The Anonymous Widower

More On Batteries On Class 802 Trains

In the December 2021 Edition of Modern Railways, there’s an article called Battery Trial For TPE ‘802’.

Class 802 trains are now involved in two battery trials.

This article puts some flesh of the bones of the two trials.

It is hoped that replacing one diesel engine (generator unit) with a battery pack will enable the following.

  • Reduction of carbon emissions by at least 20 %.
  • Reduction of fuel consumption.
  • The ability to rely on battery power when entering and leaving stations to reduce noise pollution and emissions.

This paragraph explains a possible way the trains will be operated.

Another option is to use the battery to provide ‘classic’ hybridisation efficiency, allowing most diesel running to be done fuel-efficiently under two engines rather than three. In this case, the battery module would provide top-up power for peak demand and give regenerative braking capability when operating in diesel mode, which the trains currently do not have.

This is one of the aims of the GWR trial and I suspect anybody, who has owned and/or driven a hybrid car will understand Hitachi’s thinking.

The next paragraph is very revealing.

To fully test the 6m-long, 2.2m-wide battery module, the intention is for it to be flexibly programmable in order for different approaches to charging, including from the overhead line power supply, diesel engines and during braking , to be evaluated.

It looks to me that Hyperdrive Innovation will earn their fees for the battery design and manufacture.

This picture shows the underneath of a Class 802 train.


  • The car is 26 metres long
  • The car is 2.75 metres wide.
  • The MTU 12V 1600 diesel engines, fitted to a Class 802 train, each weigh around two tonnes.
  • The engines have a power output of 700 kW

I would think that the 6 x 2.2 m battery would fit under the car easily.

As an engineer, who has evaluated all sorts of weight and balance problems, I would make the battery similar in weight to the diesel engine. This would mean that the existing mountings for the diesel engine  should be able to support the battery pack. It would also probably mean that the handling of a car with a diesel engine and one with a battery pack should be nearer to being identical.

Tesla claim an energy density of 250 Wh/Kg for their batteries, which would mean a battery with the weight of one of the diesel engines could have a capacity of around 500 kWh.

As a Control Engineer, I believe that Hitachi and Hyperdrive Innovation have a tricky problem to get the algorithm right, so that the trains perform equally well under all conditions. But with a good simulation and lots of physical testing, getting the algorithm right is very much a solvable problem.

The article says this about the reliability of the diesel engines or generator units (GU) as Hitachi call them.

Whilst reliability of the generator units (GU) has improved, operators of the bi-mode sets still report frequent issues  which see sets ending their daily diagram with one out of use.

I wonder, if battery packs will improve reliability.

From statements in the article, it looks like Hitachi, MTU and the train operating companies are being cautious.

The article also says this about the design of the battery packs.

The battery pack has been designed so it is a like-for-like replacement for a GU, which can maintain or improve performance, without compromising on seats or capacity.

I have always said it would be plug-and-play and this would appear to confirm it.

How Will The Batteries Be Charged?

I showed this paragraph earlier.

To fully test the 6m-long, 2.2m-wide battery module, the intention is for it to be flexibly programmable in order for different approaches to charging, including from the overhead line power supply, diesel engines and during braking , to be evaluated.

GWR and TPE run their Class 802 trains to several stations without electrification. and they will probably need some method of charging the battery before leaving the station.

This is Hitachi’s infographic for the Hitachi Intercity Tri-Mode Battery Train.


  1. This infographic was published with the Hitachi press release announcing the development of the tri-mode train for GWR.
  2. One diesel engine has been replaced by a battery pack.
  3. Charging the battery can be under wires or 10-15 minutes whilst static.
  4. At some stations like Exeter St. Davids, Penzance, Plymouth or Swansea, heavily-laden services might need the assistance of batteries to get up to operating speed.

The infographic released with the Hitachi press release announcing the trials for TPE.

It is similar, but it says nothing about charging.

So how will these trains be charged in stations like Hull, Middlesbrough. Penzance, Scarborough and Swansea, so they leave on their return journey with a full battery?


  • The formation of a five-car Class 802 train is DPTS-MS-MS-MC-DPTF.
  • Pantographs appear to be on both driver cars.
  • The middle three cars have diesel engines.
  • Only the middle three cars have traction motors.
  • There is probably a high-capacity electrical bus running the length of the train, to enable electricity to power all the cars from either or both paragraphs, when running on an electrified line.

The simplest way to charge the batteries would probably be to install a short lengthy of 25 KVAC overhead electrification in the station and then to charge the batteries the driver would just raise the pantograph and energise the electrical bus, which would then feed electricity to the batteries.

I wrote about Furrer + Frey’s Voltap charging system in Battery Train Fast Charging Station Tested. This charging system would surely work with Hitachi’s designs as batteries can be charged from overhead electrification.


I suspect that Hitachi will achieve their objectives of saving fuel and cutting emissions.

But there is more than this project to just replacing one diesel engine with a battery pack  and seeing what the savings are.

It appears that the battery packs could have an effect on train reliability.

If the battery packs are truly like-for-like with the diesel engines, then what will be effect of replacing two and three diesel engines in a five-car Class 802 train with battery packs.

Will it be possible to develop an ability to setup the train according to the route? It’s only similar to the way Mercedes probably set up Lewis Hamilton’s car for each circuit.

But then the speed Formula One cars lap Silverstone is not that different to the maximum speed of a Hitachi Class 802 train.

November 26, 2021 - Posted by | Transport/Travel | , , , , , , , , , ,


  1. Unlike cars, trains travel a limited number of fixed routes and usually fixed schedules, so it should be possible to tune the use of power to the route and schedule

    Comment by MilesT | November 27, 2021 | Reply

  2. I wouldn’t be surprised to see the control system for the batteries using GPS to tune the power automatically. There are at least a couple of buses in London trialling a system like that.

    Comment by AnonW | November 27, 2021 | Reply

  3. I suspect 100% battery operation would be used in the two single Standedge tunnels in NPR. These train would not use diesel. No need for wires in tunnels. The Integrated Rail Plan is to have a high speed line to Marsden. Marsden is the east side of the tunnels. Either they construct two new tunnels, or bore out the existing, or have high speed line to the west of the existing tunnels running on battery through the tunnels, as the train will have to slow up anyhow as the track to the west is slower conventional track.

    The existing tunnels can hold a train but not the overhead wires, however rods can be on the ceiling of the tunnel. But battery seems the best option.

    Comment by John | November 27, 2021 | Reply

    • The battery range of the 802s is given as 5 km. That would get them through the tunnels, especially if the wires on both sides ran close to the portals. I don’t know how wet those tunnels are but there are reports of a lot of corrosion of the overhead lines and brackets in the Severn Tunnel.

      As the Severn Tunnel is only 7 km, you have to wonder if the problems of water in it continue that GWR might run to Wales on battery power.

      Comment by AnonW | November 27, 2021 | Reply

      • Battery train operation though many tunnels, not all, appears the better option. If a line is 100% electrified, batteries are only used through tunnels, so the maintenance costs into account in batteries v constant replacing of overhead wires has to be assessed. Also down time in replacing overhead wires.

        Or they could use 3rd rail/overhead wires trains through the Standedge tunnels because of height, or even the Severn. 3rd rail through the tunnels. The Merseyrail tunnel has a drainage tunnel under, so is subject to moisture – it has 3rd rail.

        Comment by John | November 27, 2021

  4. I’ve always felt that third rail electrification could be used in sensitive areas like tunnels or on top of viaducts. But the powers that be don’t like it.

    Liverpool is even going to have to use battery power to the new Headbolt Lane station, as Healthy and Safety won’t allow third rail.

    Comment by AnonW | November 27, 2021 | Reply

    • Health and safety for Headbolt Lane? I thought it was only for economic reasons.

      Overhead gantries look appalling on viaducts. They are also open to high winds bringing them down.

      Comment by John | November 27, 2021 | Reply

      • Not what I heard, although they may have been playing safe.

        The politicians like overhead electrification, because it’s something you can see and it gives the right message. However, it has problems with trees, is ugly and sometimes causes massive disruption to install. It is also easy to install on a new line, but often a nightmare to install on existing lines.

        So we need to use it only as a last resort or didcontinuously.

        Comment by AnonW | November 27, 2021

  5. Well I knew from a friend of mine who worked on the ventilation contract in the 1990s that it is very wet, but I didn’t remember it was as bad as mentioned in the Modern Railways article.
    The OHL line installed doesn’t surprise me though.

    Comment by fammorris | November 27, 2021 | Reply

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