The Anonymous Widower

Brush Traction Signs Contract With Skeleton Technologies For Modules For Class 769 Trains

The title of this post is the same as that of this article on Rail Advent.

This is the first two paragraphs

Skeleton Technologies has announced that they have signed a contract with Brush Traction to supply SkelStart Engine Start Modules for all Porterbrook Bi Mode Class 769 trains.

The high-power density, safe and tiny size of the 24V SkelStart module were decided over other solutions during the feasibility stage to start the Auxiliary Power Supply (APS) units. Simply put, there was not enough room available for another solution.

The article then gives a few brief details on the SkelStart

Who are Skeleton Technologies?

They have a web site at and there is a brief description on the home page.

Under a title of.

Powering Energy Savings With Ultracapacitors

There is this description.

Skeleton Technologies’ patented curved graphene is changing the world of energy storage. 

Our superior technology enables us to deliver ground-breaking energy storage solutions with market leading power and energy density. Our products are used across industries from automotive to aerospace and everything in between.

Curved graphene? I know about graphene, but I’d never heard of it being curved.

There is a Press Release on the Skeleton Technologies web site, which is entitled Skeleton Technologies Signs Contract with Brush Traction to Supply Ultracapacitors for All BMU Class 769 Prime Movers.

This gives a lot more details, including this brief description of size and weight.

The 24V SkelStart has the size of a regular car battery and with its 8kg weight, it solved the space restriction we had.

It looks to be a very simple application of a capacitor with the ability to hold a lot of charge.

One of their products is called a SkelMod 170V 53F Ultracapacitor Module.

The datasheet gives these details.

  • Voltage – 170 Volts
  • Capacitance – 53 Farads
  • Maximum Stored Energy – 0.2127 kWh
  • Weight – 77 Kg.

That is a lot of energy for a capacitor.

A 50 kWh capacitor suitable for a bus or train, with this energy density would weigh eighteen tonnes, so it’s a bit impractical for this type of application at present.

But who knows what will be possible in the near future?

Skeleton Technologies would already appear to have pushed capacitor design a long way.

Skeleton Technologies Are An Estonian Company

This surprised me at first! But why not?

An Aside

Somewhere in my past about the 1960s, I remember an electronic news item, where someone like AERE Harwell, had built a one Farad capacitor, that was house-sized. Noe we get 53 Farad in a suitcase.


I think we’ll eventually see supercapacitors big enough to replace lithium-ion batteries in a lot of applications.

September 20, 2018 - Posted by | Transport/Travel, World | , , ,


  1. that’s interesting. Supercapacitors are appearing in buses and trams, such as some of ADL’s hybrid buses and Alstom’s latest Citadis trams in Nice, but this is the first time I heard of them being used in trains. ‘Curved graphene’ seems to be Skeleton’s trade name. I can see them being used together with batteries, as Skeleton mentions on their website, but I think someone needs to find a way of making the charge longer-lasting before they can replace them. The Nice trams only work because there are no gradients on the coastal route they’re operating on; if they had to go up hills, I think they’d run out of puff part way up.

    Comment by Peter Robins | September 20, 2018 | Reply

    • Stadler are making Citylink trams with batteries for South Wales and not all climbs will be electrified.

      Comment by AnonW | September 20, 2018 | Reply

  2. […] didn’t add any energy storage to the train, although as I said in Brush Traction Signs Contract With Skeleton Technologies For Modules For Class 769 Trains, they have added SkelStart capacitors to start the diesel […]

    Pingback by Ballard Receives Order From Porterbrook for Fuel Cell Module to Power UK HydroFLEX Train « The Anonymous Widower | December 16, 2018 | Reply

  3. I don’t know how Superdielectrics’ polymer-based supercaps compare with Skeleton’s, but there’s a very interesting video on the former’s development plans as given at this year’s MOVE conference at Well worth a watch for anyone interested in advances in this technology.

    Comment by Peter | May 1, 2019 | Reply

    • Thanks for that! I’ll look when I get home! But I do feel supercapacitors could be better in lots of ways.

      Comment by AnonW | May 1, 2019 | Reply

  4. […] supercapacitors on their trains it will not be their first application on heavy rail in the UK. In Brush Traction Signs Contract With Skeleton Technologies For Modules For Class 769 Trains, I describe how supercapacitors are used to start the […]

    Pingback by Skeleton To Supply Ultracapacitors To CAF « The Anonymous Widower | September 3, 2021 | Reply

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