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What's the Ideal EV Battery Size?

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Doug_G

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Design News - Captain Hybrid - What's the Ideal EV Battery Size?

Watching the recent activity in electric vehicles (EVs) and plug-in hybrids, it's easy to wonder if there's a thread of consistency in all this, particularly in the area of batteries.

Take, for example, the forthcoming Prius Plug-in Hybrid. It employs a relatively small (160kg), 5.2kWh lithium-ion battery. The small battery results in an all-electric range of just 13 miles, but the strategy seems to make sense for consumers who mix regular short trips with occasional longer ones. Automotive industry analysts expect Toyota's strategy to hit a sweet spot with consumers, in part because the small battery translates to lower cost and shorter recharge times.

So the trend is toward smaller batteries, right? Wrong. The Prius plug-in isn't necessarily a harbinger of what's to come.
 
Top line Model S will have about 17x the battery capacity, and 23x the all electric range.
Opposite ends of the spectrum. Since Plug-in-Prius will be able to plug in and drive some miles on "pure electricity" does that entitle it to be called an "EV"?
 
I had mixed feelings about the article, myself. It shows Toyota's mindset, which seems to be, "people don't care about driving electric; they just want to improve the fuel efficiency of their gas-powered car". I think they're missing the whole point of electric vehicles (IMHO), which is to minimize gasoline usage as much as possible -- if not eliminate it altogether.
 
Top line Model S will have about 17x the battery capacity, and 23x the all electric range.
Opposite ends of the spectrum. Since Plug-in-Prius will be able to plug in and drive some miles on "pure electricity" does that entitle it to be called an "EV"?

Absolutely not. EV should not be in the name at all. The chrome on the car says "HYBRID", and if they say anything about using electricity, they should also say something about gasoline, or if diesel, or if fuel cell. So it should be gas-electric HYBRID, or fuel cell-electric HYBRID. Or maybe gasoline-hamster hybrids if that's what they use.

Way too much playing around with "EV", done purposely and deliberately to confuse the public and muddy the waters.
Thank you CARB and GM, Ford, Chrysler, and other automakers.

Just like the big deal about "V8" engines, or "Hemi" engines as synonymous with POWER, which doesn't necessarily follow.

By the way, Wiki says that NO company is building a hemi engine these days because of weight (cams on both sides of the combustion chamber) and difficulty to meet air quality regulations, since they burn dirty. Some use two plugs (more complexity), so Dodge/Chrysler uses a weird multi ground sort-of hemi shape and calls it a "hemi" so John 6pack will think, "OOOooohh, POWER!

Whereas a true EVer thinks "Tesla": "OOOOOOOOOOOOoooooooh!!!!! Power!!!!!!" That's the difference.
 
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Some PiP (Plug-in Prius) battery info:
Toyota’s First Production Lithium-Ion Drive Battery
...The 2010 Prius PHV has three lithium-ion battery packs, one main and two additional packs (pack one and pack two) with a combined weight of 330 pounds. Each battery pack contains 96 individual 3.6 V cells wired in series with a nominal voltage of 345.6 V DC...

Prius PHV FAQ
...
Why is Toyota using lithium-ion batteries in the Prius Plug-in Hybrid Vehicle, but not in the 2010 or 2011 Prius?
Lithium-ion batteries have greater energy density than nickel-metal hydride batteries, i.e. more energy can be stored with battery size intact. In order to increase the distances driven under electrical power, Toyota is using lithium-ion batteries in the Prius Plug-in Hybrid Vehicle.
In conventional hybrid vehicles Toyota will continue to use nickel-metal hydride batteries in the near term. The technology has proved its value over twelve years of mass production and is extremely reliable. In the future, given cost reductions, lithium-ion batteries could be considered for conventional hybrids.

  • Ni-MH batteries are appropriate for regular hybrids (cost, quality, reliability).
  • Lithium-Ion batteries: higher capacity and reduced size/weight, but not yet ready for market (cost, reliability)...
 
EV range and cost-effectiveness: Chevy Volt versus Toyota Prius plug-in hybrid - Hybrid Cars and Plug-in Vehicles - Hybridcarblog
...What’s the best EV range to achieve plug-in cost-effectiveness? While most plug-in proponents typically believe the most range possible is the best range, it’s cost-effectiveness that ultimately matters most to mainstream consumers — the key to plug-in success — not range...
...Today, most hardcore plug-in fans mock the EV range of small battery plug-in hybrids such as the upcoming Toyota Prius plug-in hybrid, but a new UK EV study demonstrates that Toyota’s 13 miles of EV range might be far closer to the sweet spot of plug-in cost-effectiveness than critics might want to admit. In the UK, for instance, the average single way commute is just 7 miles...
 
Toyota's Approach To Electrification
...With regard to electric drive vehicle batteries, Toyota believes that smaller is better, both from a total lifecycle assessment (carbon footprint) perspective, as well as a cost perspective. Research has shown that plug-in hybrid vehicles with smaller batteries, charged frequently (every 20 miles or less), and using average U.S. electricity, produce less greenhouse gas emissions than conventional hybrid vehicles.* And as battery size increases, so does the battery cost, resulting in higher overall vehicle cost...
*Shiau,Ching-Shin Norman et. al. 2009. "Impact of battery weight and charging patterns on the economic and environmental benefits of plug-in hybrid vehicles." Energy Policy
...As battery electric and plug-in hybrid vehicles come to market in 2012, success will hinge on their value proposition: meeting or exceeding customer expectations by finding the perfect balance between cost and performance...
 
Toyota engineers recently told me that every mile of all-electric range adds about $500 to the initial cost of its vehicles.

And Tesla chargers $70 per mile on the model S, right?

Commenter missnoitall has many unanswered where he is comparing burning to storing as if they are equal. This comment, "Exactly what other consumer device has 8,000 parts? " I have heard before on the radio. "Tesla has too many batteries so it will fail." I was trying to come up with similar consumer examples that dispute the complexity count assertion.
LEDs in a television was my best.
 
The battery pack is somewhat "self healing". Individual cell failures don't take out the whole pack.
On a TV you might notice a "bad pixel", but Tesla can "soldier on" even with some defective cells in a way you may not even notice.
 
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And Tesla chargers $70 per mile on the model S, right?

Commenter missnoitall has many unanswered where he is comparing burning to storing as if they are equal. This comment, "Exactly what other consumer device has 8,000 parts? " I have heard before on the radio. "Tesla has too many batteries so it will fail." I was trying to come up with similar consumer examples that dispute the complexity count assertion.
LEDs in a television was my best.

Christmas tree lights. One can go out, but the tree remains lit. A string of lights is ridiculously NOT complex.
 
Christmas tree lights. One can go out, but the tree remains lit. A string of lights is ridiculously NOT complex.

Umm, there are different types. If each "bulb" is 120V, yeah. But most lights I have seen these days have strings of low voltage lights where one going out takes out a chain. In some cases it is the whole string, in others they might have dual lines (3 wires along) so that only half go off.

http://www.ciphersbyritter.com/RADELECT/LITES/LITESFAQ.HTM
Why is half my string dark? Mini-lights generally have 2 separate circuits. One circuit can go out leaving the other lit.

How to fix Christmas tree lights in series? - Christmas lights | Ask MetaFilter
...I have a Christmas tree with lots of lights on it. The lights are wired in series and are currently not working. So somewhere on this set of lights one or more lights are not functioning. It is a major pain, swapping bulbs for known good ones or peering into each and every bulb with a torch to see if you can spot whether the filament is still there...

But now, with LED bulbs available, they are so much longer lasting (and lower powered) that one need not worry much about a "burnt out bulb."
 
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Umm, there are different types. If each "bulb" is 120V, yeah. But most lights I have seen these days have strings of low voltage lights where one going out takes out a chain. In some cases it is the whole string, in others they might have dual lines (3 wires along) so that only half go off.
But now, with LED bulbs available, they are so much longer lasting (and lower powered) that one need not worry much about a "burnt out bulb."

I should have been more precise. MY Christmas tree lights. When a single bulb goes out, the rest stay lit.

:)
 
That's really making a huge assumption that we're not past or near-past peak oil.

Yes, and not even mentioning that the operating costs with electricity are already much lower than with gas.

(Even though there may be a certain number of drivers with a commute of usually even less than 13 miles. So that's not saying it would never make sense in individual cases.)