New battery tech?

[Tim+]

Would be nice if some of this turned out to be true.

Tim

[Chris Hogg]

Interesting. I see they're claiming the battery will charge in minutes rather than hours.

Say a typical car petrol tank holds 12 gallons. 1 gallon of petrol has an energy equivalent of 33.4kWh

So a typical car petrol tank contains an energy equivalent of about

400kWh. If that were to be replaced by a battery storage system, which was wanted to be recharged in say 5 minutes (one twelfth of an hour), as is done now with a petrol filling system, that would require a power input of 4800kW (400x12). At 1000 amps that would be 4800 volts (assuming my logic and numbers are correct, which they may not be!).

I'd be interested to see the forecourt of the future!

But I imagine things would no longer be done that way. If those batteries are truly reliable, then an exchange system would probably be the way things would go. Or perhaps an induction system, where you just drive in, position your car over an induction plate and let it charge, with no electrical linkages at all.

[Caecilius]

Applying Betteridge's law of headlines, I guess the answer is likely to be "no".

[Chris Hogg]

Well, of course. That's what happens now, but the problem arises when you want to drive further than the capacity of your battery will allow, and you have to re-charge en route.

Car petrol engines around about 20% max, a bit more for diesel. Probably triple that for electric cars, so by implication only half the equivalent tank capacity needed. But that still leaves some pretty hefty amps/volts needed for charging. See

for some numbers.

[GB]

Surely, triple => one-third capacity needed?

If you add in that electric cars tend to have regenerative braking and so on, it gets better still.

One way petrol engines score is that they use waste heat for warming the passengers.

[newshound]

Interesting numbers.

Just for comparison, the biggest wind turbines are, I think, approaching

5 MW and their generator is probably bigger than a Transit van. A 5 MW marine diesel is getting on for the size of a shipping container. A 5 MW gas turbine is about the size of a car.

I don't know offhand the capacity of the 11kV and 33 kV power lines (the ones which are still on wooden poles). I guess a single 11kV line would probably service a multi-terminal garage OK.

[Dave Plowman (News)]

Except that a typical electric motor is miles more efficient than any IC one. Of course heating the car will increase energy consumption- that comes free with an IC engine.

[GB]

Electric motors produce heat, too, but not nearly as much.

[Chris Hogg]

Yes, absolutely correct. The initial figures I found suggested a factor of two difference, but later I found the factor of three, but I omitted to correct that bit.

[Andy Burns]

Several manufacturers seem to have 8MW monsters now

[GB]

Sorry to be pedantic. :)

Anyway, it seems that an electric car with a fully charged 100kWh battery should be able to do much the same range as a petrol car on a single tank. Glancing at Tesla, they are claiming about 300 mile range for their cars with the biggest batteries. That would suit me fine, as 4 hours is my absolute maximum drive.

[tim...]

it's not that simple though, is it

if you were visiting me for the weekend there is nowhere you could recharge your car when you arrive

so your battery has to be good for the round trip

(FTAOD I live on on of these "modern" estates where nobody has a drive and everyone parks on the road. And I live on the second floor so running a cable out of the window isn't practical either)

tim

[Dave Plowman (News)]

Think you have to be even more careful with the claimed range of an electric car than you do with a maker's petrol MPG figures. ;-)

[Tim+]

Can't argue with that but this is coming from the co-inventor of lithium ion batteries so who knows...

Tim

[Chris Hogg]

Not a problem. Happy to be corrected.

The point I wanted to make was that in order to charge an electric car battery in times comparable with filling the tank with petrol, you'd need an awful lot of amps at an awful lot of volts.

[Dave Plowman (News)]

Plenty live many miles from a filling station too.

[Bill]

In message , Chris Hogg writes

Did anyone else hear the piece on Radio 4 a few days ago about UPS in Birmingham?

Apparently they have converted 6 or 7 of their delivery vehicles to electric power and have been very happy with the results.

But they can't convert any more because 6 or 7 is all they can charge overnight. That uses the total supply available to their industrial site.

[GB]

Tesla claims that you can get a 50% charge in 20 minutes at one of their super-fast chargers. That sounds like around 100kW = 400 amps at 240v, which seems rather high.

[Brian Gaff]

Not while Trump is in charge. Brian

[Chris Hogg]

Yes, I agree with those figures. OK if you want to stop at a service station and pop in for a coffee while you wait, but at busy times there's often a queue for the normal petrol pumps, and they have a fairly rapid turnover, so what it would be like with a twenty minute wait I shudder to think.