# State of the Art; where are we?



## dougingraham (Jul 26, 2011)

What do you mean by equal?

My conversion is going to be only a few pounds heavier than the original car. If everything works out the way I expect it to then it will have a 70%DOD range of 60 miles. It should be able to do 0-60 several seconds faster than the original. That to me is more than equal.

If by equal you mean similar energy delivered to the wheels per unit of weight then we aren't quite there yet. But I don't see that as any reason to wait. The best batteries we have coming up are in the 250wh/kg range which are approximately 2.5 times higher wh/kg than todays LiFePo4 cells. I believe that will push the people with range anxiety into finding some other reason not to want an electric car.

I personally think we are already more than equal in the areas that matter.


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## Ziggythewiz (May 16, 2010)

When 6 lbs of batteries will let you drive 30 miles, we'll be 'there'. Don't hold your breath, I don't know if that's even theoretically possible, but it doesn't need to be.

All that really matters is the use cases. It's already solved (though expensive) for most Americans; for the weirdos that like to drive 200 miles a day it'll take some time to be practical.


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## PhantomPholly (Aug 20, 2008)

Ziggythewiz said:


> When 6 lbs of batteries will let you drive 30 miles, we'll be 'there'. Don't hold your breath, I don't know if that's even theoretically possible, but it doesn't need to be.
> 
> All that really matters is the use cases. It's already solved (though expensive) for most Americans; for the weirdos that like to drive 200 miles a day it'll take some time to be practical.


This is more in line with the answer I was looking for.

How many pounds of current-tech batteries does it take to drive 30 miles in a 30mpg car?

The use-case nearest and dearest to my heart is electric flight, in which parity or near-parity is an absolute necessity to achieve same-range capability. You do get a small advantage in airplanes because you can eliminate cooling ducts, which add significant drag, and thus go the same distance at the same speed on less power. Too, electric motors tend to be quite a bit lighter when considering fully installed weight (no starter; no oil cooler; etc.). So, if you could drive that 30mpg car 30 miles with, say, 7 pounds of batteries, you could convert an airplane and have similar performance (range, speed, and payload).

Last time I calculated it was several years ago, and I think it took nearly 10x the weight to get the job done. I'm just trying to figure out how close we are.


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## Ziggythewiz (May 16, 2010)

Sounds like we were in a better place several years ago...or maybe your memory is foggy 

1 100AH TS cell is 7.72 lbs, and provides about 320 whs, so if we figure 250 wh/m for a 30 mpg car, it would take around 23 of these cells to get a 30 mile range, so maybe 200 lbs including connections. That's certainly an improvement over the 900 lbs of lead it would require, but still off from gas parity by 30x.

Even all the new tech promising 10x better storage we've heard over the last year will not do it, so I hope you don't mind waiting another 100 years.


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## Tesseract (Sep 27, 2008)

PhantomPholly said:


> ...
> I know that EVs use as much as 90% of the stored energy and gas only delivers around 40% of it's energy in lab conditions, not real conditions, so if you are nice enough to include assumptions about theoretical comparison factors (e.g. "gasoline only delivers 30% in the real world; EV delivers 90% but batteries can only be run 80% dead; etc. so that we can get a pounds-to-pounds comparison) it would make it more comprehensible....


There's one bad assumption in there - the *theoretical* (Carnot) efficiency of an internal combustion engine is 37% at 25C using ordinary materials. If you were to build the engine out of refractory metals like Inconel, Titanium, etc., then you *might* be able to push that a few more points higher.

The typical internal combustion engine in a car gets a best case efficiency of around 18%, or half the theoretical ideal.

Skipping over lots of math, the 33kWh of energy in a gallon of gas is equal to about 7.1kWh of battery pack (100% DoD). Divide by whatever fraction of DoD you want to use to get the needed real world battery pack capacity; e.g. - 8.9kWh if DoD is limited to 80%.

1 gal. of gas weighs 6.lbs (2.76kg)... and takes up 3785cc. 7-9kWh of battery pack weighs... umm... well, let's see. A Winston (neè Thundersky) 200Ah cell takes up 5115cc and weighs 7.3kg but only stores ~0.64kWh, so you'd need 11-14 of those to equal one gallon of gas.

All of this was obtained via Wikipedia with the exception of the Winston cell data, btw...


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## Yukon_Shane (Jul 15, 2010)

This is a really interesting question and discussion. 

For me the real question of parity with internal combustion engines is more a question of cost then kg.

If someone developed a battery technology tomorrow that had the same energy density as gasoline but cost $1,000/Watthour it would be interesting to talk about but it wouldn't really change the world at all. If, on the other hand, our existing LiFePO4 technology reached a production efficiency and economy of scale such that the price came down to $0.10/aH then I think the world would be a very different place. At that price the engineers would have a strong impetus to solve any issues associated with energy density.


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## PhantomPholly (Aug 20, 2008)

Tesseract said:


> There's one bad assumption in there - the *theoretical* (Carnot) efficiency of an internal combustion engine is 37% at 25C using ordinary materials. If you were to build the engine out of refractory metals like Inconel, Titanium, etc., then you *might* be able to push that a few more points higher.
> 
> The typical internal combustion engine in a car gets a best case efficiency of around 18%, or half the theoretical ideal.
> 
> ...


Ok, so to distill all that down:

8kWh of battery =~ (approx) 1 gallon of gas for propulsive purposes.
That's approximately 12 LiIon batteries in 2011 (I'll be optimistic), each weighing about 7.3Kg.
12 batteries * 7.3Kg = 87.6Kg = 192lbs of batteries = 1 gallon of gas
192 lbs / 6lbs = 32 times the weight of a gallon of gas.
Is that math correct? Gawd, no wonder we're not all driving EVs... 

By this formula, it would take 7,800 lbs of batteries to replace 42 gallons (252 lbs) of gas in my 1,500 lb airplane...


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## Ziggythewiz (May 16, 2010)

You've got it. Better get a super guppy


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## Sunking (Aug 10, 2009)

Tesseract said:


> Skipping over lots of math, the 33kWh of energy in a gallon of gas is equal to about 7.1kWh of battery pack (100% DoD). Divide by whatever fraction of DoD you want to use to get the needed real world battery pack capacity; e.g. - 8.9kWh if DoD is limited to 80%.


First let me say I am a huge supporter of EV's. I am convinced it is the answer to lightweight vehicle ground transportation.

But if you are going to say the 33Kwh in a gallon of gasoline is = to 7.1 Kwh of electricity is ignoring some very important inputs. mainly where did that electricity come from and how it was generated. Being an EE for 30 years with 15 of that in electric utility generation and transmission th every best generation stations are only about 35% efficient in converting the heat in the fuel (coal or NG) to electricity, then minus the 10 to 15% loss in transporting it from the plant to you home, and another 20 to 50% loss converting it to DC and storing it in a battery.

Once you take all the inputs it all comes out about the same. Basically instead of the energy coming from petroleum you have just shifted it to Coal, NG, or Uranium.


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## lowcrawler (Jun 27, 2011)

Sunking said:


> Once you take all the inputs it all comes out about the same.


If you are going to do all that accounting for electricity, you need to do the same for petrol -- that is, a full well-to-wheel calc. (which, once done, re-tips the scales to electric)



> Basically instead of the energy coming from petroleum you have just shifted it to Coal, NG, or Uranium.


... or solar, tidal, geothermal, wind, etc...


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## Sunking (Aug 10, 2009)

lowcrawler said:


> ... or solar, tidal, geothermal, wind, etc...


None of which can never replace any of the fossil fuels or nuclear generated electricity. .


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## lowcrawler (Jun 27, 2011)

Just because no single tech can currently replace fossil fuels doesn't mean the alternatives aren't viable or worthy of pursuit.

Not to mention the 'all considered' conclusion you make is faulty...


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## zeroexcelcior (Aug 2, 2011)

Yukon_Shane said:


> If, on the other hand, our existing LiFePO4 technology reached a production efficiency and economy of scale such that the price came down to $0.10/aH then I think the world would be a very different place. At that price the engineers would have a strong impetus to solve any issues associated with energy density.


Very well said, I agree completely. Just from this forum alone, there is no doubt that electric vehicles are practical and viable. I think that the upfront cost of batteries is currently the biggest roadblock. While certainly a reduction by an order of magnitude would be fantastic, even a reduction by half would cause an explosive increase in EV adoption.


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## Ziggythewiz (May 16, 2010)

Sunking said:


> But if you are going to say the 33Kwh in a gallon of gasoline is = to 7.1 Kwh of electricity is ignoring some very important inputs. mainly where did that electricity come from and how it was generated. Being an EE for 30 years with 15 of that in electric utility generation and transmission th every best generation stations are only about 35% efficient in converting the heat in the fuel (coal or NG) to electricity, then minus the 10 to 15% loss in transporting it from the plant to you home, and another 20 to 50% loss converting it to DC and storing it in a battery.
> 
> Once you take all the inputs it all comes out about the same. Basically instead of the energy coming from petroleum you have just shifted it to Coal, NG, or Uranium.


No one is talking about how the energy gets into the car. We're only discussing the weight of gas vs batteries that it takes to go a mile (or 30). Pretty simple, no need to complicate things with wheel to well calculations...


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## aeroscott (Jan 5, 2008)

I'm thinking 300-400 w/kg will give a modest 150-200 mile range airplane . Some of the engine weight saving , cooling drag reduction etc. Will lesson the need for better batteries . Many pilots just like to get in the air for that little blast of freedom. IE , short ride much less battery intensive say 50 mile range.


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## Duncan (Dec 8, 2008)

_Ok, so to distill all that down:_

_8kWh of battery =~ (approx) 1 gallon of gas for propulsive purposes._
_That's approximately 12 LiIon batteries in 2011 (I'll be optimistic), each weighing about 7.3Kg._
_12 batteries * 7.3Kg = 87.6Kg = 192lbs of batteries = 1 gallon of gas_
_192 lbs / 6lbs = 32 times the weight of a gallon of gas._
_Is that math correct? Gawd, no wonder we're not all driving EVs... 

By this formula, it would take 7,800 lbs of batteries to replace 42 gallons (252 lbs) of gas in my 1,500 lb airplane... _ _

_For your airplane - yesfor a car you lose ~ 300 lbs of associated junk when converting to electric - that is the equivalent of 12Kwhrs before you get started_, _the petrol tank and fuel give another 100 lbs (4Kwhrs)So you have 16 Kwhrs with no compromisesat all_ - 64 miles

_Then you can start losing fat and replacing it with batteries_ - 

_So 150 miles is about par with present batteries,


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## Tesseract (Sep 27, 2008)

Sunking said:


> ...But if you are going to say the 33Kwh in a gallon of gasoline is = to 7.1 Kwh of electricity is ignoring some very important inputs....


Of course it's ignoring some important inputs, but they are the kind of details that the end user won't know, whether absolutely speaking (ie - impossible to know) or, at the very least, practically speaking (ie - too much work to find out, but otherwise knowable). For example, who here can tell me at any given moment in time what percentage of their electricity is coming from coal, nuclear, natural gas, hydro, etc? I certainly can't tell you that data, even though I know that there are coal and nuclear base load plants along with natural gas peakers in my area.

At any rate, the questions, "how many batteries are needed to equal the same volume/weight/price of gas?" are answerable whereas your complicating conditions are not, so they are irrelevant _ab inito_.


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## Jan (Oct 5, 2009)

Tesseract said:


> For example, who here can tell me at any given moment in time what percentage of their electricity is coming from coal, nuclear, natural gas, hydro, etc?


To make it even more complex, and more off topic: The electricity consumption at night is lower than most power plants can modulate to. Much lower, that's one of the reasons that night tarifs are so much cheaper. If this period of the day is going to be used for charging, the first users will only improve the efficiency of the power plants, at no cost. No extra oil, coal or whatever shall be burned. Until the change in power type demand forces us to build new power plants. Oh, and another thing: eventualy power plants will transmit data through their lines (what already hapens), telling chargers to start, stop or throttle back, if the user wants the lowest tarif, so the plant can run at its most efficienst point.


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## Tesseract (Sep 27, 2008)

Jan said:


> To make it even more complex, and more off topic: The electricity consumption at night is lower than most power plants can modulate to....


Good point!

The comparison of ICE vs. EV just gets murkier and murkier the farther you try to take it beyond the two drivetrains.


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## PhantomPholly (Aug 20, 2008)

aeroscott said:


> I'm thinking 300-400 w/kg will give a modest 150-200 mile range airplane . Some of the engine weight saving , cooling drag reduction etc. Will lesson the need for better batteries . Many pilots just like to get in the air for that little blast of freedom. IE , short ride much less battery intensive say 50 mile range.


Yep, good for trainers and weekend sight-seers.

Useless for travel.


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## PhantomPholly (Aug 20, 2008)

Tesseract said:


> Good point!
> 
> The comparison of ICE vs. EV just gets murkier and murkier the farther you try to take it beyond the two drivetrains.


Too true. For example, if everyone switched to an EV and ALL of that power came from coal, we would still reduce "automobile emissions" by about 50% because power plants are so much more efficient at extracting power from the available heat produced than ICE.


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## aeroscott (Jan 5, 2008)

except if we had fast charge , We could stop every hour for a 15 minute fast charge.


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## Ziggythewiz (May 16, 2010)

Fast chargers would be awesome for airplanes. Intead of using a C-130 tanker, you'd just fly over a tesla coil that zaps your batteries full.

We just need batteries that can handle the 1,000,000 C charge rate...


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## Roy Von Rogers (Mar 21, 2009)

The batteries are not the roadblock, its how to supply a high amount of current to them. Winston and Calb cells can take 3C charge, so a 100ah cell can be charged at 300 amps.

The average home supply in the US is 200 amps, how much of that could you dedicate to charging ???


You will need a three phase supply to charge such batteries at such a charge rate.

Roy


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## PhantomPholly (Aug 20, 2008)

aeroscott said:


> except if we had fast charge , We could stop every hour for a 15 minute fast charge.


100 mile range; 210 mph airplane. You spend 15 minutes climbing to altitude, 15 minutes in cruise, and 15 minutes in high speed descent / approach / landing and arrive with empty battery. You spend another 15 minutes taxiing to-from the runway. If they have your theoretical fast charger, you spend 20 minutes recharging (5 for hookup / payment / unhook, 15 actually charging). You've now spent 1 hr 20 minutes travelling 100 miles, for an average speed of 75mph - and that's only if quick chargers are conveniently located at airports 100 miles apart directly along your route of flight.

You might as well drive; it's useless for traveling.


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## PhantomPholly (Aug 20, 2008)

Ziggythewiz said:


> Fast chargers would be awesome for airplanes. Intead of using a C-130 tanker, you'd just fly over a tesla coil that zaps your batteries full.
> 
> We just need batteries that can handle the 1,000,000 C charge rate...


I seem to remember that super-intense magnetic fields (of the sort that would be necessary to provide your hypothetical quick-charge through induction) can actually rip your brain's neurons apart through interaction with the iron in your cells.

I'll pass, thanks!


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## Duncan (Dec 8, 2008)

To recharge on the "fly" you need a ground station with a "MASER" (laser using microwaves - invented BEFORE the laser) and rectennas (antennas) built into your wings,

Your ground crew point the maser at you as you fly over at numpteen thousand feet and re-charge your batteries as you fly past


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## dougingraham (Jul 26, 2011)

Roy Von Rogers said:


> The batteries are not the roadblock, its how to supply a high amount of current to them. Winston and Calb cells can take 3C charge, so a 100ah cell can be charged at 300 amps.
> 
> The average home supply in the US is 200 amps, how much of that could you dedicate to charging ???
> 
> ...


A residential service in the US is typically 240V at 200A. At night when you aren't using the electric oven, clothes dryer, water heater you could use probably 170A of it safely. This means 40.8kw. At 90% efficiency this drops to 36.7kw and you ought to be able to do better than 90%. So you can charge your 20kwh pack to 80% in 26 minutes. The rest of it will take the next 45 minutes if you really want to top it off. But that assumes the battery was exhausted when you started. If you assume that you only go the average 30 miles per day at a utilization of 200wh/mile then to replenish the 6wkh used will take under 10 minutes. Of course all this assumes a charger that can do 36kw and it would be big enough I wouldn't want to carry it in the car. 36kw would be 250A at 144v which is essentially a level 3 charger.

A 208 three phase service isn't necessary to do home charging at night for the typical person. Even if you have 3 average drivers each with their own car you can charge easily at night. You can't run them all at the same time but there is plenty of time.

With a 90% efficiency on the charger there would be about 4100 watts of waste heat. You could dump that into your water heater or dry your clothes with it. In the winter you could use it to heat the house or the car. The one that makes the most sense is heating water because you can store it for later use. Take a 10 minute shower while the car charges.


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## PhantomPholly (Aug 20, 2008)

Duncan said:


> To recharge on the "fly" you need a ground station with a "MASER" (laser using microwaves - invented BEFORE the laser) and rectennas (antennas) built into your wings,
> 
> Your ground crew point the maser at you as you fly over at numpteen thousand feet and re-charge your batteries as you fly past


Microwaves - heat - ouch....


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## madderscience (Jun 28, 2008)

Something else nobody brought up about the relative weight of batteries vs. gas:

Say the relative energy storage density of gas to some arbitrary battery chemistry is 20:1 (roughly gas vs. lithium I believe) and the overall efficiency improvement of electric to gas is 4:1 then

So if 1 gallon of gas takes you 30 miles and so does 150lb of said batteries.

HOWEVER it takes 100 gallons of gas to go 3000 miles, but it still takes just 150lbs of those batteries. In fact, if the battery has a 1000 cycle lifespan, you really can get 30,000 miles out of them, or what would have taken 1000 gallons of gas.


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## PhantomPholly (Aug 20, 2008)

madderscience said:


> Something else nobody brought up about the relative weight of batteries vs. gas:
> 
> Say the relative energy storage density of gas to some arbitrary battery chemistry is 20:1 (roughly gas vs. lithium I believe) and the overall efficiency improvement of electric to gas is 4:1 then
> 
> ...


The fact that batteries are not fuel, per se, has certainly been discussed - at the end of the day it is more or less irrelevant to the user. 

In the example you give, you would have to "re-fuel" at least 100 times to go 3,000 miles. As I pointed out in my airplane example a few posts earlier, this has a tremendous adverse impact on your average rate of travel (not to mention how tired you will be at the end of a cross-country trip).

Another factor for airplanes has to do with your point, however. Many, perhaps most airplanes allow a higher takeoff weight than max landing weight. This is no problem when you burn off fuel in flight, but will be an additional limitation when converting aircraft to battery power - you will always be "landing heavy."


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## Ziggythewiz (May 16, 2010)

Good point. All electric planes will be limited to the safe landing weight from the get-go...EXCEPT for military planes which have a cargo to dump en route (bombs, supplies, etc). These would also be an ideal place to test/develop such technologies as they have infinite $$$\terrorists to burn anyway.


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## IamIan (Mar 29, 2009)

Just my 2 bits:

( Generalizations of course )

( Of course Gasoline is not a uniform mixture ... varying ~4% energy content is normal ... and of course E10 and other mixes have even less energy content ... which only serves to further narrow the gap... E10 is closer to being equal to batteries than E0 is , just due to energy content difference. )

There are many ways to do the comparison ... 


Energy: ( kwh/kg , kwh/L , kwh/$ )
Power: ( kw/kg , kw/L , kw/$ )
Pollution
etc.


From my perspective by energy is more meaningful ... more specifically the amount of energy to perform the work we want to do ... wasted energy for other things is just wasted, and might as well not even be there in the first place.

The massive difference in operating efficiency between a BEV and a ICE ... from Plug/Pump to the wheels ... effectively means that the fuel you pay for in the ICE effectively has less than 1/2 the energy content that is actually does chemically.

So if we wanted to error on the side of being friendly to gasoline / the ICE... we use *THESE* numbers at the 1/2 energy value ... although some people I've talked to have argued in favor of 1/3 energy value *THESE* numbers.

Energy per Mass ... kwh/kg
1 kg of Gasoline might have ~13 kwh of chemical energy ... It is worth less than *~6.5 kwh/kg* *~4.3 kwh/kg* for a BEV... that is about *~30x* *~20x* more energy content per kg than what I've seen from today's commercially available batteries.

Energy per Volume ... kwh / L
1 gallon of gasoline might have ~36kwh of chemical energy ... or ~9.5kwh/L ... but is worth less than *~4.75kwh/L* *~3.16kwh/L* for a BEV ... which is about *~30x* *~20x* more energy per unit volume than what I've seen from today's commercially available batteries.

Energy per $ ... kwh / $
At ~$3.00 per Gallon ... you are getting ~12kwh/$ ... but is only worth about *~6kwh/$* *~4kwh/$* ... which is equal to paying *~$0.167/kwh* *~$0.25/kwh* from the utility ... for a rough estimate divide the price $ per Gallon , by about *~18* *~12* to get the rough equivalent cost per useful kwh of electricity ... which varies greatly ... some places electricity is cheaper than that today ... some places it is more expensive than that today.

How many kwh of energy at the wheels , it takes to move two otherwise equal vehicles is the same.

As a further generalization ... I'd go in the middle and say modern state of the art for BEV requires the batteries to use about ~25x more weight and volume to go the same distance as it would take to go that same distance from gasoline.


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## drgrieve (Apr 14, 2011)

Although highly variable for each car and build you do before adding batteries how much extra weight have you extracted on average as a multiple of the fuel load?

What I'm getting at is that with the weight savings you could have 2 or 3 times the fuel equivialent weight on board.

So that would bring the figure down to 10x to 15x.

Perhaps another way of calculating is determining how much weight you have to go back to stock weight (with all liquids) and then determing the kWh/kg need to drive a range of 600kms (370 miles).

For efficient folks at 80% DOD this is around a 100 kWh pack.

If you could get a 100 kWh pack to weigh 100 kgs you'd be close to stock weight. So thats 1kWh per kg or roughly 10x on todays LiFeP04 but only 4x the energy density of Panasonics batteries scheduled for 2013.

So I think we are getting much closer than 30x would suggest.


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## Dennis (Feb 25, 2008)

Back in the 1950's a nuclear powered turbine jet engine were designed that used the heat from the nuclear reaction to heat up the air to such an extent that it was like those burners inside petrol powered turbine jet engines that made the turbine blades turn. It did work, but they where bulky and shielding was an issue.

Today though, I think it could be made safe and have it drive a 400 Hertz alternator with their built in rectifiers for a DC output to feed power to DC motor controllers or AC motor controllers. It would be lightweight and the energy density of the the radioactive material is many orders of magnitude greater than petroleum based fuels and it would last many years before needing refueling. Of course the public would not like this and politicians who like to win votes would be sure to strike this down even if it was shown to be safe in an unrealistic wreck that did not cause a breach in the radioactive containment area..... So we are stuck with batteries..


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## Jan (Oct 5, 2009)

Dennis said:


> Back in the 1950's a nuclear powered....


Talking about nukes: Nuclear waste emits alpha and beta particals, alpha is positive and very easy to catch, beta is negative with a much higher penetration grade, but als not to hard to catch. So if you make a layers of nuclear waste, a alpha absorbing layer, an beta absorbing layer and so on, you've got a versy simple nuclear battery made out of waste. I've no idea how much energy or power it would produce. And you've got still the same problem to contain the gamma rays. Would be an interesting experiment with now just lying around nuclear waste.


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## rochesterricer (Jan 5, 2011)

Sounds like you might be describing something like this:

http://en.wikipedia.org/wiki/Atomic_battery


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## RE Farmer (Aug 8, 2009)

Pholly, 

In regard to your original question regarding the state of the art, have you seen the Green Flight Challenge results showing that the 1st & 2nd place winners were EVs that got twice that eMPG/seat AND posted ~30% speed advantage over the ICE planes. See the following for the results:

http://www.eaa.org/news/2011/2011-10-13_cafe.asp

Further, Panasonic (cell supplier to Telsa) is coming out (2012-2013) with a Si-anode cell in the 18630 format that is ~260Wh/kg vice the ~100Wh/kg of CALB/TS cells. These cells would give your 100 mile, CALB powered car a Tesla-like range of 260 mi. for the same pack weight - provided you want to spot-weld many 1000's of these cells into modules.

http://en.akihabaranews.com/36777/p...-li-ion-batteries-to-offer-30-higher-capacity


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## PhantomPholly (Aug 20, 2008)

RE Farmer said:


> Pholly,
> 
> In regard to your original question regarding the state of the art, have you seen the Green Flight Challenge results showing that the 1st & 2nd place winners were EVs that got twice that eMPG/seat AND posted ~30% speed advantage over the ICE planes. See the following for the results:
> 
> ...


Yes, quite impressive. Let's see, neither traveled more than 200 miles. Speed was right at 100mph. Energy used was 35-65KwH. Let's say 64KwHrs @ 200lbs / 8 KwHrs = 1600 lbs of batteries. I'd say these planes were purpose-tailored for these competitions, and not likely to be any competition to a Skymaster any time soon.

As for the Silicon anodes, previous articles stated that this technology results in lowered number of useful charge cycles using current technology. Now if they combine that chemistry with some newer techniques, that boost might not come with a sacrifice of cycles.


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## RE Farmer (Aug 8, 2009)

PhantomPholly said:


> Yes, quite impressive. Let's see, neither traveled more than 200 miles. Speed was right at 100mph. Energy used was 35-65KwH. Let's say 64KwHrs @ 200lbs / 8 KwHrs = 1600 lbs of batteries. I'd say these planes were purpose-tailored for these competitions, and not likely to be any competition to a Skymaster any time soon.


I wasn't trying implying that they were ready for prime time as these craft were purpose built for the CAFE competition. But, 2 hr duration for a 4-place craft is impressive, and even more so was the fact that they beat the snot out of the dino-powered craft. Essentially, I was trying to address your question on the state-of-the-art of EV vs. ICE-powered vehicles.



PhantomPholly said:


> As for the Silicon anodes, previous articles stated that this technology results in lowered number of useful charge cycles using current technology. Now if they combine that chemistry with some newer techniques, that boost might not come with a sacrifice of cycles.


While I don't have first hand data, my understanding is these cells drop to 70% capacity @ ~300 cycles then remain around that capacity for another couple thousand cycles. Mostly, I wanted to show that energy densities are improving. I forecast (possibly on a previous thread you started) that EV range capabilities will double, or better, every 2 yrs. 

I concur with the 30X current difference between ICE and EV effective energy densities. Assuming the 30X difference and my doubling forecast, we would have parity in ~8-10 yrs. (2^5 = 32X; 5*2 = 10yrs). My MG would almost be there if I could get some of these cells. Using PbA, MG range is ~30 mi; using LiFe, it's ~80 mi. (more if I wanted to put in the same weight of Li as needed for PbA); it's ~200 mi. using these new Si-anode cells which is the range reported by several ICE MG drivers.


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## IamIan (Mar 29, 2009)

RE Farmer said:


> Mostly, I wanted to show that energy densities are improving. I forecast (possibly on a previous thread you started) that EV range capabilities will double, or better, every 2 yrs.


Improving yes ... but 2x every ~2 years ... I think that is extremely optimistic.

But , only time will tell I guess.

In the mean time we'll make do with what is reasonably available now ... which is several years behind current state of the art ... and Current State of the art which is also several years behind the cutting edge Electrochemical Scientific research.... etc.


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## PhantomPholly (Aug 20, 2008)

RE Farmer said:


> I wasn't trying implying that they were ready for prime time as these craft were purpose built for the CAFE competition. But, 2 hr duration for a 4-place craft is impressive, and even more so was the fact that they beat the snot out of the dino-powered craft. Essentially, I was trying to address your question on the state-of-the-art of EV vs. ICE-powered vehicles.


I wasn't poo-poohing the accomplishment, nor was my sarcasm directed at you. It's simply disappointment that it takes state-of-the-art simply to get these birds aloft for under 2 hrs. As others mentioned, up to a certain point the lighter components offset the heavier "fuel;" however, beyond that starting point it adding range is at a 30x premium compared to gas. The airplane nearest and dearest to my heart cruises at twice the speed of the Cafe planes with a range of about 1,000 statute miles. That is going to be a long ways off for batteries.



> While I don't have first hand data, my understanding is these cells drop to 70% capacity @ ~300 cycles then remain around that capacity for another couple thousand cycles. Mostly, I wanted to show that energy densities are improving. I forecast (possibly on a previous thread you started) that EV range capabilities will double, or better, every 2 yrs.


The current rate is only around 5-10% per year. At those rates it will take about 6-10 years to double capacity. We need a breakthrough.



> I concur with the 30X current difference between ICE and EV effective energy densities. Assuming the 30X difference and my doubling forecast, we would have parity in ~8-10 yrs. (2^5 = 32X; 5*2 = 10yrs). My MG would almost be there if I could get some of these cells. Using PbA, MG range is ~30 mi; using LiFe, it's ~80 mi. (more if I wanted to put in the same weight of Li as needed for PbA); it's ~200 mi. using these new Si-anode cells which is the range reported by several ICE MG drivers.


See above - I don't remember who posted it, but there was a nice chart showing slightly over 5% improvement per year.


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## RE Farmer (Aug 8, 2009)

PhantomPholly said:


> I wasn't poo-poohing the accomplishment, nor was my sarcasm directed at you. It's simply disappointment that it takes state-of-the-art simply to get these birds aloft for under 2 hrs. As others mentioned, up to a certain point the lighter components offset the heavier "fuel;" however, beyond that starting point it adding range is at a 30x premium compared to gas. The airplane nearest and dearest to my heart cruises at twice the speed of the Cafe planes with a range of about 1,000 statute miles. That is going to be a long ways off for batteries.
> 
> The current rate is only around 5-10% per year. At those rates it will take about 6-10 years to double capacity. We need a breakthrough.
> 
> See above - I don't remember who posted it, but there was a nice chart showing slightly over 5% improvement per year.


Pholly, no offense taken.... 

Granted I only have three data points, and it is poor science to generalize from such a small data set; but I started planning my MG conversion in 2008 using PbA and scratching my head to figure how to get at least 35 mi. range. Then LiFe cells became commercially available in 2008-9, easily doubling my range to 70+ mi. Now, Si-anodes cells offer ANOTHER doubling+ in 2011-2. The doubling is coming and will come from technology advances not the 5% improvements due to better manufacturing processes.

I may seem to be a bit optimistic, but we've only just started to apply serious research into large format storage. And the research is coming from the electric power industry for intermittent renewables (think wind and solar), the auto industries and both commercial and amateur EV builders of cars and aircraft. Consider that prior two years ago electric flight was utter folly due to the weight. Now there are several individuals/companies with one to several different craft in the air and more on the way. Yeah, I would like 1000 mi. range at 200 mph right now, but considering most people's build times you need to start planning now for the batteries that will meet that specification by 2020.


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## IamIan (Mar 29, 2009)

PhantomPholly said:


> The current rate is only around 5-10% per year. At those rates it will take about 6-10 years to double capacity. We need a breakthrough.


While a breakthrough would be nice ... I have my doubts.

Maybe I'm just being overly conservative ... but ... I expect a few small spikes here and there ... but overall ... I expect the average rate might increase a little bit ... with the growing rechargeable battery market ... and scientific progress ... but I expect to see sustained rates bellow ~20% increases per year for the next ~50 years or so... and I would not be at all surprised by only an average of ~5% yearly increases either.



RE Farmer said:


> considering most people's build times you need to start planning now for the batteries that will meet that specification by 2020.


I'd recommend not building your design to require products that do not exist yet... and may never exist.

If current State of the Art isn't good enough ... I'd put the project on the shelf ... maybe come back to it every couple of years to see where things are.


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## PhantomPholly (Aug 20, 2008)

RE Farmer said:


> Pholly, no offense taken....
> 
> Granted I only have three data points, and it is poor science to generalize from such a small data set; but I started planning my MG conversion in 2008 using PbA and scratching my head to figure how to get at least 35 mi. range. Then LiFe cells became commercially available in 2008-9, easily doubling my range to 70+ mi. Now, Si-anodes cells offer ANOTHER doubling+ in 2011-2. The doubling is coming and will come from technology advances not the 5% improvements due to better manufacturing processes.
> 
> I may seem to be a bit optimistic, but we've only just started to apply serious research into large format storage. And the research is coming from the electric power industry for intermittent renewables (think wind and solar), the auto industries and both commercial and amateur EV builders of cars and aircraft. Consider that prior two years ago electric flight was utter folly due to the weight. Now there are several individuals/companies with one to several different craft in the air and more on the way. Yeah, I would like 1000 mi. range at 200 mph right now, but considering most people's build times you need to start planning now for the batteries that will meet that specification by 2020.


Yep, we may move that fast but it will take breakthroughs, not incremental tweaks.

This may be one - promise of 10x energy-density increase using flourides instead of LiIon. At 3x disadvantage but factoring in motor weight and cooling drag savings, 1,000 miles might again be within reach in flight.


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## Sunking (Aug 10, 2009)

dougingraham said:


> This means 40.8kw. At 90% efficiency this drops to 36.7kw and you ought to be able to do better than 90%. So you can charge your 20kwh pack to 80% in 26 minutes.


Do not confuse the size of your AC service with how much you can draw continuously because they are not related.

If you go outside, look for your service transformer and look at the KVA rating. If it is a single service transformer it is likely a 15 to 20 Kva transformer. If it is shared with say with say 2 service drops it is likely a 30 Kva transformer.


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