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Discussion Starter #1

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Also the analogy with aircraft is flawed as most air to air is military and based around the fact that a plane can fly with approximately 40% greater mass than it can take off with.
Also, there’s a reason why civil flights don’t do this. :)
 

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Very imaginative! One for the Sci-Fi movies, I'd say.

A method of transferring charge between EVs while stationary would save a whole lot of hanging about and flat-bed journeys

Jump leads anyone?
 

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Very imaginative! One for the Sci-Fi movies, I'd say.

A method of transferring charge between EVs while stationary would save a whole lot of hanging about and flat-bed journeys

Jump leads anyone?
That explains why everyone drives around with a piece of hose in their car. ;)
 

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Discussion Starter #5 (Edited)
V2V is already possible on Chademo, just not yet on the stupid CCS forced on us by the EU.
(I'm still waiting for a response from @Rei ;) )
 

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Discussion Starter #6
That explains why everyone drives around with a piece of hose in their car. ;)
Strangely since they put ethanol in petrol I do in one of my ICE. :eek:





Only because the ethanol goes off and blocks the fuel line, and I have to blow it back into the tank. Honest, Officer.
 

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V2V is already possible on Chademo, just not yet on the stupid CCS forced on us by the EU.
(I'm still waiting for a response from @Rei ;) )
How prey tell does Vehicle to Vehicle charging via Chademo work ? Vehicle to grid, yes, Vehicle to Vehicle ? No. Not with current cars AFAIK.

All Chademo cars that I'm aware of simply connect the battery directly to the DC pins on the Chademo port via contactors when charging is active - there is no electronics interposed between the Chademo connector and battery, just the contactors.

If both cars have this standard configuration you can't simply conect them together and close the contactors, especially if the two cars are different models with different pack voltages for the same SoC or even just the same model of car at different states of charge.

Out of necessity the car providing the power has to be able to output a higher voltage than the voltage of the pack in the receiving car, over the range of SoC required during the transfer, (sending car SoC dropping, receiving car SoC rising) and the current needs to be regulated to a safe level as dictated by the limits of both cars, but minimising losses while doing so.

This voltage step up and current regulation means interposing fairly complex high power electronics between the two batteries, and for practical reasons like backward compatibility this would have to be in the donor car.

One of the major benefits of DC rapid charging over AC is that the high power electronics needed to charge at say 50kW don't have to be in the car itself saving cost, weight and space in the car. To provide DC vehicle to vehicle charging you're essentially putting that costly, heavy, large power electronics (and necessary cooling system) back into the car for the very rare occasion where you might want to give someone a top up on the side of the road - eg almost never. Worse still you need additional contactors to switch it into circuit.

So while it's technically possible to implement and may even be in the spec (I haven't looked) I very much doubt we'll see it in any normal cars for cost reasons - it adds significant cost and complexity to a car for the very rare occasion that you might use it to help someone out.

On the other hand it makes a lot of sense for a recovery vehicle to be able to donate some of its charge to a stranded vehicle, and very quickly. Being able to give a stranded EV a 10 minute rapid charge to give it enough charge to get to the next charger makes a lot more sense than the 3kW AC that some recovery vehicles have now - which is more or less useless as it's too slow.

It's likely that recovery vehicles will have a dedicated outlet to do this rather than sharing the normal rapid charging socket though.
 

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Discussion Starter #8 (Edited)
I agree that you cannot just connect the batteries together and need some complicated high voltage power electronics in between. But that hasn't stopped Hyundai demonstrating it:





I do have to withdraw my cheeky swipe at CCS earlier as this is using that system. ;)

It'll be interesting to see if this takes off, and whether roadside assistance companies choose to hardwire the device or like this use the existing port.

It looks like Hyundai have used it in India to provide some confidence against range anxiety in a desert of rapid charging points.


Hyundai introduces Vehicle to Vehicle charging facility
 
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