It's the Batteries, Stupid!

[richkae]

There are 2 common modes of driving:
1) City driving where your max speed is 40-45mph and your average speed is really 25mph due to stops and lights. In this scenario 100 mile range means 3-4 hours of driving. Nobody wants to spend that much time in their car driving around town. Under this scenario the vast majority will not regularly approach the limits of their range and the range limit isn't very meaningful.

2) Highway driving where you cruise at a constant 60 - 70 mph. If you get 100 miles of range at 60 and 70 miles of range at 70, thats an hour and 40 minutes at 60, or about an hour at 70.
Its pretty common to jump on the highway and do 70 for an hour and when most think about range this is what they will think about.

I think the manufacturers are doing themselves a huge disservice unless they tell people up front the highway range at 70mph.

 

[AndrewBissell]

Totally agree.

 

[stopcrazypp]

I find it hard to believe that all the "100 mile" vehicles can really all have the same range, given they have radically different battery sizes (from 16kWh for iMiev to 33-35 kWh for Coda and Mini-e). I appreciate there will be differences in drivetrain efficiency an aerodynamics, but a halving of Wh/mile from worst to best seems unlikely.

My conclusion is that Coda will deliver 100 miles in real driving by "not careful" (I.e. Non hypermiler) drivers; Leaf 70 miles; and iMiev about 50 miles.

I would be careful about estimating the Leaf's range. From some Leaf forums, I have read that the quoted 24kWh is only the usable part; Nissan keeps the full pack size secret. Coda's 34kWh figure is the full size of the pack (although it may be all usable, which I suppose makes that point moot).

As far as I know, as soon as the iMIEV hit US shores and started doing official promotion, they ditched the 100 mile rating they got from the Japanese cycle. The max they quote is 80 miles now and magazine testing say it is 50-80 miles. I don't think it as an official EPA range yet. They haven't unveiled the US spec iMIEV yet, but supposedly it will be a bit bigger (and I think it might have a 20kWh pack instead, like one of the concepts).

 

[AndrewBissell]

I hadn't heard that point about the 24kWh being purely the useable part of the LEAF battery. Have you got any pointers on where to read up on it? Thanks, Andrew

 

[AndrewBissell]

I still want to see side-by-side testing of all these vehicles (and the Tesla Roadster) to get real range (battery Wh/mile vs battery capacity) and efficiency (wall Wh/mile) numbers. Side-by-side means same drive, same driver, same time of day.

 

[TEG]

There are 2 common modes of driving:
1) City driving where your max speed is 40-45mph and your average speed is really 25mph due to stops and lights. In this scenario 100 mile range means 3-4 hours of driving. Nobody wants to spend that much time in their car driving around town. Under this scenario the vast majority will not regularly approach the limits of their range and the range limit isn't very meaningful.

2) Highway driving where you cruise at a constant 60 - 70 mph. If you get 100 miles of range at 60 and 70 miles of range at 70, thats an hour and 40 minutes at 60, or about an hour at 70.
Its pretty common to jump on the highway and do 70 for an hour and when most think about range this is what they will think about.

I know lots of families with two kinds of drivers.

#1: The one who commutes to work on the freeway, and drives 70mph for 30 minutes in the morning, and another 30 minutes at night to get back home.
(Assuming no place to charge at work, that comes close to using the whole pack capacity during the day.)
#2: The one who is doing family errands during the day. Taking different kids to different schools, shopping, etc. That is more of the in-town 25MPH average, *but* the total driving time is more but spread through the day in little 15 minute chunks. They too could use up the whole capacity of a small pack, just a different way.

Around here at least, many families have one job far from home, but the spouse is near the local shopping and schools in town so doesn't do much freeway driving, but ends up doing more miles in the day due to more trips.

Anyways, my point is that either range number (city vs highway) can be important. In a family either driver might have a routine that needs to consider pack capacity.

 

[stopcrazypp]

I hadn't heard that point about the 24kWh being purely the useable part of the LEAF battery. Have you got any pointers on where to read up on it? Thanks, Andrew

http://www.mynissanleaf.com/viewtopic.php?f=9&t=321&start=40

I read it in this thread.

 

[TEG]

http://www.hybridcarblog.com/toyota-doesnt-know-batteries-or-evs/

 

[dpeilow]

Hybrid batteries tease big energy capacity while charging in seconds

 

[TEG]

http://pressroom.toyota.com/pr/tms/tmc-outlines-eco-car-plans-battery-179327.aspx

...
TMC is researching development of next-generation secondary batteries with performance that greatly exceeds that of lithium-ion batteries. Such research is aimed to help bring about the revolutionary advances in battery performance that will be necessary for the broad adoption of electric-motor-propelled eco-cars.
• Solid-state batteries: TMC has successfully reduced what is known as particle resistance and has made progress toward creating full solid-state batteries in a promising compact package.
• Metal-air batteries: TMC has determined the reaction mechanism of lithium-air batteries and has clarified its research policy regarding the batteries as rechargeable secondary batteries.

In January 2010, TMC established a division charged with studying production of next-generation batteries. The division, with a staff of approximately 100 researchers, is accelerating its research.
...

 

[Adm]

Those solid state batteries are mentioned here as well (with picture).

 

[TEG]

http://techon.nikkeibp.co.jp/english/NEWS_EN/20101122/187553/

 

[JRP3]

At first I thought they had a 16V cell, but it's 4 cells in series.

 

[vfx]

Batteries post EVs

http://www.wired.com/autopia/2010/11/ev-batteries-will-have-lives-beyond-the-road/

 

[vfx]

http://planetark.org/enviro-news/item/60500

Cars that run on batteries will begin to be competitive with ones that burn petroleum fuels in about five years, the U.S. energy secretary said at the annual U.N. climate talks.

"It's not like it's 10 years off," Secretary Steven Chu said at a press conference on U.S. clean energy efforts on the sidelines of the climate talks. "It's about five years and it could be sooner. Meanwhile, the batteries we do have today are soon going to get better by a factor of two," said Chu, a Nobel Prize-winning physicist.

 

[TEG]

http://www.leydenenergy.com/

 

[JRP3]

Seem to have some contradicting information:

At 36 months, the calendar life of Leyden's Pouch battery is three times longer than the product life of competitive Li-Poly batteries
High Calendar Life: > 10 Years (Calculated)
High Cycle Life: >500 Cycles (100% DOD)

Not so good on cycle life, and 3 year calendar life won't cut it, but 10 would. Which is it?

 

[TEG]

http://www.greenoptimistic.com/2010/12/22/kurt-kelty-tesla-roadster-battery/

 

[TEG]

http://www.foreignpolicy.com/articles/2011/01/02/electric_company

(Interesting comments.)

 

[JRP3]

(Interesting comments.)

EV enthusiasts, swarm!