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Slideshow: Electric Car Batteries Get Bigger

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Battery weight effect on mileage
briank101   2/13/2012 9:59:03 AM
Just to add the point that weight in an electric car is not as negative a factor compared to non-electrics, due to regenerative braking, in fact if the regenerative braking was 100% efficient (that is if all kinetic energy was recovered back into the battery when braking) there would almost be no penalty with the added weight, plus the added stabily if the batteries can be located low and toward the center of the car, and the fact that cars with higher mass are safer in collisions, with all other things held constant. In the real world with say 75% efficent energy recovery, adding 20% to the cars weight (in batteries) would increase energy comsumption in stop and go (or uphill and downhill) driving by 5% maximum. In constant speed driving the only decrease in efficiency may be due to slight increase in rolling resistance due to the added weight.

The 75% number comes from this article http://www.designnews.com/document.asp?doc_id=235313

rick oleson
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Re: Smaller, not bigger
rick oleson   2/13/2012 10:02:34 AM
It almost sounds like we're relearning how and why the internal combustion became dominant, doesn't it?  It would be nice if you could just carry the amount of energy you need, and/or pick up more along the way in a quick and efficient manner.  Gasoline is not going to carry us in the long term, and battery power (and everything else) brings challenges of its own. 

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Re: Smaller, not bigger
Tcrook   2/13/2012 10:08:04 AM
 A small (10 - 20 HP) ICE w/ generator as a range extender/recharger makes SO much sense.   It's light, allows use of smaller battery, would give unlimited range at in-town speeds, allow recharging while parked when trip is over 50% of battery range and totally eliminates 'range anxiety'.  

BMW useded this in one of their recent prototypes.  I thought it was brilliant.

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Re: Battery weight effect on mileage
Tcrook   2/13/2012 10:14:56 AM
The supercapacitor is a much better answer to capturing energy from braking than a bigger battery.  The 'bigger battering ram is safer' is a loosing proposition when everybody has one.

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90% vs 100%
GlennA   2/13/2012 10:25:00 AM
While it would be nice to have a vehicle to match intermittent needs, could people justify multiple cars ?  My 2009 Aspen Hybrid is excessive for my everyday use - 5.7 Hemi, 6,000 towing capacity, 8 passenger, all-wheel drive.  Even my wife's Prius is excessive for her everyday use - 1.8 (Sterling cycle ?), 4 passenger.  But neither of us could justify having something like the original Honda Insight for everyday - 2 passenger, high mileage - and then a third and fourth car for 'special' days.  And there is always the what-if ;  what if I take the 2-passenger but then need additional passenger or cargo capacity later the same day ? We both accept that our cars are not ideal, but we each are willing to accept the trade-offs of our hybrids.

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Many good points have been made
fredsay   2/13/2012 10:40:22 AM
EV's will really take off when they become "drive-by-wire" where they will get their energy (and driving instructions) from the wires buried in the road (similar in concept to the streetcar or subway trains). Then there won't be any extra weight and there will be unlimited power to draw from. People won't develop anxiety when they need to travel farther than 100 miles.

Until then, it looks like hybrids and ICE will dominate with EV's being just a small percentage. The only other thing which may save EV's will be to standardize the battery packs (dimensions and connectors) so "Filling Stations" can be built where the entire battery pack is swapped out. Imagine gasoline cars if every different brand had their own unique way for delivering gasoline into the tank. Remeber the switch from leaded gas to unleaded? Doubtful that barcoding would have succeeded if every product required different equipment for scanning at the checkout. Or if every different railroad line had their own specs for track design (width). In a more simplified world, VHS vs Beta and DVD's vs (Pioneer) Laser disks didn't break out until the players got together and agreed on standards. Of course they were helped along by the porno industry which became the unifying force.

Until there is similar unified force for battery packs among the different car companies (Porno for battery packs?), EV's will continue to be a niche player. However I could be wrong.

Pass me my "Romancing The Bone" DVD. Turn it up, here comes my favorite part.

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Re: 90% vs 100%
Justajo   2/13/2012 11:00:22 AM
Will we soon see the day when all-electrics must be based on a truck chassis to carry the weight? (Anybody remember the Briggs and Stratton company's electric attempt?) It seems we are fast approaching that point, if we haven't reached it already. This easy fix of "more is better" gives me an uneasy feeling, as it appears to have done with many of the posters here. Shows how far we have yet to go before the EV is ready for prime time with the vast majority of car owners. 

Charles Murray
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Re: Many good points have been made
Charles Murray   2/13/2012 11:06:14 AM
Fredsay: I think you will like the story that we're posting on Wednesday morning. Watch for it.

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Re: Battery weight effect on mileage
BillFZ1   2/13/2012 11:48:16 AM
 "and the fact that cars with higher mass are safer in collisions, with all other things held constant."

Untrue. The reason why heavier vehicles have been safer is not due to the weight of the vehicle but rather the reason for the weight. Many of the specifically heaver cars are SUVs which are often intended for off-road use requireing a stronger chassis/body structure. Many others are Pickups, which lots of people making the engineering comments seem to forget are frequently the bets selling vehicles in North America. The Ford F150 is often the highest selling vehicle of the year. Trucks are built stronger to handle load hauling and also often have better crash surviveability. 

If you put a 400CI V-8 engine in a Toyota Yaris is will be heavier but not better in a crash. The same thing is true of an electric vehicle with a 3/4 ton "gas tank."

Unsubsidized EVs simply don't sell because they don't match up to gas cars, weather we want to admit it or not.

Bill J

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Need to start looking at efficiency
TOP   2/13/2012 12:02:52 PM
When considering EV or any other technology to a) save energy and b) lower carbon emissions efficiency is a key factor. Comparing EV to ICEV is not quite an apples to apples comparison. But there are some factors to look at.

Let's consider gas pump nozzle to flywheel efficiency for ICEV and mains plug to flywheel for EV.

With today's sealed fuel systems evaporative loss of energy is nil. So what goes in the tank  comes out the flywheel minus inefficiencies. If an ICE is 40% efficient then 60% of the energy put into the tank is lost. For an EV there is charging loss (110% put into the battery to get 100% charge) converter efficiency (80-90%) and motor efficiency (90%). So worst case you have 65% of what went into the EV via the plug coming out the flywheel. If you add the efficiency of a plugless charging solution you have 49% coming out the flywheel. And if the EV sits for any amount of time there is self-discharge.

But there is an efficiency to obtaining the electricity at the outlet to charge the EV in the first place. Depending on how the power is generated the efficiency from lump of coal or therm of natural gas to the outlet is going to be 28% to 56% so the overall efficiency from burning hydrocarbons to the flywheel is 14% to 36%.

Admittedly these are all back of the envelope calculations. But the EV doesn't look so good when looking at the whole system. And the EV pollutes even when not running because it's generator, the coal fired plant cannot just shut down at the flip of a switch.

In addition to these considerations EV use will lead to an increased demand for power generation which will lead to smart power systems and Broadband over Power Lines (BPL) which will lead to a new form of pollution of the RF spectrum.

With the current efficiencies of gasoline engines they are still the viable way to reduce greenhouse gases when compared to EVs.

Bigger batteries are necessary because a lot of the curb appeal to EVs (barring the Prius) is high performance with a clean conscience. Charging an 85kWh battery in a reasonable amount of time is no mean feat with today's technology meaning it will be an overnight affair with a purpose wired high amperage connection.

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