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Super-fast EVCPs?

Chris Pearson
I don't think that I have seen this in here before, but these batteries came up in a motoring forum.


The claim to charge an EV all the way in 5 min seems to be entirely spurious - all that they have managed so far is a moped, but even if the batteries existed, how would they be charged?


Here is my back-of-a-fag-packet calculation. An average EV will do 4 - 5 miles per kWh; let's be conservative and say 4. So with a range of 300 miles between charges, that requires 75 kWh. Delivered over 1/12 hour that requires 900 kW. So in round terms, that is one 1 MVA transformer per EVCP. Could be useful on a motorway, but I cannot see the point elsewhere. Even then, very few journeys in UK are over 300 miles. Both Edinburgh and Land's End are closer to Birmingham than that.


900 kW at 48 V DC is almost 20,000 amps. What sort of connexion is envisaged?
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    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
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  • 0
    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
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