I wonder what the impact of very fast charging has on the life of the battery and the capacity to hold a charge as the battery ages?

super fast charging (or discharging) is where the super-capacitor battery shared metal plate hybrid devices come in -  the capacitor charges at a few kA, but then in slower time (probably after disconnection while you are driving away) the chemical changes take place while  the capacitor part charges the battery part.

Right now the best we can do is cool conventional  cells so they do not boil (and explode) during high current flow, and it  is this thermal consideration that drives the designers to use so many small cells with coolant flow between them, instead of fewer bigger cells.

In terms of battery life, apart from temperature management, the most useful thing that you can do for Lithium-ion chemistry to prolong the life is not to push for the last amp hour and go hard up to 4.2V per cell, but knock of charging nearer 4.0V/cell - you still get 80% of capacity but this multiplies the lifespan in charge cycles many fold.

M

Interesting reading the replies on this, I think there is simplicity and something to be said for a empty steel tank in a vehicle that one pours/pumps liquid fuel into, or liquified gas!! and when it comes to recycling, degass the tank, flatten it and melt down and recycle into something new!!


GTB

Ultra fast EV charging points with a capacity of approaching 1 Mw are entirely doable, but will need a very substantial power supply to the service station or other facility.

I doubt that a large number of such charging places will be needed. Comparisons with petrol filling rates are not valid. Almost all petrol is obtained from filling stations, which must therefore have enough petrol storage capacity and a high enough flow rate to meet this demand.


Most EV charging will at home or in workplace car parks, and relatively simple to supply. I would expect that most car trips would be completed within the capacity of the battery charged at home.

Ultra fast charging at filling stations will only be needed for a very small proportion of charging needs.


And for a number of ultra fast charging places, you do not  need to allow for the simultaneous maximum demand of each. Some spaces will be taken by cars still being manouvered into place, connected up, and awaiting payment authorisation. Other spaces will be taken by vehicles that are nearly full and completing charging at a lower rate. Still other places will be taken by vehicles that have completed charging, but not yet driven away because the driver is still in the shop or toilet.


A 20 MVA transformer could probably supply at least 40 charging places each of 1 Mw.


Consider the following charging cycle.

1) Driver observes empty charging slot and parks in it, 30 seconds.

2) Connects charging lead, 30 seconds.

3) Inserts payment card and awaits authorisation, 60 seconds.

4) Charging at 1 Mw for three minutes as battery not empty.

5) After charging complete, vehicle occupies space for another 120 seconds as driver still in shop or toilrt.

6) Driver returns to vehicle and unplugs charging lead, 30 seconds.

7) Drives away, 30 seconds until space free for another customer.


A total of about 8 minutes, during which the 1 Mw load is only demanded for about 3 minutes.

It would be prudent to fit some form of monitoring and controll unit that limits the load on the 20 MVA transformer to say 22 MVA short term. In the unlikely event that 22 places were each using 1 Mw, then the 23rd vehicle to arrive could park, connect up, authorise payment, but charging would not start until another vehicle had finished. With an average charge time of say 4 minutes it would on average be only a few seconds until one of the 22 already charging vehicles was done.

Broadage,

Ok a 20MVA  substation and the charging units themselves, cost to procure and install 20MVA substation, LV Panels and the charging cabinets and charging units, all the civil and electrical installation work and ongoing maintenance involved presuming that the local DNO/IDNO has a spare 20MVA just lying about.


Ever wondered what the "Purchase" price would have to be per unit of electricity for the EV driver/customer that the buisness entity would then make a suitable commercial return for their investment that built and installed and runs the EV charging hub.


Advancing technology and engineering is all very well and great and of course I support that, but it comes at a cost and the vast masses of people dont want to pay for that development nor indeed new technolgy when it first arrives, sometimes as engineers we can do things that are great, but if nobody wants the product or technology or its too expensive from what they already pay what was the point.

Look back to introduction of the video recorder and Sony Betamax, VHS and even Philips 2000, everybody new which one offerred the better audio/video experience but where did things settle out for the masses globally?


HM Treasury are already forecasting loss of revenue of fuel duty and they will want that money to come from the motorist in another form. That could be a tax on electricity used to charge EV's or as many suspect will be a charge per mile scheme based on usage and using national network of ANPR cameras. EV users think at this time running costs are low, but will not be that way for ever.


How often does a consumer by a brand new car? In fact majority of people by second hand cars and average time for keeping a car before buying another. Even if you could get battery technology and chargers to speed charge at same rate to put liquid fuel in a car, what about all the existing EV cars with older battery technology they wont get the benefit of the faster charging times. Thats the issue we have with the existing fast chargers not every car can charge at those speeds.


I do think some people are rather like rabbits in a cars headlights with EV cars and chargers they just cant see, cant see where they are going and dont know unfortunately whats about to hit them.


GTB

Some excellent points there, GTB!


70 kWh at home, about £12.50. At the InstaVolt chargers, £25. Double on a motorway? £50 - may be a little more than the equivalent range on diesel. Double again for super-fast? So do you opt for a 30 - 40 minute break and spend £50 or do you fill up in just enough time to go for a pee and spend £100? I guess that it will depend upon who is paying.


I cannot help feeling that this is a solution without a problem. ?

This is not practical at all, because a suitable connector and cables for 1MVA would not be able to be lifted by the average member of the public. The chemical reaction needed to store this energy is also extremely dangerous, it would need a 1MVA electronic converter as charge controller with an efficiency of 95% if you are lucky, so a way of dissipating 50 kW. This is going to be a hot little filling station. The capital cost would also be very high, much more than a few tanks and pipes.  Ah, I know various people are trying contactless charging you say, but at this power level that is going to be even more expensive. Charging the battery is going to make it also have a great deal of heat to dissipate somehow, probably 100kW, so you again have a huge heat problem, which electric vehicles already have during discharge but at a much lower level.


The biggest snag is that we don't have the electricity, of course, so add the cost of a few nuclear power stations to the bill and electric cars are simply not an economic proposition, and presently receive a ridiculous level of subsidy from the rest of us, the magnitude of which has yet to be appreciated. Germany is trying renewables quite hard and now has the most expensive electricity in the World, they are deciding to build more coal-powered stations as a backup to the unreliables. One cannot make it up.

It has also taken 120 years to get to the present designs, that's a very long time, although most of the fancy stuff has been the last 40 years. The timeline now is not really even 20 years apart from milk floats and fork trucks, which really are not car prototypes.

Lithium batteries tech is very young. Lead Acid chemistry gives 1.2V per cell and requires smart conditioning to stop early death from over and under charging.