It's the Batteries, Stupid!

[hcsharp]

What Michio fails to work out in this over-simplified explanation is the overall power-to-weight ratio for a given distance. For a short distance, batteries win because the motor, transmission and batteries are very light compared to a gas engine, tranny and gas tank.

The problem boils down to the fact that everyone is stuck on the gas paradigm. Going 300 miles between fill-ups is not an advantage of gas, but actually a burden of gas; a consequence of gas stations being so objectionable and inaccessible (compared to your home) that it's necessary to avoid them for 300 miles. Because Michio can't think outside the gas paradigm, it never occurs to him you don't have to go 300 miles, so he concludes that gas wins the power-to-weight-ratio contest due to the long distance. Of course if you shorten the distance, electric wins the power-to-weight ratio battle. And you can only shorten the distance with electric because your re-fueling points are all the places you normally go, like your home.

The only possible exception is long trips, which are rare for pretty much everybody. It's debatable if this is even an exception given how fast an HPC or fast charger is.

To give him credit, it's not easy to think outside the gas paradigm box until you drive it for a week or two.

 

[dpeilow]

You're both right...

 

[JRP3]

What's misleading is the implied suggestion that batteries need similar energy density as gasoline, which leaves out the different efficiencies of the different drive trains. It was just a quick summary of course but it left out an important part of the equation. If we double current Model S pack density we have a 600 mile vehicle, which is more than enough, but we are still no where near the density of gasoline, and we don't need to be.

 

[Futurist]

The problem with gasoline is: Once it is burned - it's gone forever. The battery is ther to store the same amount of energy some thousend times.

 

[TEG]

Discussion of Envia & A123 on an EEstor forum:
TheEEStory.com: Envia Systems: ARPA-E's Greatest Success To Date?

 

[Norbert]

The problem with gasoline is: Once it is burned - it's gone forever. The battery is ther to store the same amount of energy some thousend times.

...the electricity by itself weighs less than gasoline...

 

[Robert.Boston]

Recent posts point to what may be the most important change needed in battery tech: faster recharging rates (without degrading the battery) and/or less range degradation generally.

 

[JRP3]

Maybe, but if the battery is cheap enough cycles become less important. There are already batteries that will probably outlast the vehicle, Altairnano, SCib, but their density isn't great and they are expensive. Tesla's LiCo has higher density and longer cost but doesn't have the cycle life and high C rates. The right blend of cost, density, and life cycles all needs to come together in a single package.

 

[vfx]

I'm a fan of longer range over faster recharge time.

When talking with someone who is unfamilair with driving electric they both seem to carry the same weight in convincing them that an EV will work for them. I'd rather hit them with "It goes 500 miles" than "It charges in 10 minutes" because to make either one happen the batteries need to be improved. Problem with the quick charge is that it requires not only the batteries to improve, but high speed charging stations need to be developed, the there needs to be political will in the form of funding, locations, and support as well as private companies building publicly accessible installations which is expensive.

Give a single choice, I go for longer range.

 

[William13]

+1 vfx

 

[jkirkebo]

I'm a fan of longer range over faster recharge time.

Give a single choice, I go for longer range.

Not me. Given a choice of 300 mile range and no fast charge or 200 mile range and 50kWh CHAdeMO fast charge, I'd definately go for the latter. The former would make long trips impossible for me, the latter would make them easy.

 

[Norbert]

Give a single choice, I go for longer range.

Agreed, however with range needing to be balanced with cost and weight, we'll need fast chargers at least until maybe we have affordable 800 - 1000 mile range batteries, and that's a long time. And given this being the case, a functional fast charging network will not only be truly useful, but also one of the biggest possible perception/game changers which current technology already allows. Plus, most rarely need more than 300 miles.

 

[dsm363]

I'd settle for realistic 300-400 mile range (highway speed at 65-70mph) and 80A level 2 charging at multiple locations.

 

[Norbert]

I'd settle for realistic 300-400 mile range (highway speed at 65-70mph) and 80A level 2 charging at multiple locations.

Why "settle"?

 

[dsm363]

Why "settle"?

I guess I mean that's what I'd consider the minimum for what I would be really happy with for travel. Having a 600 mile realistic range with Supercharging every 100 miles would be even better of course. We'll get there someday hopefully but fast level 2 charging would be great too.

 

[jerry33]

Being able to drive 600-700 miles in a day is a requirement for replacing the primary car, which is what Tesla says you're supposed to be able to do with the Model S. This means if you have an 85 kW pack, you'll need superchargers every 200 miles at a minimum. And if you don't live in California...

 

[dsm363]

I haven't driven 600 miles in a day in over 3 years so it's not a requirement for everyone. For some people it may be though. The larger the range, the less need for frequent Superchargers.

 

[JRP3]

Exactly. Tesla is simply addressing the reality that most people rarely or never take a 600+ mile trip.

 

[jerry33]

Exactly. Tesla is simply addressing the reality that most people rarely or never take a 600+ mile trip.

Maybe in California. Here in Texas 600 miles might not even get you out of the state depending upon which direction you go and where you start from. 600 to 700 miles is a comfortable level for a day's driving (as opposed to 1400+ that some of my co-workers do and that I did when I was younger). I don't know anyone who doesn't drive at least 600 miles when they take a vacation--and that's one way not round trip.

 

[JRP3]

DSM363 lives in Texas :wink: