What Makes the Tesla Roadster Stand Out?

[mheslep]

Do you KNOW the environmental cost to produce those batteries? It's absolutely insane. A Toyota Prius actually does more legitimate damage to the environment through its manufacturing methods than a similarly produced car does through its manufacturing AND entire lifespan of burning gasoline.

Not to mention the gulf oil spill wouldn't have happened if wackjob environmentalists didn't keep coming up with new ways to prohibit drilling in safe waters near shore, forcing companies to move into FIVE THOUSAND FEET deep water.

Nonsense, both paragraphs.

 

[Physics-Learner]

i am a big ev enthusiast. it is probably best that nissan did not put extra money into a thermal management system for their batteries.

at this point, price is the biggest deterrent for the consumer.

the leaf does not have to be the car for everyone. there are many areas in the country where climate is not severe enough (hot or cold) that a thermal management system is needed.

the coda has a thermal management system, although it will only be sold in california for the first year.

but the main gist is that we need to get evs out on the road. the sales force simply needs to be honest about what their cars can and can not do.

so perhaps the leaf should simply not be sold in area with temperature extremes ?

there are many companies coming out with evs, so things will be interesting for quite a few years.

 

[Topher925]

Nonsense, both paragraphs.

You read both paragraphs? I stopped after the first.

i am a big ev enthusiast. it is probably best that nissan did not put extra money into a thermal management system for their batteries.

at this point, price is the biggest deterrent for the consumer.

the leaf does not have to be the car for everyone. there are many areas in the country where climate is not severe enough (hot or cold) that a thermal management system is needed.

the coda has a thermal management system, although it will only be sold in california for the first year.

but the main gist is that we need to get evs out on the road. the sales force simply needs to be honest about what their cars can and can not do.

so perhaps the leaf should simply not be sold in area with temperature extremes ?

there are many companies coming out with evs, so things will be interesting for quite a few years.

Let me start of by saying that every battery with a high volumetric power density will have a thermal management system in one form or another. The Tesla and Volt use a water cooled system (only safe way to go IMO) and the Leaf uses an air cooled system (can be VERY dangerous). Because of this, the Leaf is NOT being sold in the northern states of the US. Its quite a simple strategy really. If you car can't perform in cold weather, don't sell it to people in cold places.

While there are many new electrical vehicles coming out in the next few years (none by GM, Toyota, or Honda BTW) they are all still just a novelty. For things to get "interesting", battery technology needs to advance by leaps and bounds.

 

[Physics-Learner]

gosh, our batteries are already getting us 100 miles. that is plenty for the majority of people.

improvements will be released as they are needed to sell the cars.

if we needed 200 mile battery packs to sell cars today, you can bet your boots that the cars of today would have them.

car companies are just beginning to ramp up production. demand is high, supply is low. waiting lists for what is available, high prices. this will change dramatically as time goes by.

 

[baywax]

Actually, the capacity remains almost the same. What happens is that the kinetics slow down. In other words processes like diffusion and migration limit the discharge rate of the battery so only the apparent capacity really decreases so its really a transport and not necessarily a chemical problem. The effective discharge capacity is decreased by temperature due to decreased conductivity of the electrolyte (creates more overpotential) but its usually diffusion effects that limit the range a battery has in an EV.

I remember an engineer from Ballard (Hydrogen Fuel Cells) telling me about a plate that acts as a membrane between two solutions (not sure if they were sodium and potassium or hydrogen and oxygen or something), he said they were experimenting with gold overlaying a carbon-graphite frame but that the membrane was getting hammered by the amount of activity in the "battery". The whole process, as I remember it, was to glean electricity from the exchange taking place, like osmosis, between the two solutions. This was a process also affected by temperature. However, during the last winter olympics we had about 23 Ballard fuel cell powered buses running up at Whilster which is at about 6000 ft above sea level with the temperature hovering around zero. Perhaps they've overcome the discharge/migration/temp problem.

 

[baywax]

by Topher

PEM fuel cells will operate just find above 0'C although the power output will be decreased. The issue with PEM fuel cells that when water freezes in side of the cell it damages the internal components, most notably the interface between the catalyst electrode layers and the membrane. After a cell has gone through a freeze-thaw cycle a few times these two components will delaminate from each other and cause the cell to operate with reduced performance and can even completely kill it.

Sorry I didn't see this. Thank you.

 

[baywax]

Do you KNOW the environmental cost to produce those batteries? It's absolutely insane. A Toyota Prius actually does more legitimate damage to the environment through its manufacturing methods than a similarly produced car does through its manufacturing AND entire lifespan of burning gasoline.

Not to mention the gulf oil spill wouldn't have happened if wackjob environmentalists didn't keep coming up with new ways to prohibit drilling in safe waters near shore, forcing companies to move into FIVE THOUSAND FEET deep water.

It would be nice to see some references from you, backing up your statements.

 

[mheslep]

the leaf does not have to be the car for everyone. there are many areas in the country where climate is not severe enough (hot or cold) that a thermal management system is needed.

I'm unaware of any place in the US that could do without year round.

 

[russ_watters]

Actually, the capacity remains almost the same. What happens is that the kinetics slow down. In other words processes like diffusion and migration limit the discharge rate of the battery so only the apparent capacity really decreases so its really a transport and not necessarily a chemical problem. The effective discharge capacity is decreased by temperature due to decreased conductivity of the electrolyte (creates more overpotential) but its usually diffusion effects that limit the range a battery has in an EV.

Slides 7 and 8 here imply that the voltage stays constant while the amp-hour capacity drops substantially (15% from 25C to 0C) with temperature for a lithium battery.
http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/evs17poster.pdf

Similar data for lead acid: http://www.engineersedge.com/battery/discharge_rate_temperature_effects_battery.htm

 

[mheslep]

Actually, the capacity remains almost the same.
[...]
The effective discharge capacity is decreased by temperature due to decreased conductivity of the electrolyte (creates more overpotential) but its usually diffusion effects that limit the range a battery has in an EV.

Distinction without a practical difference?

 

[Topher925]

Slides 7 and 8 here imply that the voltage stays constant while the amp-hour capacity drops substantially (15% from 25C to 0C) with temperature for a lithium battery.
http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/evs17poster.pdf

Yes, but that's not telling the whole story. Slide 7, top center graph, shows that as discharge current increases and temperature decreases the affective capacity decreases just as Peukert's Law states. However, the experimental data in this graph shows that at low current densities the affective capacity begins to converge to some value greater than 7Ah.

So of course temperature will always decrease the affective capacity, but my point was that its both temperature and operating conditions that affect the observed capacity, not just temperature alone. For example in an electric car which has high discharge rates the affect of temperature on capacity can be substantial, even if you account for relaxation. But for an application like the Kindle, where the battery is discharge over a period of a month or so, the affects of temperature on capacity can be insignificant.

 

[mheslep]

Well the math (from Russ's NREL slides) says all. The internal resistance of any battery, created mainly by the chemistry kinetics, is R = ΔV/I = f(SOC,T,charge/discharge,cycle*). The energy wasted is approximately I² R, meaning useful capacity decreases with increasing load. For high power Li Ion batteries R is typically very, very low, perhaps 1 milliohm for even a laptop sized battery, when T is greater than ~0 deg C.

*Cycle, or battery age, is my addition.

 

[baywax]

I'm unaware of any place in the US that could do without year round.

Wait, I've seen some of those American bowling alleys... they're huge!

 

[Physics-Learner]

well i guess we need to define what temperature extremes are, then.

i think of california as having lots of areas without extremes.

 

[mheslep]

well i guess we need to define what temperature extremes are, then.

i think of california as having lots of areas without extremes.

"[URL LA Hits All-Time High of 113 Degrees
[/URL]
"At Sacramento International Airport, extremes have ranged from 18 °F (−8 °C) on December 22, 1990 to 115 °F (46 °C) on June 15, 1961"

Redding, Ca July average high: 98.3F

and so on. Not much humidity, which is nice for people and other evaporative cooling systems, useless for batteries.

 

[Physics-Learner]

you picked one day in la. la also had one of the coolest summers on record.

lots of northern california, like san francisco, has cloudy weather all the time.

california has a long coast line, where the majority tend to live.

 

[mheslep]

you picked one day in la.

So? As I said:

I'm unaware of any place in the US that could do without year round.

Cook a discharging EV battery in that kind of heat for a few days without some kind of thermal management and you will likely measurably shorten its (currently expensive) life. Drive up into the Sierras in the Winter without a battery heater and you may find the vehicle range cut in half while there.

 

[Topher925]

you picked one day in la. la also had one of the coolest summers on record.

lots of northern california, like san francisco, has cloudy weather all the time.

california has a long coast line, where the majority tend to live.

Most people won't buy a car if they can't drive it one or two days out of the year. This is a big reason why you see so many SUVs and trucks in the northern part of the states that get a lot of snow.

 

[Physics-Learner]

most of these first purchases are not single-car families. but i don't think a few days in a year is going to deter sales of an ev without a superior tms.