The Anonymous Widower

Batteries On Class 777 Trains

In this article on Railway Gazette, which is entitled Merseyrail Class 777 arrives in Liverpool, there is this sentence.

There is space under one vehicle to house a battery weighing up to 5 tonnes within the axleload limit.

This matter-of-fact sentence, draws me to the conclusion, that these trains have been designed from the start to allow future battery operation.

Batteries are not an add-on squeezed into a design with great difficulty.

Battery Capacity

Energy densities of 60 Wh/Kg or 135 Wh/litre are claimed by Swiss battery manufacturer; Leclanche.

This means that a five tonne battery would hold 300 kWh.

Note that Vivarail find space for 424 kWh in the two-car Class 230 train, I wrote about in Battery Class 230 Train Demonstration At Bo’ness And Kinneil Railway, so it would appear that Stadler aren’t being over ambitious.

Kinetic Energy Of A Full Class 777 Train

The weight of a full Class 777 train is calculated as follows.

  • Basic empty weight – 99 tonnes
  • Battery weight – 5 tonnes
  • 484 passengers at 80 Kg – 38.72 tonnes

Which gives a total weight of 143.72 tonnes.

Intriguingly, the weight of a current Class 507 train is 104.5 tonnes, which is 500 Kg more than an empty Class 777 train with a battery!

If these weights are correct, I suspect Stadler have used some very clever lightweight design techniques.

For various speeds, using Omni’s Kinetic Energy Calculator, this weight gives.

  • 30 mph – 3.6 kWh
  • 40 mph – 6.4 kWh
  • 50 mph – 10.0 kWh
  • 60 mph – 14.4 kWh
  • 70 mph – 19.5 kWh
  • 75 mph – 22.4 kWh

Note.

  1. The average speed between Bidston and Wrexham General stations on the Borderlands Line is under 30 mph
  2. The operating speed on the Wirral Line is 70 mph
  3. The operating speed on the Northern Line is 60 mph
  4. The maximum speed of the trains is 75 mph.

Every time I do these calculations, I’m surprised at how low the kinetic energy of a train seems to be.

How Small Is A Small Battery?

One battery doesn’t seem enough, for a train designed with all the ingenuity of a product with quality and precision, that is designed to out-perform all other trains.

This is another paragraph from the Railway Gazette article.

According to Merseytravel, ‘we want to be able to prove the concept that we could run beyond the third rail’. By storing recovered braking energy, the batteries would help to reduce power demand and the resulting greenhouse gas emissions. All of the Class 777s will be fitted with small batteries to allow independent movement around workshop and maintenance facilities.

I am not quite sure what this means.

It would seem strange to have two independent battery systems in one train.

I think it is more likely, that the smaller battery can be considered the primary battery of the train.

  • After all in the depot, it looks after the train’s power requirement.
  • Does it also handle all the regenerative braking energy?
  • Is it used as a secondary power supply, if say the power is low from the electrification?
  • Could it be used to move the train to the next station for passenger evacuation in the event of a power failure?

I wonder if the power system is a bit like the average battery-powered device like a lap-top computer, smart phone or hybrid car.

  • The electrification and the regenerative braking charges the battery.
  • The battery provides the traction and hotel power for the train.

When the five tonne battery is fitted, does the train’s control system move power between the two batteries to drive the train in the most efficient manner?

I’ll return to factors that define the size of the small battery.

The small battery must be big enough for these purposes.

  • Handling regenerative braking at the operating speed.
  • Recovering a full train to the next station.
  • Keeping a train’s systems running, during power supply problems.
  • Moving a train around a depot

As the lines leading to depots are electrified, the train can probably enter a depot with a battery fairly well-charged.

As the new Class 777 trains have a maximum operating speed of 75 mph, I would suspect that the small battery must be able to handle the regenerative braking from 75 mph, which my calculations show is 22.4 kWh with a full train. Let’s call it 30 kWh to have a reserve.

Using Leclanche’s figures, a 30 kWh battery would weigh 500 Kg and have a volume of just under a quarter of a cubic metre (0.222 cubic metre to be exact!)

I suspect the operation of the small battery through a station would be something like this.

  • As the train runs from the previous station, the power from the battery will be used by the train, to make sure that there is enough spare capacity in the battery to accommodate the predicted amount of energy generated by regenerative braking.
  • Under braking, the regenerative braking energy will be stored in the battery.
  • Not all of the kinetic energy of the train will be regenerated, as the process is typically around eighty percent efficient.
  • Whilst in the station, the train’s hotel services like air-conditioning, lights and doors, will be run by either the electrification if available or the battery.
  • When the train accelerates away, the train’s computer will use the optimal energy source.

The process will repeat, with the battery constantly being charged under braking and discharged under acceleration.

Lithium-ion batteries don’t like this cycling, so I wouldn’t be surprised to see dome other battery or even supercapacitors.

A Trip Between Liverpool and Wrexham Central in A Class 777 Train With A Battery

The train will arrive at Bidston station with 300 kWh in the battery, that has been charged on the loop line under the city.

I will assume that the train is cruising at 50 mph between the twelve stops along the twenty-seven and a half miles to Wrexham Central station.

At each of the twelve stops, the train will use regenerative braking, but it will lose perhaps twenty percent of the kinetic energy. This will be two kWh per stop or 24 kWh in total.

I usually assume that energy usage for hotel functions on the train are calculated using a figure of around three kWh per vehicle mile.

This gives an energy usage of 330 kWh.

But the Class 777 trains have been designed to be very electrically efficient and the train is equivalent in length to a three-car Class 507 train.

So perhaps a the calculation should assume three vehicles not four.

Various usage figures give.

  • 3 kWh per vehicle-mile – 247.5 kWh
  • 2.5 kWh per vehicle-mile – 206 kWh
  • 2 kWh per vehicle-mile – 165 kWh
  • 1.5 kWh per vehicle-mile – 123.8 kWh
  • 1 kWh per vehicle-mile – 82.5 kWh

Given that station losses between Bidston and Wrexham Central could be around 24 kWh, it looks like the following could be possible.

  1. With a consumption of 3 kWh per vehicle-mile, a Class 777 train could handle the route, but would need a charging station at Wrexham Central.
  2. If energy consumption on the train could be cut to 1.5 kWh per vehicle-mile, then a round trip would be possible.

It should also be noted that trains seem to do a very quick stop at Wrexham Central station of just a couple of minutes.

So if charging were to be introduced, there would need to be a longer stop of perhaps eight to ten minutes.

But the mathematics are telling me the following.

  • The Class 777 train has been designed to weigh the same empty as a current Class 507 train, despite carrying a five tonne battery.
  • If power consumption can be kept low, a Class 777 train with a battery can perform a round trip from Liverpool to Wrexham Central, without charging except on the electrified section of line between Liverpool and Bidston.
  • Extra stops would probably be possible, as each would consume about 2 kWh

I feel that these trains have been designed around Liverpool to Wrexham Central.

Conclusion

Wrexham Central here we come!

Other routes are possible.

  • Hunts Cross and Manchester Oxford Road – 27 miles
  • Ormskirk and Preston – 15 miles
  • Headbolt Lane and Skelmersdale – 6 miles
  • Ellesmere Port and Helsby – 5 miles
  • Kirkby and Wigan Wallgate – 12 miles

Chargers will not be needed at the far terminals.

February 4, 2020 - Posted by | Transport | , , , , , ,

12 Comments »

  1. […] Batteries On Class 777 Trains, I quoted a source that said that Class 777 trains are built to handle a five tonne […]

    Pingback by Sparking A Revolution « The Anonymous Widower | February 16, 2020 | Reply

  2. I doubt Wrexham Central would not have a charger at the station. The service is now one per hour. It is scheduled to be two per hour. Maybe three if the service attracts passengers. them timetabling so their a long dwell at Wrexham for charging. It does not need to charge up to full.

    There is space at Wrexham Central for another track and platform.

    Comment by John | July 6, 2020 | Reply

  3. Merseyrail planned to have a terminal at Warrington in 1991. Battery trains can easily do that. I doubt Merseyrail would ever get to Manchester as politics would prevent that. Manchester do not like the idea of Merseyrail reaching Wigan as it is in Gtr Manchester. Although people in Wigan.

    Battery trains could ease the way for the opening of the Outer Loop Line and Wapping Tunnel, as implementation would be cheaper as no track electric infrastructure needed. The Wapping Tunnel is an urgent requirement, giving an east-west crossrail.

    Comment by John | July 6, 2020 | Reply

  4. The one thing we can be sure about these trains, is that they will be quality, if the 745s and 755s of Greater Anglia are anything to go by.

    Comment by AnonW | July 6, 2020 | Reply

  5. I’ve always thought Manchester would be difficult for Merseyrail, but then the Mayor of Greater Manchester is a Scouser.

    I also wouldn’t be surprised to see Stadler targeting Manchester over sales of tram-trains. Having seen, what Stadler have done in Germany with diesel multiple units running as trams in Zwickau, I wouldn’t be surprised to find out that the 777s can street run to the airport or to the docks through the Wapping Tunnel to the River. Would a tram-train capability allow them to invade the Metrolink, which will need more trams in the future.

    The 777s look very similar to the new trains on the Tyne and Wear Metro, so will they turn up on the Metrolink.

    As it seems likely, that Stadler’s Citylinks will be numerous in Sheffield, it looks like Stadler should do the honest thing and build a base in the North.

    Comment by AnonW | July 6, 2020 | Reply

  6. It was announced a few years back that Vivarail diesel trains would be used on the Borderlands line. Meseyrail have said nothing of using class 777 battery trains on the line. They may do if battery train trials are successful elsewhere. If Merseyrail use class 777 battery-electric trains the line with be incorporated into the Wirral line, or better with a new line designation.

    Comment by John | July 6, 2020 | Reply

    • The beauty of the Wirral Loop is that if you put in digital signalling and ETCS, you could run up to about twenty tph round the loop. I think it can handle 14 tph at present. It’s recently been rebuilt, so won’t need major maintenance for a few years hence.

      It would also fully charge the battery trains, as a train takes fourteen minutes to go from Hamilton Square to Hamilton Square.

      We need more loops under city centres.

      Comment by AnonW | July 6, 2020 | Reply

      • The tracks at the platforms at Bidston are 3rd rail. The loop takes in 13 station stops, 15 including Bidston. That is a lot of time to recharge.

        Comment by John | July 6, 2020

  7. The metro-mayor of Manchester is an Evertonian but from Leigh.

    Comment by John | July 6, 2020 | Reply

  8. Stadler’s UK HQ is at Kirkdale in Liverpool. Owned by Stadler – the old MTD. All brand new with a new office block and space to expand. All major overhauls for the UK will be there, for Merseyrail, Tyne & Wear & Greater Anglia. And any other sale elsewhere.

    Tram-trains is still up in the air for many. They have to be built to heavy rail standards, while trams are glorified buses on rail driven at line of sight, built to lesser standards. Tram-trains are expensive so have to be on well used routes.

    Tram-trains were rumoured for the airport from Sth Parkway and along boulevards. However If Liverpool has an airport station the trains may be battery-electric, running from east of Halewood station on new track to the airport past EFCs training ground entering the airport from he east. Trains from Warrington and Manchester could enter via this route, the Liverpool-Mcr southern route. This way offers so much more. Cheaper to do now electrification is not needed.

    Battery trains will make a hell of a difference. Hungary, Austria, Germany and Denmark are all using or are to use battery trains. Even the Japanese bullet train has battery backup. Even Ireland’s new trains will be battery capable.

    Comment by John | July 6, 2020 | Reply

  9. I suspect they’d extend the third-rail at Bidston a bit and put in third rail at Wrexham. They could use Riding Sunbeams, if there’s enough space for the solar panels. That’s something they can’t do in Manchester.

    Comment by AnonW | July 6, 2020 | Reply

  10. […] Batteries On Class 777 Trains, I estimated that, the battery capacity of a Class 777 train was 300 […]

    Pingback by Beeching Reversal – Reopen Midge Hall Station « The Anonymous Widower | August 7, 2020 | Reply


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