The Anonymous Widower

The Stadler Data Sheet For A Class 777 IPEMU

This data sheet is now available on the Stadler web site.

These are my observations.

Battery Charging

The datasheet says this about battery charging.

While an IPEMU is running on the electrified network, the batteries can be charged from the third rail, as well as through regenerative braking.

I’m glad to see the trains have regenerative braking, which in a train with frequent stops saves electricity.

Battery Charging Time

The datasheet says this about battery charging time.

IPEMUs can be recharged in less than 15 minutes.

That time compares favourably with Hitachi’s time.

Expected Battery Life

The datasheet says this about expected battery life.

The IPEMU battery can undergo more than 10,000 charge/discharge cycles, which is about four times the lifetime of a battery used in EVs.

Stadler also give the battery a minimum expected life of eight years.

Transition Between Electrification And Battery

The datasheet says this about this important transition.

Transition between electrified and non-electrified networks without interruption, reducing travel times.

Stadler certainly do the changeover from electric to diesel smoothly on a Class 755 train.

A Comparison To Tesla

This is a paragraph in the introduction of the data sheet.

The battery/vehicle weight-ratio of a Tesla is about 25 per cent, while the ratio of the IPEMU is only about 6 per cent.

I suspect the rolling resistance, is also a lot less, than the rolling resistance of a Tesla, due to the superior properties of steel wheels on rail, as opposed to rubber tyres on road.

Battery Range

The data sheet gives the following.

  • Installed battery capacity – 320 KWh
  • Maximum speed (IPEMU mode) – 62 mph
  • Range in battery operation – 34 miles
  • Maximum demonstrated range – 84 miles


  1. I would assume the 55 km given for range on the datasheet is a guaranteed range.
  2. The maximum demonstrated range is from New Merseyrail Train Runs 135km On Battery.
  3. All other figures are from the datasheet.

In an article in the October 2017 Edition of Modern Railways, which is entitled Celling England By The Pound, Ian Walmsley says this in relation to trains running on the Uckfield Branch, which is not very challenging.

A modern EMU needs between 3 and 5 kWh per vehicle mile for this sort of service.

I don’t think the terrain of Merseyrail’s services are much different from the Uckfield branch, so what are the figures for the Class 777 trains on battery power?

  • 55 km range – 2.353 kWh per vehicle mile
  • 135 km range – 0.952 kWh per vehicle mile

The train appears to be very miserly with electricity.

But if the attention to detail in the electrical system of the train is of the standard of a Swiss watch, I don’t think they are unreasonable.

Operation With 25 kV Overhead Electrification

The datasheet says nothing about this, but the Wikipedia entry for the Class 777 train says this under Design.

Because current regulatory policy makes it unlikely that future extensions of Merseyrail’s unshielded third rail traction power supply will be approved, Class 777 units will be delivered with provision for the future installation of 25 kV 50 Hz AC overhead line traction equipment.

This is probably needed for charging at locations without third-rail electrification.

January 17, 2023 - Posted by | Transport/Travel | , , , , , , ,


  1. With the German Flirts, Stadler bumped up the guaranteed range once they found how the things performed in real life. Something similar may happen with the 777s.

    Comment by Peter Robins | January 18, 2023 | Reply

  2. On class 777, you cannot have tha battery pack configuration, as shown, with 25kv due to limited underfloor space. The 25 kv transformer goes in the space where the batteries are – so it is batteries or 25kv.

    Comment by chilterntrev | January 18, 2023 | Reply

  3. I don’t know about the layout of the power system on the 777, but most trains like the 319s for example have a DC bus, that runs end to end to supply everything. Stadler’s datasheet, shows batteries under the driver cars, with cooling on top. As an electrical engineer, I would suspect that the 777 has a DC bus running between the two batteries. Bombardier use a lightweight transformer on the Aventra, so perhaps Stadler can get away with a super lightweight one, given the frugal nature of the trains. The transformer could go under car 2 or 3. I’d also like to know, where they put the small depot battery.

    This may explain, why they’e gone for a for-car design. But then they know all about the dynamics of Jacobs bogies, which they run at 125 mph in FLIRTs.

    This design is a world-beater!

    Comment by AnonW | January 18, 2023 | Reply

  4. The transformer is not able to go under cars 2 or 3:
    * Space already taken by other equipment
    * Lack of height
    The only free space, when designed, was at either end.

    Comment by chilterntrev | January 18, 2023 | Reply

    • They could have one battery instead of two.

      Comment by AnonW | January 18, 2023 | Reply

  5. […] comment to my post; The Stadler Data Sheet For A Class 777 IPEMU, suggests that batteries can’t be used with the 25 KVAC variant of the Class 777 due to lack […]

    Pingback by Could Class 777 Trains Create A Metro Centred On Preston? « The Anonymous Widower | January 18, 2023 | Reply

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