In another discussion on here a few months ago, somebody (replying to a point I had made about the cost of feeder stations) claimed that a mile of 25kV cable running on wooden poles across fields costs orders of magnitude less than electrifying a mile of railway.
So if you wanted to have a charging post at the terminus of a branch, perhaps you could feed it from the main line via such a connection without electrifying the branch.
You could run a 25kV supply (plus a -25kV ATF supply) on a wooden pole across a field, that's the least silly suggestion we've had when it comes to battery powered units, but there are issues with taking 25kV supplies outwith the railway, which would get expensive and complicated, with wayleaves to be agreed by the railway authority and the land owners.
The leasing charges for the battery pack are in the region of a 2 car DMU per month, and when you start adding in multiple diagrams and maintenance spares, adding together the costs of running 25kV to the end of a branch line, it all gets very expensive very quickly.
Furrer+Frey and Railbaar have been hawking around their quick charge stations now for a number of years, they're getting a bit of interest from bus companies but little interest from train companies and rolling stock builders.
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Realistically, it's cheaper to do a Paisley Canal and put up non-standard 25kV AC OHLE. Most of the costs of electrification will be in doing only a small number of things, such as rebuilding bridges or lowering tracks. If you're lucky, then any sections where it is impossible to have the overhead wires powered up will be short enough and in the right place for trains just to coast through. If not, then by fitting only a small fraction of the battery capacity that is needed for a proper IPEMU, you could have enough power to get a train moving. Even if there's only enough power and energy available to make a train trundle along at 20mph for a few hundred metres that would be enough to get through almost every forseeable obstacle to electrification on most branch lines. The 25kV feed can just be diverted to run through an insulated cable, so gaps in the powered OHLE won't require any extra feeder stations. If in future the line needs to be revisited to make the OHLE properly standards-compliant, e.g. for electric freight, then so be it.
Paisley Canal isn't non standard, it's essentially conventional BR Mark 3 OLE, the only change is that it's setup with a non standard wire height, there's nothing on the route which can't be converted to the normal wire height in due course, subsequent to bridge clearance, track lowering and platform height adjustments being carried out. That would, in turn, provide an electrified route through to the Hawkshead Oil Terminal (though it's not as yet wired, so shunting would be needed).
The components on the masts and portals would simply need adjusted to the corrected wire height, there's nothing that's set that actually limits the wire height.
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However it would still have to supply the maximum current that one train can take, so as to get the maximum charge into the battery. That is what determines the rating of the substation, give or take heating issues, even if it is only used for a few minutes each hour.
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Has anyone looked at whether there would be any saving if the current was limited to what one train could take, which would be a lot less than a standard feeder station? My gut feeling is "not much" but it would be good to know for sure!
The saving would be minimal, and provides absolutely no future proofing at all, if you're going to install feeders at the end of each branchline, common sense dictates you make sure they're sufficient to provide cross feeding in the event of an adjacent feeder failing, and have sufficient future proofing to cope with future traffic demands.
As I say, to rapidly charge battery packs up, you need to provide significant power, well in excess of what a single multiple unit would require if it was being fed via OLE. 8MW for a rapid charge of a 450kW battery pack isn't unreasonable if you want to charge it during a station stop.
The idea of more gently recharging over 30 minutes is fine, that only needs 900kW of power, but who is going to realistically diagram an expensive EMU with battery packs costing the equivalent of another EMU or DMU to sit for 30 minutes just to allow them to charge up ?
