Faster better cheaper..... Lithium ion batteries. 1

[moltenmetal]

Compressed air might be quick to charge, but the efficiency and the storage hazard are both really lousy.

 

[cranky108]

If efficiency is your goal, then why are you looking at batteries for storage of electricty?

Storage hazard? What happens if you break the encasement of a battery? If it's liquid, it will leak. If it is immobalized electrolite, the the life, and efficency suffer.

I'm not for compressed air, but I see no reason to not use it as a compairson.

The issue here is the energy density, and speed of charging. For a non-air breathing propulation (no chemical fuels) Air just seems better than lithium batteries.

 

[jmw]

Energy density? Liquid CO2 cartridges?
Oops!
My bad. CO2 is a poison these days.

JMW

http://www.ViscoAnalyser.com

 

[moltenmetal]

Batteries are WAY more efficient in energy storage/retrieval than air or any other gas compressed to high pressure. You lose most of the work of compression as heat, and there's no use for that heat. And unless you pick up heat from the atmosphere during expansion (i.e a large, heavy and drag-inducing air to air heat exchanger you need to carry along with you), all you get is the PxV energy in the gas- a very small percentage of what you put in to compress it.

Air compressed in enormous quantity to relatively low pressures is a different matter. The efficiency is much better and the storage hazard much lower- but then the energy storage per unit volume is nowhere nearly good enough for transportation uses.

A battery leak or even a battery fire is a manageable risk, no different than a gasoline leak or gasoline fire. Though a compressed air leak is no big problem, a high pressure compressed air tank rupture during a crash is a different matter entirely.

 

[jmw]

Just how big a problem would it be to design easy swap batteries?
If the service is good, shorter range would be feasible with smaller batteries.
The G-Wiz doesn't seem that sophisticated (ignoring for the moment the serious safety issues).

Quite obviously 'elf 'n safety wouldn't contemplate actual people lifting and shifting heavy batteries but if there were the imperative, I'm sure a system could be worked out where you drive up to the battery change station, position the car as directed (as you do in a car wash) enter you credit card and push a button. OK, maybe you would hook up to compressed air to provide some energy to eject the battery pack onto a hydraulic tray which would then take away your battery and supply another, identified by micro chip battery or vehicle identifiers.
It could all be automated.

The new batteries would have a weight advantage for the vehicle and charge time advantages for such service stations, it only requires a suitable modular approach and some form of standardisation.

JMW

http://www.ViscoAnalyser.com

 

[IRstuff]

Tesla has already designed a battery system for this type of situation:

http://www.teslamotors.com/roadster/technology/battery

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[jmw]

And in the light of this thread, their claim:
"Tesla starts with thousands of best-in-class Lithium-ion cells ....."
One hopes they haven't invested too much money in a unique battery type and can easily adopt the new cells.

Can anyone advise, with faster charging and faster discharging potential, how will his affect realisable performance?

JMW

http://www.ViscoAnalyser.com

 

[jmw]

As it happens, Tesla say they recharge in 45 minutes......
for a 300mile range.....

I'd sack the web site designer though.
Next to Home page in the menu is Roadster.
You click and it comes up with a page labelled "The New Roadster".
You click on design studio and it says:

We are now reaching the end of Roadster production for North America.

I'd match the opening to this statement and I'd put the current models page first on the menu. Maybe bury roadster details deep n the website.

It makes you wonder just how many sales there were they didn't continue production and how much you can depend on the other cars.
Maybe this is all about battery manufacture not cars?
I've no doubt they answer it all somewhere but I shouldn't have to search and after that start I'm not inclined to.

JMW

http://www.ViscoAnalyser.com

 

[jmw]

PS Tesla don't say anything about brakes.... with no power assist from an IC engine, how do they deliver decent braking and what happens when you batteries start to go flat?

JMW

http://www.ViscoAnalyser.com

 

[cranky108]

Power assist just adds weight, and anyone who drives an old car knows you really don't need them.

I believe that it is automatic transmissions, and power breakes that create stop and go traffic. Without them people would be more mindful of pacing there speed, and not stop and go. We would all be driving more effecently without them.

Besides an electric vacuum pump can be used to power not only power breakes, but also windshield wipers, cruse control, and air vents and even wipers for your headlights. If you really want them.

You really don't need all that stuff, just a radio, and maybe a GPS.

 

[IRstuff]

"how will his affect realisable performance?"

The acceleration is pretty darn good already, so it's unclear whether one would realistically want to push the sytem any more, particularly without knowing what the stress margins are.

Everything in the Tesla is designed for the battery system they have now, so one needs to know what margins the designers applied to determine whether any improvement can be had at all.



TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[moltenmetal]

Don't know for sure, but assume that any decent EV is going to do a lot of regenerative braking. Mechanical friction brakes will be there but not used much.

 

[cranky108]

Regenerative braking will slow a vehicle, but not stop it. It also may not be used for very heavy braking, depending on the elecrtical systems ability to generate energy from the wheels, and the batteries ability to store it (a rate thing, not capacity).

Some of the range will be lost in bad driving habits, or habits which do not allow the regenerative braking to work to it's fullest extent.

Having said that, I believe the technology is there, but not to the point where it will work for most people. However, there are some people who it will work for, and can afford it (sort of like the Stanley steemer). But for the masses of people it will not be there best car to drive.

 

[moltenmetal]

Dunno cranky, my Prius has 130,000 km on it already and the pads and rotors and rear drum shoes are barely worn. It's pretty easy to learn.

 

[moltenmetal]

http://www.inference.phy.cam.ac.uk/withouthotair/cA/page_261.shtml

Very interesting little analysis done in "Without the Hot Air" on electric vehicles and their potential range.

 

[cranky108]

When will we see electric 4X4 pickup trucks with some cargo capacity?
I would get tired of renting that truck at home depo for my wife's plants.

 

[moltenmetal]

What we need to stop is people who buy the huge pick-up because they tow a trailer a few weekends every summer, but then drive the thing 280 days per year as a commuter vehicle. That's why we're pissing through fossil fuels as fast as we are now. And the only reason for that is that fuels are too cheap- and fuel users don't pay the full cost of their consumption.

 

[cranky108]

Maybe they could buy a smaller car for commuter vehicle, if the cars were priced within reasonable limits. I for one won't buy a smaller car because I don't have $30-40,000 to waste for a car that I can't work on. Then another several hundred to put tag and insurance.

Besides, my 4X4 works well in snow. Those other guys just don't seem to make it into work on snowey days.

 

[jmw]

Well, how about a wireless technology to charge vehicles on the move?
That's what is being tested by Bombardier in Canada.
Of course, it could lead to "charging spots" such as in parking bays, and traffic lights..... or well known bottlenecks..... and in speed bump zones? an excellent incentivised traffic calming system.....

PS by "suitable battery technology" perhaps they may refer to the new fast charge batteries we started this thread with?

JMW

http://www.ViscoAnalyser.com