Could battery stock operate the Buxton line?

[Energy]

Out of interest, how does their power/capacity change over time? Does it slowly decline or does it stay reasonably flat for some years and then suddenly start going down?

What I'm getting at is... assuming you are correct that batteries need replacing after 10 years - is there a risk that after, say, 8 years, the battery would no longer be giving the same acceleration as it did when it was new, or would take longer to recharge, even though it's not yet life expired?

Depends on the battery but they do loose charge over time.

Batteries also have a varying amount of power outputted depending on the charge, lithium ion batteries used in trains, phones etc. provide a fairly consistent amount of power until they start to run low on charge and then they go down much more quickly, here is a graph:


Batteries also change depending on temperature so the range will be different if it is colder or warmer however it doesn't change too much considering the range of temperatures we get in Britain.

 

[DynamicSpirit]

Depends on the battery but they do loose charge over time.

Batteries also have a varying amount of power outputted depending on the charge, lithium ion batteries used in trains, phones etc. provide a fairly consistent amount of power until they start to run low on charge and then they go down much more quickly, here is a graph:
View attachment 80565

Batteries also change depending on temperature so the range will be different if it is colder or warmer however it doesn't change too much considering the range of temperatures we get in Britain.

Thanks, that's interesting, but unfortunately not what I meant: That shows the voltage over one single discharge. My question was more like: After some years of use, does that graph look the same, or will it be lower (or discharge more quickly) - with a corresponding decrease in train performance?

 

[Bald Rick]

Out of interest, how does their power/capacity change over time? Does it slowly decline or does it stay reasonably flat for some years and then suddenly start going down?

What I'm getting at is... assuming you are correct that batteries need replacing after 10 years - is there a risk that after, say, 8 years, the battery would no longer be giving the same acceleration as it did when it was new, or would take longer to recharge, even though it's not yet life expired?

This article about Tesla battery life is useful. Too long to quote.

A look at Tesla battery degradation and replacement after 400,000 miles

In this new installment of our series on the highest-mileage Tesla Model X (and one of the highest mileage EVs...

electrek.co

 

[Energy]

Thanks, that's interesting, but unfortunately not what I meant: That shows the voltage over one single discharge. My question was more like: After some years of use, does that graph look the same, or will it be lower (or discharge more quickly) - with a corresponding decrease in train performance?

My answer to you question was the first line of my message but I should probably elaborate more

Yes batteries do degrade over time, for example notice how battery life on your phone is not quite as good as it was a couple years ago. How much the battery degrades varies depending on the conditions such as heat as the bits inside a battery do get slowly worn away. However the type of battery does affect this and some batteries will last a lot longer, it also depends on how it is charged, you should never let a Li Ion battery go to 0, which battery protection circuity prevents, and doing charges from 20% (bellow this the battery starts to become useless, see the graph I put above) to 100% damages the battery more than charging it when it is half full.

 

[py_megapixel]

My answer to you question was the first line of my message but I should probably elaborate more

Yes batteries do degrade over time, for example notice how battery life on your phone is not quite as good as it was a couple years ago. How much the battery degrades varies depending on the conditions such as heat as the bits inside a battery do get slowly worn away.

I believe this is the foundation of the concern that "fast charging" systems may shorten the life of the battery. They generate much more heat than normal charging.
However, this might well be less of an issue in batteries on the scale used for trains

 

[MarkyT]

Robert Llewellyn's early Nissan Leaf if driven carefully managed 80-95 miles per full charge when new. Ten years later, he's getting 45-55 miles, but he admits to damaging the battery through frequent small top-up charges when already nearly full, which the early battery management system couldn't deal with.

 

[RealTrains07]

Buxton is definitely an ideal place for battery operation for sure

Their is other battery stock that should be given priority over the 331s though.

350/2 BEMUs would be good. Modern, recent and one of the most reliable in the UK. They would be a good suit for battery services in buxton?

 

[DynamicSpirit]

Thanks. That does seem like it ought to be an issue for trains - much more so than for cars. Granted a battery that isn't damaged is probably not going to have it's capaicity drop by the 40-ish% that Robert Llewellyn is claiming. But, given the precise timings that trains need to run to, you'd have thought even, say, a 10% loss in distance per charge, or a 10% increase in charging time, or a 10% loss in power that can be supplied to the train could potentially make scheduled timetables unworkable - unless of course, the timetables are created on the assumption that the battery supplies much less power/etc. than it is capable of. (That compares to - for a private motorist, the battery losing 10% of its capacity over a period of several years is something many drivers may not even particularly notice).

 

[MarkyT]

Thanks. That does seem like it ought to be an issue for trains - much more so than for cars. Granted a battery that isn't damaged is probably not going to have it's capaicity drop by the 40-ish% that Robert Llewellyn is claiming. But, given the precise timings that trains need to run to, you'd have thought even, say, a 10% loss in distance per charge, or a 10% increase in charging time, or a 10% loss in power that can be supplied to the train could potentially make scheduled timetables unworkable - unless of course, the timetables are created on the assumption that the battery supplies much less power/etc. than it is capable of. (That compares to - for a private motorist, the battery losing 10% of its capacity over a period of several years is something many drivers may not even particularly notice).

I'd say the latest battery technology and management systems should ensure much better lifecycle capacity retention than this, and companies providing professional solutions in commercial sectors should be able to give firm guarantees on the matter. Duties must be planned conservatively clearly, and an option on a partially electrified railway as batteries decay is to extend the wired proportion of the route marginally (i.e. add a few miles of simple plain track knitting, not even necessarily continuously if that avoided some bridge reconstruction for example). That could potentially reduce the size, weight and cost of the eventual replacement battery as well, so a win-win!

 

[Bald Rick]

Thanks. That does seem like it ought to be an issue for trains - much more so than for cars. Granted a battery that isn't damaged is probably not going to have it's capaicity drop by the 40-ish% that Robert Llewellyn is claiming. But, given the precise timings that trains need to run to, you'd have thought even, say, a 10% loss in distance per charge, or a 10% increase in charging time, or a 10% loss in power that can be supplied to the train could potentially make scheduled timetables unworkable - unless of course, the timetables are created on the assumption that the battery supplies much less power/etc. than it is capable of. (That compares to - for a private motorist, the battery losing 10% of its capacity over a period of several years is something many drivers may not even particularly notice).

Battery management technology has come a long way in the last decade, and Nissan ar not at the forefront of it. Besides, it would be entirely reasonable to replace battery packs every 10 years or so - it is what is done with Diesel engines, and (notably) some elements of the electrification system (although many elements last much longer). Final thing - whilst battery capacity does deteriorate over time, I’m not aware of any batteries of this scale that have a material deterioration in discharge power over time.

 

[mrgreen]

Batteries seem to be well understood: they need sophisticated control systems to stop degradation but don't need much maintenance.
So why are we even considering using fuel cells which are inefficient, need a supply infrastructure which doesn't yet exist, and I guess will need new skills to maintain?
They only seem to make sense if they use otherwise surplus electricity (e.g. overnight wind generation). But that surplus could be used for overnight charging of battery vehicles anyway.
Am I missing something, or are fuel cells a solution in search of a problem?

 

[Energy]

Batteries seem to be well understood: they need sophisticated control systems to stop degradation but don't need much maintenance.
So why are we even considering using fuel cells which are inefficient, need a supply infrastructure which doesn't yet exist, and I guess will need new skills to maintain?
They only seem to make sense if they use otherwise surplus electricity (e.g. overnight wind generation). But that surplus could be used for overnight charging of battery vehicles anyway.
Am I missing something, or are fuel cells a solution in search of a problem?

Batteries don't have a long range and although fast charging is an option it isn't great for the batteries.

 

[MarkyT]

Batteries seem to be well understood: they need sophisticated control systems to stop degradation but don't need much maintenance.
So why are we even considering using fuel cells which are inefficient, need a supply infrastructure which doesn't yet exist, and I guess will need new skills to maintain?
They only seem to make sense if they use otherwise surplus electricity (e.g. overnight wind generation). But that surplus could be used for overnight charging of battery vehicles anyway.
Am I missing something, or are fuel cells a solution in search of a problem?

I think hydrogen could work where distance on very lightly used railways that will never justify wires means batteries would have to be exceptionally large to cover the out and back range required. It would make sense where there is a logical group of similar services to justify sharing a single fuelling point at a centrally located depot from which all diagrams can be based. Examples could be Highland group based at Inverness covering Far North, Kyle. Borders/Cumbria group based at Carlisle. West and Central Wales based at Swansea.

 

[johnnychips]

Would it not be easier to say that the amount of diesel used on branch lines is really insignificant on the global scale and concentrate our efforts on electrifying the main lines?

 

[MarkyT]

Would it not be easier to say that the amount of diesel used on branch lines is really insignificant on the global scale and concentrate our efforts on electrifying the main lines?

A fair point globally but not for local emissions in areas where the remaining diesel trains would run. If diesel-only trains remained on the Buxton line, that would mean diesel emissions continuing perpetually all the way into central Manchester. Battery enhanced electric trains should be highly competitive with diesel bi-modes on suitable diagrams, should be cheaper to maintain, and will not have to visit fuelling points periodically, recharging enroute when under the wires of their partly electrified routes. Use of battery tech on branches does not detract from mainline electrification, rather it strengthens the case for such wiring and running through trains from the mainlines onto the branches.

 

[py_megapixel]

Would it not be easier to say that the amount of diesel used on branch lines is really insignificant on the global scale and concentrate our efforts on electrifying the main lines?

No, because a substantial amount of diesel is used on electrified main lines because of a lack of electrification of the branch lines they are going to serve.

 

[DynamicSpirit]

A fair point globally but not for local emissions in areas where the remaining diesel trains would run. If diesel-only trains remained on the Buxton line, that would mean diesel emissions continuing perpetually all the way into central Manchester.

Presumably diesel emissions in Manchester could be solved with conventional bi-modes, without any requirement for batteries, although they would still have your other disadvantage of requiring trips to be refuelled. And they'd still cause emissions at the Buxton end - I suspect that's not as serious an issue as at the Manchester end though.

(Don't get me wrong, if battery technology is mature enough to use, then I'm all for doing it to get rid of diesel emissions - especially if it results in quieter/more comfortable/better-accelerating trains. Just trying to tease out all the possible advantages and disadvantages).

 

[DynamicSpirit]

They're not green to make, I'll give you that. But the fleet wouldn't actually be that small.

A round trip on the Buxton line is about 2 hours 5 minutes depending on the time of day; some adjustments and the introduction of faster accelerating trains might be able to bring that down to 2 hours so we'll go with that for simplicity.
Add an hour to allow for turnarounds at each end and that's 3 hours. To provide a frequency of every 30 minutes you would need an absolute minimum of 6 units, but in reality the turnarounds might well be longer, the units aren't going to be in service 100% of the time and there are extra services in the peak, so you might want 10 units for that line.
Add however many are needed for Windermere factoring in the occasional airport service (4 units I think they said?) and you already have a fleet of 14. That is already more than the planned fleet of bimode 319s (769s) which would be the alternative solution other than continuing to run it DMU.

Not disagreeing with any of that logic, but one other consideration that might be important is that, if you have small fleet of battery-bi-modes just for Buxton and Windermere, while keeping diesel for the other non-electrified routes, doesn't that lose you some operational and timetabling flexibility? For example, perhaps, in some future timetable recast, you couldj have made Buxton fleet utilisation more efficient by having an incoming train from Buxton head off somewhere else (Northwich?) when it reaches Piccadilly thereby removing the need for a long layover at Buxton. But the two routes are operated by different stock, you lose that possibility.

(To be clear, I've no idea whether Buxton-Manchester then Manchester-Northwich is a practical possibiity in timetabling terms, and I wouldn't be at all surprised if it isn't - I'm just using that as an example to illustrate the general principle).

 

[py_megapixel]

Not disagreeing with any of that logic, but one other consideration that might be important is that, if you have small fleet of battery-bi-modes just for Buxton and Windermere, while keeping diesel for the other non-electrified routes, doesn't that lose you some operational and timetabling flexibility? For example, perhaps, in some future timetable recast, you couldj have made Buxton fleet utilisation more efficient by having an incoming train from Buxton head off somewhere else (Northwich?) when it reaches Piccadilly thereby removing the need for a long layover at Buxton. But the two routes are operated by different stock, you lose that possibility.

That's an interesting point, and I don't believe battery tech is quite mature enough for some of the other lines out of Piccadilly, particularly the Hope Valley and Mid Cheshire lines, and if that is something that would make sense to do then diesel-electric bimodes might make more sense.

At first I thought maybe it could head off somewhere electrified, but that would require far more battery stock. Though, it might be beneficial for charging the batteries up!

 

[MarkyT]

That's an interesting point, and I don't believe battery tech is quite mature enough for some of the other lines out of Piccadilly, particularly the Hope Valley and Mid Cheshire lines, and if that is something that would make sense to do then diesel-electric bimodes might make more sense.

At first I thought maybe it could head off somewhere electrified, but that would require far more battery stock. Though, it might be beneficial for charging the batteries up!

For mid Cheshire, say, look at how much discontinuous wiring you might add to make it viable on the same sized battery as required for Buxton. A bit extending from Stockport towards Altrincham, perhaps shared with Metrolink tram trains, then maybe a bit around Northwich fed from the WCML supply. A 'plug in' DC facility at Chester, fed off the Merseyrail supply for emergencies or for planned longer layovers.