast-chargers along particular routes.