Merseyrail Class 777 introduction updates

[alf]

I am not sure Energy is right.

Does he really mean “with greater current comes greater resistance..”
Doesn’t he mean by “resistance” ‘greater power loss across the batteries’, which is current squared x voltage.

On dc circuits, like the one across batteries in series, my Physics A level course (which got me into university very very many years ago) told me resistance for a length of wire or a battery is a fixed value independent of current or voltage.
Indeed it is the fixed value of the resistance that determines the relationship between Current & volts. (V= iR. or I= V/R)

It would help me & others if Energy could explain if & how I am wrong!

 

[Nicholas Lewis]

The battery chemistry on an EV is different to that of a train.

EVs generally use Li-ion chemistries that are designed to maximise range while taking into account that the average car spends most of its time stationary. The volume and mass considerations are also somewhat different.

As far as I know, Stadler use LTO chemistries for their battery packs, which have a slightly lower energy density, but cope far better with being constantly charged and discharged at high rates, such as during regenerative braking or during acceleration.

As you say LTO chemistry delivers much higher discharge/recharge rates than Lithium-Ion potentially upto six times rated power which as you say makes them far more suitable to rail traction duty especially metro with its frequent high acceleration braking duty cycle (recuperation). They also operate effectively over a much wider temperature range which is key requirement as well as having a much longer life if you measure it by number of charge/discharge cycles before degradation occurs and a much reduced fire risk compared to car battery chemistry. However, the penalty is much less power by volume and weight hence the weight of the batteries in a 777. Also we have to note that batteries are made of 100's of individual cells nominally 2.4V for LTO so if you want say 600V for the traction inverters you need 250 in series and then depending on the energy capacity of the cells you would need multiple strings in parallel to achieve the nominal 160kwh being installed under each carriage. In a traction battery they will package up the cells into modules then assemble the modules into the rafts installed under each carriage.

 

[Energy]

I am not sure Energy is right.

Does he really mean “with greater current comes greater resistance..”
Doesn’t he mean by “resistance” ‘greater power loss across the batteries’, which is current squared x voltage.

On dc circuits, like the one across batteries in series, my Physics A level course (which got me into university very very many years ago) told me resistance for a length of wire or a battery is a fixed value independent of current or voltage.
Indeed it is the fixed value of the resistance that determines the relationship between Current & volts. (V= iR. or I= V/R)

It would help me & others if Energy could explain if & how I am wrong!

I thought about V=IR and thought I'd got something wrong but knew that higher voltage is more efficient, your correct that I meant power loss instead which does decrease with greater voltage and I've updated my post, thanks.

The loses will be small compared to dc to dc conversion so the battery will likely be configured to the bus voltage.

 

[DavidPowell]

That seems like a very heavy battery. That's roughly 6 times the battery in an average EV car, in terms of kWh, and they certainly don't weigh a tonne! The 55kWh battery option in the VW ID.3 weighs 206kg.

Is the battery chemistry different from the Lithium Ion batteries used in most EVs?

As you say LTO chemistry delivers much higher discharge/recharge rates than Lithium-Ion potentially upto six times rated power which as you say makes them far more suitable to rail traction duty especially metro with its frequent high acceleration braking duty cycle (recuperation). They also operate effectively over a much wider temperature range which is key requirement as well as having a much longer life if you measure it by number of charge/discharge cycles before degradation occurs and a much reduced fire risk compared to car battery chemistry. However, the penalty is much less power by volume and weight hence the weight of the batteries in a 777. Also we have to note that batteries are made of 100's of individual cells nominally 2.4V for LTO so if you want say 600V for the traction inverters you need 250 in series and then depending on the energy capacity of the cells you would need multiple strings in parallel to achieve the nominal 160kwh being installed under each carriage. In a traction battery they will package up the cells into modules then assemble the modules into the rafts installed under each carriage.

Really interesting discussion about batteries with a bit of physics thrown in.

The Class 777 IPEMU uses LTO batteries as some have correctly identified. These give a good combination of energy and power density and have an inherent resistance to thermal runaway (aka catching fire if it goes unchecked).

I have always found comparisons with automotive applications misleading and ultimately unhelpful as the duty cycle is completely different. A car typically sits idle for over 23 hours a day whereas a train is typically in use for at least 12 hours a day.

The key to the business case has been gaining confidence in the anticipated battery life while still delivering good performance even as the battery inevitably degrades. The 777 is a powerful machine with metro train acceleration which we can replicate with the batteries. The key to good battery life looks to be good cooling and basically being relatively “gentle” electrically. Stadler are undertaking the type tests at Wildenrath in Germany at the moment: so far so good.

 

[Parjon]

The key to the business case has been gaining confidence in the anticipated battery life while still delivering good performance even as the battery inevitably degrades. The 777 is a powerful machine with metro train acceleration which we can replicate with the batteries. The key to good battery life looks to be good cooling and basically being relatively “gentle” electrically. Stadler are undertaking the type tests at Wildenrath in Germany at the moment: so far so good.

Given the cost of the batteries and the need to replace them at some point, over say 50 years what do you reckon is the expenditure difference between 3rd rail extension versus IPEMU? Assuming for this purpose the batteries work and that they are used to get to Helsby from ePort.

 

[Nicholas Lewis]

Really interesting discussion about batteries with a bit of physics thrown in.

The Class 777 IPEMU uses LTO batteries as some have correctly identified. These give a good combination of energy and power density and have an inherent resistance to thermal runaway (aka catching fire if it goes unchecked).

I have always found comparisons with automotive applications misleading and ultimately unhelpful as the duty cycle is completely different. A car typically sits idle for over 23 hours a day whereas a train is typically in use for at least 12 hours a day.

The key to the business case has been gaining confidence in the anticipated battery life while still delivering good performance even as the battery inevitably degrades. The 777 is a powerful machine with metro train acceleration which we can replicate with the batteries. The key to good battery life looks to be good cooling and basically being relatively “gentle” electrically. Stadler are undertaking the type tests at Wildenrath in Germany at the moment: so far so good.

@DavidPowell thanks for confirming they are LTO batteries and contributing to this debate with technical information about this exciting new opportunity that these trains will offer and I do hope you are able to quickly push the beyond the Merseyrail boundaries to exploit the BEMU capability.

If i may ask is the intention to have the battery supporting acceleration when running on third rail so you can maximise energy recovery during braking (recuperation) or does your modelling show that the network will be sufficiently receptive to achieving high levels of regeneration to achieve overall lowest energy consumption without over cycling the batteries.

Also there has been a habit in the UK over many decades now not to exploit the installed power in new trains to tighten up schedules and thus often trains are driven to the power envelope using more energy then sit at stations waiting time ie they consume more energy than necessary to achieve the SRTs - will Merseyrail amend the SRTs or provide driver advice to minimise energy consumption.

 

[Skie]

Also there has been a habit in the UK over many decades now not to exploit the installed power in new trains

On one hand the sensible policy of not accelerating so quickly you tip all of the old dears over (going twirlie* bowling) or cause excessive rail/wheel wear is sensible. On the other, inflexible Professional driving policies implemented to save energy/fuel at the expense of everything else are monumentally stupid.

There is a balance, and I’m sure they’ll find it.

*Twirlies is scouse parlance for those with concessionary passes who arrive before they are valid after the morning peak. “Too earlies”

 

[Bletchleyite]

On one hand the sensible policy of not accelerating so quickly you tip all of the old dears over (going twirlie* bowling) or cause excessive rail/wheel wear is sensible. On the other, inflexible Professional driving policies implemented to save energy/fuel at the expense of everything else are monumentally stupid.

I was quite surprised to read on here that drivers generally set (and are allowed to set) the Class 195 to "performance" mode, as a result of which that's the normal setting, to be honest...

 

[Peter Sarf]

I was quite surprised to read on here that drivers generally set (and are allowed to set) the Class 195 to "performance" mode, as a result of which that's the normal setting, to be honest...

I wonder if that is because, unlike You or I, they do not pay for the fuel they use !.

 

[507020]

I was quite surprised to read on here that drivers generally set (and are allowed to set) the Class 195 to "performance" mode, as a result of which that's the normal setting, to be honest...

What is the other mode? It was certainly surprising seeing my bottle of water fall off the table and roll half way down the carriage when leaving Deansgate on a 331! The 777s not having tables might be spared this problem, but passengers definitely won’t be spared their full acceleration, except perhaps when leaving Headbolt Lane.

 

[Nicholas Lewis]

I wonder if that is because, unlike You or I, they do not pay for the fuel they use !.

If the schedules are timed to SRT using performance mode then they won't be wasting energy although in my experience in my area most drivers know when to shut off and coast. If anything id say more energy is wasted being bought to an unnecessary stand at reds although its easy to blame signallers too many areas lack ARS even in recently resignalled areas as NR committed to traffic management systems which were going to deliver that functionality them largely parked them other than a few Luninate systems.

 

[MattRat]

I wonder if that is because, unlike You or I, they do not pay for the fuel they use !.

Or it could be to keep to schedule/the units are underpowered.

 

[Peter Sarf]

Or it could be to keep to schedule/the units are underpowered.

Not sure I am surprised if that is the case !.

 

[Sam 76]

Does anyone know the test pattern for the 777s on the Kirkby line presumably starting today ?

 

[karlbbb]

I would guess that the "skipped" services will be where the 777 could potentially run. Looking at the amended timetable there is an alternating 15/30 minute gap between services, so at a guess the "missing" 15 minute service seems a gap that would be the simplest to use.

(I also forgot about the timetable change and wondered why so many people got on my train from Ormskirk at Kirkdale)

 

[Skie]

They’re on real-time trains

Realtime Trains | Departures from Kirkby between 0600 and 2000 on 14/11/2022

Train information at Kirkby between 0600 and 2000 on 14/11/2022. From Realtime Trains, an independent source of train running info for Great Britain.

www.realtimetrains.co.uk

 

[Sam 76]

They’re on real-time trains

Realtime Trains | Departures from Kirkby between 0600 and 2000 on 14/11/2022

Train information at Kirkby between 0600 and 2000 on 14/11/2022. From Realtime Trains, an independent source of train running info for Great Britain.

www.realtimetrains.co.uk

Thanks so much for this

 

[DavidPowell]

Thanks for the various questions in the posts above.

1. Cost difference of 3rd rail vs IPEMU. We have modelled this on a few routes over a 35 year life cycle. The saving provided by IPEMU gets bigger for longer routes. A typical saving will be measured in tens of millions of pounds.

2. Regenerative braking. The 777s will regen and the substations have been modified to enable this. However we anticipate that the receptivity will be hit and miss on most of the network. The batteries will therefore help us to recycle braking energy.

3. SRTs (Sectional Run Times). The 777s deliver significantly reduced SRTs across the network. However we won’t be able to take full advantage of this until the 507/8s have been fully withdrawn from service.

4. The key to not knocking standing passengers over is to control what’s known as the jerk rate (yes I know!) which is the rate of change of acceleration measured in metres per second cubed. The 777s do this well: the high power and braking forces are applied very smoothly.

 

[karlbbb]

One for the drivers (and maybe David) - with the 777s now having variable brake and power applications, do drivers keep the same brake points? I assume the brake points are generally based on an average deceleration rate given by each stage of brake on the 507/508s. Do the 777s have some form of indicator to show power/brake applications as a % (or something along those lines) that would ease that transition or will it all be down to the driver to accurately choose their brake application rates?

I can see the new trains on the ECS runs from my work window, really looking forward to getting on them for real.

 

[LPJOHN]

Last week the train I was on came to halt just before Sandhills because of a trespasser being on the line at Bootle, the power was switched off for about 15 minutes. And I got to wondering if the shunting batteries are powerful enough to move the train to the nearest station.

Does anyone know if this would be possible?

 

[Skie]

Last week the train I was on came to halt just before Sandhills because of a trespasser being on the line at Bootle, the power was switched off for about 15 minutes. And I got to wondering if the shunting batteries are powerful enough to move the train to the nearest station.

Does anyone know if this would be possible?

It’s possible if the distance is very short, but it would be unlikely to be used with a trespasser due to the risks involved.

 

[MattRat]

It’s possible if the distance is very short, but it would be unlikely to be used with a trespasser due to the risks involved.

It would, however, be able to keep the train powered, so you don't lose, light, heat, etc.

 

[Sam 76]

Has there been any concrete answer on whether the deal went through to allow driver training ?

 

[jamesst]

Has there been any concrete answer on whether the deal went through to allow driver training ?

No it didn't

 

[TT-ONR-NRN]

They’re on real-time trains

Realtime Trains | Departures from Kirkby between 0600 and 2000 on 14/11/2022

Train information at Kirkby between 0600 and 2000 on 14/11/2022. From Realtime Trains, an independent source of train running info for Great Britain.

www.realtimetrains.co.uk

Shows a three hour gap between departures!

 

[Skie]

Shows a three hour gap between departures!

There is a gap at lunchtime but it completes multiple round trips in the morning and afternoon.

 

[TT-ONR-NRN]

There is a gap at lunchtime but it completes multiple round trips in the morning and afternoon.

Oh - I do beg your pardon, I see you filtered on "Non-passenger!" I thought it was showing all services.
I was going to say, a reduction is service from 4tph to 2tph is alright I guess, but a four hour gap between services is abysmal!

S.T.S.

 

[ExRes]

Looks like the possibility of a move on Tuesday/Wednesday, 1046 6Z43 Tyseley Steam Trust to Crewe CS and 2230 5Q44 Crewe Down Refuge to Kirkdale CS, all the time in the world for cancellation of course but with the headcode and the fact that two of the Class 20s are working Peak Forest the RA 43s could well be getting some work

 

[8A Rail]

No it didn't

Appreciate the info. Are ASLEF And Merseytravel attempting to keep this rejection quiet as it don't seem to be picked up by the media? So I guess no Class 777's entering traffic this year then!

 

[Pacef8]

Saw 3 777s at crew yesterday