GWR says that this technology, which is capable of charging trains at up to 2,000kW (8 times more powerful than a Tesla Supercharger for example), has been in development for three years and will solve the problem of delivering a reliable service with battery-only trains.
At West Ealing, the trains, which are former London Underground units, will undertake real-world trials and will charge for just 3 and a half minutes before restarting its journey on the Greenford Branch Line.
Using battery trains negates the need for overhead electric wires, which GWR says are expensive and impact the landscape.
GWR says it wants to pave the way for more battery-only trains to come into operation across the UK.
Unlike other charging systems, GWR's FastCharge technology, which was purchased by GWR from VivaRail when the company went into administration, can be installed between the running rails in a matter of hours, with little to no disruption to passengers.
FastCharge uses short charge rails that are fully covered by the train and only become ‘active' when the train is charging, which is another benefit over and above Third Rail systems, which are used in London and the south, as well as on the MerseyRail network, where the power rail is live all of the time.
GWR says it has already carried out simulations on the branch lines in the Thames Valley to explore how a wider roll out could happen in the future.
Test runs have been carried out on the test lines at Long Marston Rail Innovation Centre (RIC), but the Class 230 battery trains have now begun testing on the mainline between Long Marston, Evesham, Honeybourne and Moreton-in-Marsh before heading to GWR's Reading TrainCare Depot, before moving onto West Ealing.
GWR Engineering Director Dr Simon Green said: “This work has never been done before and we're leading the way to help the Department for Transport and Network Rail understand what is required to roll out this technology on the UK's rail network.
“Only now has there been a combination of battery capability and charging technology that enables a branch line train to operate to the same timetable as a diesel unit, and yet still charge safely and with minimal impact on the local grid power supply.
“Clearly our specialist engineering team have been working round-the-clock to ensure that this FastCharge system has been fully tested and that there will be sufficient charge for the train to operate to the timetable on the Greenford branch line.
“Each branch line will vary but this is an incredibly exciting innovation and I'm proud that GWR is at the forefront of the railway's commitment to phase out diesel-only traction by 2040.”
Network Rail Interim Regional Managing Director, Rob Cairns, said: “This trial marks an important milestone in sustainable travel in the UK. Rail is already the greenest form of public transport and battery-powered trains have the potential to play an important role in our commitment to a low-emission railway, with a goal of reaching net-zero by 2050.”