# Cars, cars and electric cars

Discussion in 'Just Talk' started by joinerjohn1, Jul 26, 2017.

1. ### longboatScrewfix Select

'They' could do that, but it would be inefficient so they won't.
The major problem at the moment is the battery technology itself, ie, they are simply too heavy.
When (if) it becomes possible to pack say 50-100kwh of energy into a unit weighing 20-50kg then we could do away with petrol stations and have battery stations instead.
And possibly a spare unit at home or in the boot of the car.

2. ### facilitiesGuest

To a certain extent electric cars are self charging when in use bit like a dynamo or alternator when the car is in motion it partially charges the battery.

About 4 years ago the Hospital Trust I worked for purchased a Nissan Leaf, it's range on a full charge was about 100 miles (think they are better now) if there was no self charging aspect the range would have been reduced to perhaps 70 or 80 miles

3. ### Deleted member 33931Guest

It would be inefficient to the point of being counter-productive.

Hence my sarcy (DAMN!) comment about perp-motion devices.

Any energy captured by the car-mounted wind turbine would be more than offset by the extra air-friction caused by it.

The only way I can see it working is if they used a similar tech to the 'regenerative' (?) braking they have on many electrical cars - they use electrical generators to slow the car, so catching that energy.

Now, if you could have a roof-mounted turbine flip up in to the air every time you applied the brakes, that would do it.

A teeny bit

4. ### btiw2Screwfix Select

Yeah. Let try and avoid the sarcy comment when someone asks an honest question.

Yup. Where there's heat there's wasted energy.

In the case of braking - a LOT of energy.

Take a one tonne car slowing from 70 mph (~30 ms^-2).
That's mv^2= 1000 x 30 x 30 = 900 kJ of energy.[1]

This drill:

is 18V and has 5Ah batteries.
So each battery supplies (roughly)
5 x 60 x 60 x 18 = 324 kJ [1][2]

So stopping on the motorway once wastes enough energy to fully charge nearly three of these batteries.

Capturing the energy is the trick.

[1] My calculations could be wrong. High school physics was a long time ago.
[2] the x 60 x 60 is to turn hours into seconds.

5. ### btiw2Screwfix Select

At least one bit was wrong.

~30 ms^-1 not ~30 ms^-2

Doesn't change the calculation though.

6. ### Harry StottleScrewfix Select

People are attracted to electric cars presently because the fuel cost is so low, but once established the Government will probably whack up the road tax to compensate for the loss of diesel/petrol tax revenue.

Deleted member 11267 likes this.
7. ### Deleted member 11267Guest

I Remember when diesel was roughly half the price of petrol when most cars and vans were petrol.
Now that all vans are diesel and lots of cars also diesel,the revenue as usual rip off the motorist because they could not allow a cheaper fuel, doing more miles per gallon and motorists not filling up so often, therefore the diesel price hike.
As usual it is the motorist who always suffers getting used as a cash cow.

8. ### btiw2Screwfix Select

Errr, yes. If we want health services and pensions then the tax revenue has to come from somewhere.

If you're arguing that fuel tax is particularly unfair, then I agree.
It's a tax that discourages economic activity.
• Fuel tax tends to discourage people from taking jobs (if they have to drive it can make the job unprofitable);
• discourages people from travelling to shops;
• acts as a tax on movement of goods and services.
• Fuel tax is a much larger proportion of the income of the working man than those with high incomes (i.e. is largely regressive).
It's a nasty tax, but if we all don't pay fuel tax then who will pay the taxes?
Companies out of surplus profits?
That's commie PJ talk!

I don't know, by 2040 it's possible that self-driving cars will be available; so will most people even need their own cars?

The government will want a tax something that a) we have no choice but to use, and b) they can claim the tax is "for our own good", and c) doesn't hit company profits.
That'll be more beer tax then.

Jord86 likes this.
9. ### 2shortplanksActive Member

1/2mv^2 so only 1 and a bit batteries. Anyway, I'm keeping my old van and getting a biofuel conversion

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10. ### btiw2Screwfix Select

Of course you're right. Thanks.

Your biofuel conversion, 745.7 watts of power there.

11. ### P J ThompsonActive Member

@btiw,
It's not "commie PJ talk" because the PJ manifesto would require no taxation since currency would not exist.

Get it right man

12. ### btiw2Screwfix Select

No currency? But without money how would I know which people are better than others?

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13. ### P J ThompsonActive Member

That's easy.
DA is the best.
Everyone else is rubbish

14. ### Deleted member 33931Guest

Wow, man! Awesome! Thank you

Ch...just when I thought the whole world was against me, a true hero appears.

Not afraid to say what's in their heart - even tho' it'll mean almost certain derision from certain quarters.

Thank you thank you thank you.

(You're taking the pish, aren't you.)

15. ### P J ThompsonActive Member

Would I?

Love you really

Deleted member 33931 likes this.
16. ### Mr. HandyandyScrewfix Select

Well if you were to take a solid part of the existing car cut through and tube it(so air straight through), add a half-fan(air-flow hits inline paddle of half the circumference), no extra resistance would be met, in relation to a solid part of the car.

17. ### Deleted member 164349Guest

Logic (not science) to me says every car should have some solar panels fitted to catch daylight (any is better than none at all?) and wind driven fan, as is used to ventilate the back of certain vans, even if it captures wind energy when car is parked/stationary and not moving so as to not create any extra drag.

im also thinking there must be some fairly good ideas and plans in place already to even to begin to justify such a bold move of moving away from fuel driven vehicles.

I do wonder how big a HGV lorry battery is going to be. 38 tonne hillstart will take a fair current/power I would have thought.

18. ### SparkielevScrewfix Select

yeah and my van and Shi t load of tools and carp in it

19. ### longboatScrewfix Select

Yes, you could use such a system to generate power, but it would be a tiny amount compared to what the vehicle actually uses, and with the weight of the fan and associated ducting taken into account you'd most likely end up with a loss.

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20. ### longboatScrewfix Select

Very big!
The technology is in its infancy though, when the commercial drive is pushed by mass demand you can guarantee that the efficiency, weight, cost and availability will improve rapidly.

Tesla's flag ship 'model s' produces more power than a modern 16 litre diesel engine as fitted for most 44t gross vehicle weights, the torque is lagging a bit, but hey, this is a saloon car were talking about.
1200nm of torque is a lot, about half that of a modern truck engine, the beauty is tho, that's at any rpm.
Instant torque.

0-60, in 2.7 seconds.

I can't afford one...
...yet!

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