New trains from old?

[whole diary]

[grahame]

Would Bedford - Bletchley be in range?  That was/is supposed to be getting 3 x 230s according to earlier plans by the new TOC^▸ (Train Operating Company)?  I had assumed they’d be diesel though...

Paul

I think that plan went up in smoke, since diesel 230s will no longer be available in time for the new franchise. And it's not 3rd rail territory, is it?

There were various stock plans floating around ... a chance meeting with one of the key people involved in stock resourcing as one franchise moved to another would suggest that the was not completeness or certainly in any of the plans ...

Seriously bad following up my own post with contradictory evidence ... a couple of weeks old but the Bedford to Bletchley line users association write on their Facebook page after a visit to Long Marston earlier this month

The team at Vivarail are an enthusiastic and dedicated bunch and they and our hosts wmtrains made us very welcome.

Our units will have 6 to 8 full width tables with a remainder of airline and tip up style seats to enable bicycle storage. There will also be shared space which can be used for cycles buggies and wheelchairs total 108 seats. We emphasised the need for luggage space and bins for waste; the location of these is still to be decided. We also confirmed the need for onboard ramps which had been missed. Trains will have anti slip protection, sanders and drive through all bogie wheels.

[TonyK]

And as for their charging points, if they need to be installed in several stations in less than six months, with their feed at 11 kV or more ... sound likely?

Doesn't sound at all likely. That means you would be limited to a trial involving a branch line of a length that would match the capacity of the batteries and fit the kit in just one station. You could do that at Temple Meads for the Severn Beach line (26 miles the round trip) but you reduce that to a shuttle service and spoil the diagrams that extend beyond BRI^» (Bristol Temple Meads - next trains).

[grahame]

And as for their charging points, if they need to be installed in several stations in less than six months, with their feed at 11 kV or more ... sound likely?

Doesn't sound at all likely. That means you would be limited to a trial involving a branch line of a length that would match the capacity of the batteries and fit the kit in just one station. You could do that at Temple Meads for the Severn Beach line (26 miles the round trip) but you reduce that to a shuttle service and spoil the diagrams that extend beyond BRI^» (Bristol Temple Meads - next trains).

Interesting, I gave that some thought and came up with around a dozen services in our area or close by that would be candidates.  Two or three are innovative (for example Swanage to Wareham and Honeybourne to Long Marston), two or three would really upset the current user or advocate base, but the majority would be operationally and politically in spec.

[IndustryInsider]

Lots of potential candidates throughout Britain, should any initial trials go well.

[broadgage]

Charging only at stations should be doable.
I doubt that an 11KV supply would be needed for these relatively short range and lightweight units.
A 3 phase 100 amp supply at 230/400* volts should do. After losses that would be about 70KW* into the battery.

A short length of conductor rail would be the obvious means of charging. Although the health and safety industry are opposed to new conductor rail installations, this could be made much safer by only energising the rail when a train was either over it, or so close that being run over was the greater risk.

*presuming that the nominal 400 volt supply is in fact a bit higher than 400 volts, most are nearer 420 volts.

[TonyK]

Another question that needs to be answered is exactly how many different types of motive technology we really want. As things seem to be progressing, we could conceivably end up with a station having overhead and third rail electrification, hydrogen and diesel refuelling systems on hand, with class 139s running a shuttle service to somewhere not far away.

[stuving]

Charging only at stations should be doable.
I doubt that an 11KV supply would be needed for these relatively short range and lightweight units.
A 3 phase 100 amp supply at 230/400* volts should do. After losses that would be about 70KW* into the battery.

A short length of conductor rail would be the obvious means of charging. Although the health and safety industry are opposed to new conductor rail installations, this could be made much safer by only energising the rail when a train was either over it, or so close that being run over was the greater risk.

*presuming that the nominal 400 volt supply is in fact a bit higher than 400 volts, most are nearer 420 volts.

There's a lot of (unknown to us) factors that go into the range and recharging calculations, but some of them are given by Vivarail. However, I can't work out what 40 miles with 8 minute charge each end or 50 milles with 10 minutes means in terms of power or energy. The two-car train has four 100 kWhr batteries, so a full recharge in 10 minutes  would need over 600 kW* 2.4 MW.

Of course you would not reckon on a full recharge, and there's trade-offs between turn-round time, range, and battery weight, but it's still a bit mysterious. Mind you, I just read what Vivarail say:

The charging point can draw power from existing infrastructure – it simply needs an electrical supply of 11kV or 33kV.

However if the supply is not strong enough then a static battery bank can be used instead to provide an energy reserve at the charging points.  Vivarail is spearheading this design for the rail industry but it is already used in other applications – such as motorway service area electric car charging.

* True as written, but truer is better.

[broadgage]

As a full charge in 10 minutes is said to need over 600KW, then that to me suggests a 70KW supply would fully charge the battery in about 100 minutes, or say at 1% a minute.
But surely they are not reckoning on fully discharging the battery every trip ? So a partial charge during each layover and a full charge at night might suffice.

OTOH^▸ (On The Other Hand), they state four batteries with a total capacity of 400KWH, to fully charge that in 10 minutes would take about 2.6MW (allowing an estimate for losses in battery and in the charger) which is beyond any reasonable supply at 230/400 volts, and borderline for 11KV.

So perhaps they mean a total battery capacity of 400KWH, with about one fifth of that capacity used per trip. If 80KWH is used per trip, then to replace that 80KWH in 10 minutes would need 480KW without any losses, and perhaps 530KW with losses, or about the stated 600KW with some pre heating of the passenger saloon.
600KW is excessive at low voltage but readily available from an 11KV supply, though 33KV might be preferred for such a disturbing load.

More confirmed detail needed, in particular total battery capacity, and the capacity used per single or return trip.

[JayMac]

Or just admit that Vivarail are flying kites with no real prospect of finding widespread users for their speculative punt on the D78 stock.

[ChrisB]

I'm sure Vivarail, and Adrian Shooter - have checked out everything battery & charging-wise & are happy with their research & development. I certainly respect them & if they're happy I think we don't need to query this, especially until we have full facts which I'm sure will be available to anyone emailing & asking.

[stuving]

More confirmed detail needed, in particular total battery capacity, and the capacity used per single or return trip.

I did, I think, distinguish Vivarail's data from my sums (which are not guaranteed error-free), and their data are all accessible. The battery capacity they do quote as 106 kWhr and on one of those videos as 90 kWhr, but I take that to be two different ways of rating a battery.

In any case we are not reckoning to that sort of accuracy. The two biggest unknowns - unknown by far more than that - are the real-world ones: how much power it will need for particular route, and how much charge needs to be kept in reserve "just in case". It is awfully embarrassing to run out, after all. If fast charging causes battery degradation then that would become a constraint you would need to factor in too.

[JayMac]

I'm sure Vivarail, and Adrian Shooter - have checked out everything battery & charging-wise & are happy with their research & development. I certainly respect them & if they're happy I think we don't need to query this, especially until we have full facts which I'm sure will be available to anyone emailing & asking.

I prefer blind cynicism to blind faith.

[broadgage]

Presuming that these battery units work as intended, they might be attractive to heritage or preserved railways that wish to run economical commuter services outside of their steam operating season.

Clean, green, near silent, and possibly also attractive to some enthusiasts for the novelty value. The limited seating capacity should be of little concern, if the passenger numbers are likely to exceed this capacity then running a steamer or heritage diesel starts to look more viable.

[lympstone_commuter]

I wonder if a key point here is the suggested use of a large 'battery bank' at each charging location, rather than charging the trains 'directly from the mains'? This would cut down on the need for an expensively beefy electrical supply to charging points.

(the idea of a 'battery bank' is mentioned towards the end of Geoff Marshall's video: https://www.youtube.com/watch?v=SnNaMPR-e1I )

Presumably this means an array of [stationary] batteries at the charging locations which are "trickle" charged continuously (or perhaps charged at night when electricity is cheaper). The battery bank would then discharge (into the train batteries) at a much higher rate, during the relatively short periods when trains are stationary at the terminus and connected via 3rd rail / OHLE.

A domestic supply can (I think) provide around 25kW in total so accumulating 400kWhr in a battery bank over the course of a day would be quite feasible with just a standard domestic supply.

How quickly could the battery bank charge the train's batteries? I don't know if the limiting factor here is the batteries or the 3rd rail / OHLE, but given that power ratings for trains are in the several MW ball park, charging the train at up to 1 - 2 MW sounds reasonable (if the batteries can take it). This would suggest that a *full* recharge (of 400kWhr batteries at a rate of over 1MW) in under 15 minutes is not unreasonable.

The key ratio would be the fraction of each day in which the battery bank was discharging into a train - i.e. the proportion of the time that a train was present in the terminus. For 2tph with a 3 minute layover this would be 6 minutes per hour or 1/10. This would mean the battery bank could be recharged using 10% of the current at which it is discharged.

No idea if this argument is correct but it seems plausible to me!

[ChrisB]

8 mins quoted to recharge batteries in that video