Electric cars a step nearer mainstream?

[Andy Champ]

Let me guess - engine problems? Bearings or rings? Caused by the engine never getting properly warm because the thermostat was defective?

Andy

[Jules]

Seconded. If I'm in a hurry I'll just bin anything where I can't see at least some of the new message text on screen. Ditto with emails. Scads of unsnipped reply-to text is just as irritating as top-posting IMHO.

cheers

Jules

[geoff]

In message , Tim Ward writes

Your loss there, then

You top post and, especially in uk.d-i-y, people will tend to ignore you

It's a convention that exists for the reasons explained by others

Top posters can rant and rave all they like, but, eventually, they either conform or go away when nobody bothers to reply to them

[geoff]

In message , Tim Ward writes

you just answered your own point there

[Dave Liquorice]

Nope the engine is fine. Diesels just don't generate vast amounts of waste heat at idle.

[Dave Liquorice]

Aye, having worked through your figures and even making each car take

50kWh and adding a supply connection cost of =A320k for 100 spaces over = 10 years. It still doesn't reach your =A33/day surcharge. Make the connecti= on fee =A3200k and you still don't break it. That is with power at todays prices, I used 10p/unit. Interesting...

I wonder how the suits would react to spending half a million quid powering the carpark though?

[Dave]

You are not kidding :-(

I bought a diesel Rover 45 when they went bust. For a 3 1/5 mile drive to or from our house, I am freezing waiting for the heater to come on for the last 100 yards of the journey in winter.

Dave

[Richard Torrens]

I did not mention technical documents. Answering an email containing technical questions is not at all the same thing!

One beauty of technical questions in an email is that the OP can then be linked to the appropriate section of the www site. We have a huge body of tech into there:

[Richard Torrens]

Agreed. I find that posters who are too lazy to snip excessive quoting rarely say anything worth reading!

[dennis]

Go outside ten mins before you start out, run the engine at idle for ~30 seconds, go back in and finish what you are doing. You will find it heats up quite well.

[Sarah Brown]

Yes it is. My car has regenerative braking.

[The Natural Philosopher]

Cast iron bocks usuaully. Taker a long time to heat.

[Adrian]

"dennis@home" gurgled happily, sounding much like they were saying:

Are you suggesting leaving the car idling for ten minutes? Or idle it for

30secs, then leave it for ten minutes?

[dennis]

I wouldn't leave it for ten minutes, someone might nick it. No, its to allow the heat to spread through the block, oil, etc. makes the heaters work quicker. How quick depends on the car.

[Adrian]

"dennis@home" gurgled happily, sounding much like they were saying:

Idling for 30sec will barely put any heat in the coolant, let alone the oil. Standing for ten minutes will certainly loose even that little heat.

Starting from cold, idling for 30sec, then switching off can also cause some petrol engined cars to kick the engine management into a "flood protection" mode which will prevent the car from starting again for an extended period of time.

[Mastuna]

Your comparison is flawed.

First of all, the overall thermodynamic efficiency of an electric car is about 70-80% (discharge losses + electric motor losses). The thermodynamic efficiency of an internal combustion engine is 20-25% at best.

So in an electric car, you only need to store about 1/3 of the energy to drive the same distance.

Secondly, electric cars with in-wheel motors are considerably lighter than ICE cars before adding the battery. Electric motors have a higher power density then internal combustion engines so they are lighter. Furthermore, an electric car can do away with the entire drivetrain (since the motors are inside the wheels), the transmission, the exhaust system and the cooling system, saving even more weight. All this freed up weight and space can be taken up by batteries.

Typical electric cars have 300-500 kg of batteries, even if they don't weigh more than ICE cars overall. Compare that to only 30-50 kg of fuel stored in a tank.

Thirdly, electric cars have regenerative braking and don't suffer from idling losses in city traffic, making them more efficient still. Modern electric motors also operate close to maximum efficiency at all speeds, while ICEs don't.

The overall result is that it is now possible to build electric cars with a range of 500 km, which comes close to ICE cars, even if the energy density of batteries, on a energy/weight basis, is so much lower than petrol.

Range is not what's holding back battery-electric cars anymore. What's holding them back now is the cost and limited lifetime of Li-ion batteries.

[dennis]

It works for me, like I said it varies with the car.

Not any car I have ever used it wont. They must have pretty poor management if they can flood the cat with enough unburnt fuel to need to prevent the engine starting until its evaporated. Which cars are that bad so I can avoid them?

[Adrian]

Mastuna gurgled happily, sounding much like they were saying:

But heavier after.

But the batteries are considerably heavier than the fuel tank.

which plays havoc with the unsprung weight, giving considerably worse ride and handling, and requiring heavier duty suspension.

...and then some...

If they have 300-500kg of batteries, before including the weight of the motors and cabling, then they will inevitably weigh more than an equivalent ICE cars, because an entire ICE drivetrain weighs less than that.

Stop-Start in city traffic is hardly unusual in ICE cars.

Indeed. And the chemistry of those batteries, in manufacture and disposal, is sooooo environmentally friendly.

[Dave Liquorice]

In English 310 miles, the full to "running on air" range of my car is just over 600 miles. I normally fill up somewhere between 450 and 500 miles.

[Mastuna]

It depends on the car.

But even in the worst case scenario, if the battery car ends up 300 kg heavier than the ICE car (that's 20%), it still consumes less energy than the ICE car because its thermodynamic efficiency is so much higher.

Even if the electricity used to charge a battery car were 100% derived from oil power plants, it would still use less oil per km than an equivalent ICE car. Modern combined-cycle thermal power plants are 60% efficient. Electricity transmission is 95% efficient. Charging/ uncharging about 80% and the electric motor about 95%. And don't forget that reforming crude oil into petrol takes a lot of energy too, while power plants are able to burn the heavier oil fractions directly.

That's a good point. Do you know how much an in-wheel motor wheel on the Mitsubishi Colt weighs compared to a normal wheel? Would be an interesting figure to obtain. Each motor is rated at 20 kW. I guess that's why Mitsubishi only put them on the rear wheels where the handling is less affected.

I am not sure how much of a difference unsprung weight really makes. I have driven the same car, an Audi A3, with alloy wheels and steel wheels and I haven't noticed any difference whatsoever. Made me think that perhaps alloy wheels are just a marketing scam. Or maybe I didn't drive it fast enough ;-)

They don't just replace the drivetrain. They replace most of the engine assembly, the exhaust system, and the water cooling system.

True, hybrids do negate that advantage.

That's a difficult comparison to make, because both ICE cars and battery cars are recycled very efficiently these days. Batteries contain valuable metals, so it is unlikely that they will simply be thrown away at the end of their life cycle. Not unlike catalytic coverters. Are the toxic emissions (dicounting CO2) from manufacturing

500 kg of Li-ion batteries worse than the emissions from burning 10,000 L of petrol in an ICE? Hard to tell.

Anyhow, I think that the main advantages of battery cars will be economic, not environmental, once batteries are mass produced at high volume and low price. If the current downward trend in battery prices continues, they may well replace the ICE.