The Anonymous Widower

Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?

I ask this question, because I think that it could be key to the announcements about electrification yesterday, as reported  in this article in Global Rail News, which is entitled UK Ditches Electrification Plans In Wales, The Midlands And The North.

If you look at all these Wikipedia entries for Hitachi trains being built for the UK.

You will find no reference to regenerative braking.

If you type “Class 800 regenerative braking” into Google, you will find this document on the Hitachi Rail web site, which is entitled Development of Class 800/801 High-speed Rolling Stock for UK Intercity Express Programme.

The only mention of the R-word is in this paragraph.

An RGS-compliant integrated on-train data recorder (OTDR) and juridical recording unit (JRU), and an EN-compliant energy
meter to record energy consumption and regeneration are fitted to the train.

If you search for brake in the document, you find this paragraph.

In addition to the GU, other components installed under the floor of drive cars include the traction converter, fuel tank, fire protection system, and brake system.

Note that GU stands for generator unit.

Traction System

I will start by having a detailed look at the traction system as described in the document.

The document provides this schematic of the traction system.

Note BC which is described as battery charger.

This is said in the text.

The system can select the appropriate power source from either the main transformer or the GUs. Also, the size and weight of the system were minimized by designing the power supply converter to be able to work with both power sources. To ensure that the Class 800 and 801 are able to adapt to future changes in operating practices, they both have the same traction system and the rolling stock can be operated as either class by simply adding or removing GUs. On the Class 800, which is intended to run on both electrified and non-electrified track, each traction system has its own GU. On the other hand, the Class 801 is designed only for electrified lines and has one or two GUs depending on the length of the trainset (one GU for trainsets of five to nine cars, two GUs for trainsets of 10 to 12 cars). These GUs supply emergency traction power and auxiliary power in the event of a power outage on the catenary, and as an auxiliary power supply on non-electrified lines where the Class 801 is in service and pulled by a locomotive. This allows the Class 801 to operate on lines it would otherwise not be able to use and provides a backup in the event of a catenary power outage or other problem on the ground systems as well as non-electrified routes in loco-hauled mode.

This is all very comprehensive.

But nothing is said about how regenerative brake currents from the traction motors are handled.

Any trained Control Engineer, of which I’m a life-expired example, can see all sorts of questions to ask.

  • Could it be that all regenerative brake currents are fed into the Auxiliary Power Supply and then used for hotel power and to charge the battery?
  • Is the generator unit switched on and off by a sophisticated control system, that uses GPS, train velocity, train weight battery level etc.
  • We know battery power can move the train in emergency, but is battery power used to help start the train?
  • How big is that mysterious battery?

In 2010, I wrote Edinburgh to Inverness in the Cab of an HST, after taking a memorable trip.

One memory of that trip is of the skill of the driver as he adjusted the twin throttles of the power cars and used the brakes, as the train travelled up hill and down dale.

This line will be Class 800 territory and I suspect that it will be worked by two five car units working as a ten-car train.

As I think that each five-car unit will have three generator units, does this mean that the driver will have six throttles?

Control Engineering has moved on in the forty years since the InterCity 125 entered service and I suspect that like an Airline Pilot, the driver of a Class 800 train, will have little control about how power is delivered. Except probably in a supervisory role.

So on routes like the Highland Main Line, the Class 800 will come into its own, using the generator units and stored energy as appropriate.

Obviously, the less the generator unit is used the better, as this minimises noise and vibration, and cuts carbon emissions.

Other features in the train design have been disclosed.

All Class 801 Trains Have At Least One Generator Unit

All Class 801 trains have at least one GU (generator unit), so it can obviously provide hotel power and probably enough power to limp to the next station, in case of overhead line failure.

Third Rail Class 800/801 Trains Are Possible

The layout of the traction system surely makes a third rail  or even a dual-voltage version of the trains possible.

After all, their cousin; the Class 395 train is a dual voltage train.

Locomotive Haulage Is Possible

As I said, the specification is comprehensive.

The document is also forthcoming in other areas.

Train Configuration

This is said.

Trains have a unit configuration of up to 12 cars, including the ability to add or remove standardised intermediate cars and the generator units (GUs)
(generators with diesel engines) needed to operate commercial services on non-electrified lines.

So if say GWR wanted an eleven-car train, it would be possible.

Automatic Coupling And Uncoupling

This is said.

Because the coupling or uncoupling of cars in a trainset occurs during commercial service at an intermediate station, the automatic coupling device is able to perform this operation in less than 2 minutes.

This is definitely in line with Class 395 train performance.

Automatic Train Identification Function

This is said.

To simplify the rearrangement and management of train configurations, functions are provided for identifying the train (Class 800/801), for automatically determining the cars in the trainset and its total length, and for coupling and uncoupling up to 12 cars in
normal and 24 cars in rescue or emergency mode.

I suspect most modern trains can do this.

One Twelve-Car Train Can Rescue Another

See the previous extract.

Flexible Interior Layout

This is said.

The rolling stock is designed to facilitate changes to the interior layout to accommodate changes to services or to the number of cars in the train.

I suspect that was expected.

An Interim Conclusion

In answer to the question, I posed with this post, I suspect that the answer is in the affirmative.

Extra Evidence

I also found this article on the Hitachi Rail web site, which is entitled Hybrid Propulsion with a sub-title of Energy-saving hybrid propulsion system using storage–battery technology.

This is the introductory paragraph.

As a step toward producing environmentally friendly propulsion systems, Hitachi has supplied a hybrid propulsion system that combines an engine generator, motor, and storage batteries. This system provides regenerative braking which has not been previously possible on conventional diesel-powered trains, and enables increased energy savings via regenerated energy.

They list the advantages as.

  1. 10% improvement of fuel consumption
  2. 60% reduction of the hazardous substances in engine exhaust
  3. 30db reduction of noise in stopping at the station

They also give various links that are worth reading.

All of these pages seem to have been published in 2013.


I will be very surprised if Class 800/801/802 trains don’t have batteries.

Will the Class 385 trains for ScotRail have similar traction system?


July 21, 2017 - Posted by | Travel | , , , ,


  1. […] In Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?, I analyse the posed question. […]

    Pingback by UK Ditches Electrification Plans In Wales, The Midlands And The North « The Anonymous Widower | July 21, 2017 | Reply

  2. […] In Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?, I did more than discuss the posed question. […]

    Pingback by Could Hitachi Produce A Bi-Mode Class 285 Train? « The Anonymous Widower | July 22, 2017 | Reply

  3. […] In Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?, I answered the question I posed and I now believe that these trains can store energy. […]

    Pingback by Crossrail 2: City Mayors Criticise Government Backing « The Anonymous Widower | July 25, 2017 | Reply

  4. […] After digging through the various pages on Hitachi’s web site, I wrote Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?. […]

    Pingback by TransPennine Electrification And Piccadilly Upgrade Now Also In Doubt « The Anonymous Widower | July 26, 2017 | Reply

  5. […] In Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?, I describe the electrical systems of Hitachi’s new trains and come to this conclusion. […]

    Pingback by What Is Happening At Waterloo In August? « The Anonymous Widower | August 5, 2017 | Reply

  6. […] In Do Class 800/801/802 Trains Use Batteries For Regenerative Braking?, I quoted this comment from a public on-line Hitachi document. […]

    Pingback by The Automatic Splitting And Joining Of Trains « The Anonymous Widower | August 6, 2017 | Reply

  7. A train has one main power.m controller. In an HST the other controller is for the brakes. Modern units combine this into one lever. It controls all the power units in that train.

    Comment by David | August 11, 2017 | Reply

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