What implications does the latest battery train results have on future UK electrification ?.

[Brubulus]

No put a charging station at Tweedbank it does not need to be a rapid charger just like I charge my car on ‘fast’ charger overnight and that is all it ever needs. Why add a diesel engine when we are trying to decarbonise our railway?

Greenford style chargers will likely become the norm at almost every unelectrified terminus.

 

[waverley47]

No put a charging station at Tweedbank it does not need to be a rapid charger just like I charge my car on ‘fast’ charger overnight and that is all it ever needs. Why add a diesel engine when we are trying to decarbonise our railway?

Or, and you'll hear me out here because this is going to sound bonkers, how about we put up a normal 25kv wiring system at the terminus.

Once it's there, you don't need any special transformers or special fast charging capabilities. You can use the exact same kit as it uses while running under the AC, which saves extra kit. You could even extend the wires a little way, so that they have longer than the five minutes to charge, just in case there's an issue.

All you need is a feeder station (not like one of those was already ordered a decade ago or anything) and some wires. Stringing up the wires a little bit even means you can build the feeder station wherever it's convenient, without needing an extension cable to the station.

You already have a standardised design. No mucking around with consultants or design offices or rolling stock manufacturers, no trails or proof of concepts required. And if in the future, you want to simplify operations and cascade units around the country, it's actually not that much work to wire the bits in the middle, because you have compatible kit at either end.

Funnily enough, I think I might be on to something here...

 

[HSTEd]

Or, and you'll hear me out here because this is going to sound bonkers, how about we put up a normal 25kv wiring system at the terminus.

Once it's there, you don't need any special transformers or special fast charging capabilities. You can use the exact same kit as it uses while running under the AC, which saves extra kit. You could even extend the wires a little way, so that they have longer than the five minutes to charge, just in case there's an issue.

All you need is a feeder station (not like one of those was already ordered a decade ago or anything) and some wires. Stringing up the wires a little bit even means you can build the feeder station wherever it's convenient, without needing an extension cable to the station.

You already have a standardised design. No mucking around with consultants or design offices or rolling stock manufacturers, no trails or proof of concepts required. And if in the future, you want to simplify operations and cascade units around the country, it's actually not that much work to wire the bits in the middle, because you have compatible kit at either end.

Funnily enough, I think I might be on to something here...

Any of that is going to cost many times the fast charger solution.....

The 25kV electrification people had their final bite of the apple over the last decade, and it has not gone very well.

Even if anyone had any faith that the costs could really be got under control with a "rolling programme", it is far too late for that now.
Road passenger transport will be overwhelmingly electric in a decade, freight won't be that far behind. At that point a diesel railway will look like an anachronism.

 

[WAO]

A fast charger has by definition to have a capacity many times that of the traction power of the motor coaches that it feeds. This means that the "charger" has to have much the same rating as a traditional feeder station, even if now a SFC, with peak lopping batteries. The OLE is quite a small part of full electrification costing - 55% is overheads alone! Feeding a small two car unit from underneath is one thing; a full length BEMU will be another. A short length of outward OLE, up to the first low bridge, to provide for acceleration and regenerative braking would also extend battery range, hence discontinuous electrification and battery use are complementary, as has been successful in South Wales.

WAO

 

[PrincesWinsdor]

I am feeling curious how long the life of the batteries are?
how many years can they be used before a replacement is need?

 

[Bald Rick]

A fast charger has by definition to have a capacity many times that of the traction power of the motor coaches that it feeds.

Not necessarily. As an example, an 8 car class 700 has a power output of 3.3MW, and in theory can draw 5MW. However, for a typical St Albans to St Albans via Sutton run, taking 3 hours, it will only draw somewhere in the region of 1.5MWh net, ie if it was powered by batteries, it would only need around 30 mins on the wire at normal charging rates in a 3hr round trip. That’s still a fast charge.

I am feeling curious how long the life of the batteries are?
how many years can they be used before a replacement is need?

Battery life in Road EVs appears to be surprising most motoring journalists (but not those who know about battery technology) and lasting much longer than expected. However the battery technology used in rail applications is likely to be different to most road applications, and designed with a much longer life. I’d expect at least a decade, and more probably 15 years.

 

[Technologist]

I am feeling curious how long the life of the batteries are?
how many years can they be used before a replacement is need?

LFP types can do in the region of 5000-10,000 cycles before they lose 15% of the their capacity.

However that measure is normally for full cycles at relatively slow discharge and charge rates. Charging faster will reduce the cyclic life and partial discharges will increase this life. Typically we are looking at 5-10 years for most utility use cases like trains and battery storage plants.

The key point is that the battery will be very cheap in lifecycle costs, battery EVs have a low per journey cost associated with their battery and a battery train will have far less battery per passenger than a car does.


== Doublepost prevention - post automatically merged: 19 Sep 2025 ==

Not really. An extra 2MWh battery, which you only used once a year, would weigh tons. 10MWh of diesel fuel would weigh only kilograms. And a diesel engine that is hardly used needs very little maintenance. That's why lifeboats on ships have them. And the SUV that will get the MOM out to a bimode BEMU stranded off the wires.

Nope, you will always go for a bigger pack:

1: If you fit a larger pack you do use all of the pack all the time, if you fit a larger pack then your (dis)charges will be at a lower C rate and you will deeply discharge the pack less often. Hence you will get more life out of the pack and your total lifetime spend on batteries will be similar, it might even be lower. A larger pack is pretty cheap and the relatively extra weight you are adding to train is ~1%.
2: You aren't going to get a train stranded off the wires, you are obviously going to have contingency capacity in batteries to mitigate conditions and also the loss of chargers or individual sections of OHLE. But you also have other variable that you can play with, firstly you can take a few minutes longer in certain locations to charge, secondly you can just go a bit slower to increase range though you'd still be going a lot faster than a tri-mode limping on a small diesel.

== Doublepost prevention - post automatically merged: 19 Sep 2025 ==

The primary difficulty for automation of the Underground is the lack of evacuation walkways. I believe that door control should be done in a remote control centre with the assistance of automated technologies. Even if the tracks are no longer directly electrified, it would still be difficult to convince the ORR of the safety of passengers on an unaccompanied train in a tunnel with no walkway, though a direct control centre video link alongside a quick response team could alleviate these fears. Striking will always be an issue for the railway/underground, even automated systems will require safety critical staff at some point, though I can see how batteries could enable automation of the underground.

Battery fire safety is pretty close to a non issue, especially when compared to live exposed electrical currents or hundreds of liters of flammable diesel. EVs will have to put up with what is likely to be more overall abuse compared to the predictable and stable, but intense and constant usage of rail applications, while the physical damage and G loadings faced by automobile batteries are likely to be far higher than rail batteries, even in worst case scenarios.

If we don't have the 3rd and 4th rails, what's stopping people just walking along the tracks? We could either put in moveable fillers (see level crossings) or re-fit with recessed rails/tram track, that would also make a good surface for recovery vehicles to run on. Potentially every station in a tunnel could have a UGV in it which if a train stops could be with it in about a minute (think 1/5th scale RC monster truck, with cameras, lights, microphone/speaker/screen, first aid kit/de-fib attached, available from Ukraine for a very reasonable fee once the machine gun is removed). Recovery crews could be there on electric quads a few minutes later.

 

[WAO]

Not necessarily. As an example, an 8 car class 700 has a power output of 3.3MW, and in theory can draw 5MW. However, for a typical St Albans to St Albans via Sutton run, taking 3 hours, it will only draw somewhere in the region of 1.5MWh net, ie if it was powered by batteries, it would only need around 30 mins on the wire at normal charging rates in a 3hr round trip. That’s still a fast charge.

That's a good example, 56 miles round trip, with about 2/3.3 kWhr per km/mile/car - quite efficient probably with regen (Budget for 3/5kWhr per car). It works for a gap, i.e starts and finishes under the wires. However 1500kWhr requires (at 10kg/kWhr) 15t of batteries, including a frame/control allowance. If the batteries are used 20/80% only then we need 15/.6 = 25t of batteries over 8 cars for the full journey but perhaps half that if charging under the wires 50% of the run. That's still only 28 miles range but certainly useful in some situations. I doubt if it would displace the third rail supply at £100/kWhr battery cost for each unit.

I was thinking of Doncaster/Micklefield - Hull etc for terminal charging, necessary with present likely battery range. Windermere shouldn't need any shore supply for a round trip.

The back of my envelope is rather full!

EoE of course.

WAO

 

[Technologist]

That's a good example, 56 miles round trip, with about 2/3.3 kWhr per km/mile/car - quite efficient probably with regen (Budget for 3/5kWhr per car). It works for a gap, i.e starts and finishes under the wires. However 1500kWhr requires (at 10kg/kWhr) 15t of batteries, including a frame/control allowance. If the batteries are used 20/80% only then we need 15/.6 = 25t of batteries over 8 cars for the full journey but perhaps half that if charging under the wires 50% of the run. That's still only 28 miles range but certainly useful in some situations. I doubt if it would displace the third rail supply at £100/kWhr battery cost for each unit.

I was thinking of Doncaster/Micklefield - Hull etc for terminal charging, necessary with present likely battery range. Windermere shouldn't need any shore supply for a round trip.

The back of my envelope is rather full!

EoE of course.

WAO

You are being a little pessimistic on battery capacity, a good CATL LFP pack is 160wh/kg would be sensible to use 85-90% of that for end of life conditions.

If we are designing a purpose built BEMU then we can also normally take 10-15% of the pack mass from the nominal structure of the vehicle and use the battery pack to provide that stiffness.

I’ve typically used the IET specs as a very conservative estimate of energy consumption. 4600kwh London to Newcastle for 130m train. Obviously if we designing a BEMU we could do a lot better.

https://assets.publishing.service.gov.uk/media/5a79b82e40f0b63d72fc7f58/tts-redacted.pdf

 

[AndrewE]

You are being a little pessimistic on battery capacity, a good CATL LFP pack is 160wh/kg would be sensible to use 85-90% of that for end of life conditions.

If we are designing a purpose built BEMU then we can also normally take 10-15% of the pack mass from the nominal structure of the vehicle and use the battery pack to provide that stiffness.

I’ve typically used the IET specs as a very conservative estimate of energy consumption. 4600kwh London to Newcastle for 130m train. Obviously if we designing a BEMU we could do a lot better.

https://assets.publishing.service.gov.uk/media/5a79b82e40f0b63d72fc7f58/tts-redacted.pdf

searching that spec for "Battery" gives no hits at all...

 

[Nottingham59]

searching that spec for "Battery" gives no hits at all...

A search for "Energy" produced this:

3.9 Efficiency & Environment TS200 The IEP Units must deliver, as a minimum, the following energy efficiency characteristics when operating from a 25kV Overhead Electric Supply: • A 130m Electric IEP Unit on a journey from Kings Cross to Newcastle under the conditions defined in Annex B shall consume no more than 4600kWh;

 

[WAO]

I make that about 3.4 kWhr/mile (5 car) but non stop or stopping?

The battery weight quoted of 6.25 kg/kWhr does not include ancillaries. Attaching a heavy weight to a monocoque alloy body subject to fatigue may pose a problem.

I hope that it doesn't and we can have perfect equivalence from battery power.

WAO

 

[martin butler]

At some point DMU'S will need replacing, and GBR will be looking at cost, If a new fleet is needed, then it makes sense to introduce Battery/ Electric units, on lines where there is already sections of energised track, such as the GW,Branches, Southern's non electrified branches, Reading to Gatwick, this will free up some classes of modern DMU's that can then replace older units, that will soon be life expired, then as battery use, and charging improves, then new systems, to fast charge, batteries, could then see further introduction of battery units.

 

[WAO]

At some point DMU'S will need replacing, and GBR will be looking at cost, If a new fleet is needed, then it makes sense to introduce Battery/ Electric units, on lines where there is already sections of energised track, such as the GW,Branches, Southern's non electrified branches, Reading to Gatwick, this will free up some classes of modern DMU's that can then replace older units, that will soon be life expired, then as battery use, and charging improves, then new systems, to fast charge, batteries, could then see further introduction of battery units.

Agreed.

My only reservation is that battery units must meet the full service specification. The North Downs Line is heavily used and an International Gateway Tier 1 service in the sense of the 2009 RUS and probably needs 8 cars like the Waterloo - Ascot - Reading service. There would be much sense in common rolling stock.

A battery driven Tadpole is NOT acceptable for the Elizabeth Line terminus, in Silicon Valley, with Gatwick's £2.2Bn new runway, announced today.

WAO

 

[Technologist]

I make that about 3.4 kWhr/mile (5 car) but non stop or stopping?

The battery weight quoted of 6.25 kg/kWhr does not include ancillaries. Attaching a heavy weight to a monocoque alloy body subject to fatigue may pose a problem.

I hope that it doesn't and we can have perfect equivalence from battery power.

WAO

See previous point about using the battery as a structural member, for ever 10 tonnes of battery you add typically you get to removed ~1 tonne of existing structure. In the case of cars the battery pack is now being used as the floor pan of the car, you could likely do something similar in a purpose built BEMU.

This use of the battery as the floor pan also allows you to bolt the interior to the battery and then insert the whole unit into the vehicle. Again the same trick would likely work or a carriage.

Also if we start using automotive technology for the drive train we can likely reduced the mass of those components and also increase their power, automotive have basically gone through multiple generations of traction motor architecture in the last 20 years and build more traction motors in a few weeks than rail has done in its entire history.

 

[WAO]

See previous point about using the battery as a structural member, for ever 10 tonnes of battery you add typically you get to removed ~1 tonne of existing structure. In the case of cars the battery pack is now being used as the floor pan of the car, you could likely do something similar in a purpose built BEMU.

This use of the battery as the floor pan also allows you to bolt the interior to the battery and then insert the whole unit into the vehicle. Again the same trick would likely work or a carriage.

Also if we start using automotive technology for the drive train we can likely reduced the mass of those components and also increase their power, automotive have basically gone through multiple generations of traction motor architecture in the last 20 years and build more traction motors in a few weeks than rail has done in its entire history.

I'm not sure that a battery could double up as a rail vehicle structural member, though I am open to learn. What supports the body when they're removed?
My oldie, C19 approach would be to contain the batteries in a stout, crash-proof frame, unfortunately adding weight. I would also want this to be attached to the suspension mountings and draw bars, in effect an under-frame, as I would not trust a moocoque Aluminium alloy body not to suffer early fatigue cracking with vibrations in traffic, whatever the natural frequency.

I never did have anything fall to bits during my career so perhaps I always over designed.

WAO

 

[BrianW]

I'm not sure that a battery could double up as a rail vehicle structural member, though I am open to learn. What supports the body when they're removed?
My oldie, C19 approach would be to contain the batteries in a stout, crash-proof frame, unfortunately adding weight. I would also want this to be attached to the suspension mountings and draw bars, in effect an under-frame, as I would not trust a moocoque Aluminium alloy body not to suffer early fatigue cracking with vibrations in traffic, whatever the natural frequency.

I never did have anything fall to bits during my career so perhaps I always over designed.

WAO

Unlike WAO I am no engineer. I am reminded here of the Pacer, unloved by many BUT arguably a 'success' in terms of longevity. Many industries have difficulties learning from others. AIUI the Pacer was very much a derivative of a Leyland Bus. Surely increasing use of batteries and elimination of diesel offers great scope for standardisation and phased replacements of every DMU, esp if temptations to 'overdesign' (aka 'goldplating?) can be resisted?

 

[Brubulus]

Unlike WAO I am no engineer. I am reminded here of the Pacer, unloved by many BUT arguably a 'success' in terms of longevity. Many industries have difficulties learning from others. AIUI the Pacer was very much a derivative of a Leyland Bus. Surely increasing use of batteries and elimination of diesel offers great scope for standardisation and phased replacements of every DMU, esp if temptations to 'overdesign' (aka 'goldplating?) can be resisted?

There's definitely an argument for a modern Pacer. 5 Enviro200EVs stuck together would almost certainly be cheaper than a modern low floor train. Would have similar capacity to a 3 car train and a range likely in excess of 150 miles.

 

[dubscottie]

Dart+ on the East coast of Ireland put back to 2027. Batteries are, well not good.

I did hear there were issues but now its confirmed. Messroom talk mentioned they were only putting out 40% power even when fully charged.
This is an issue apparently with the battery supplier not Alstolm as per Irish government committee hearing.