# Please explain if this is right, or where it is wrong.



## redshadowz (Dec 8, 2012)

I was running through some numbers and it feels like I must be getting something wrong, otherwise it is seemingly too good.


The Chevy EV1 supposedly had about a 16.5 kwh battery pack of 26 batteries. Each 12v battery would have only been about 53 amp hours. Total voltage was 312 volts. That car weighed ~3100 pounds, probably which ~1100 pounds was just battery alone. And had a range of up to 90 miles per charge. I assume the 90 mile range was at around 45 mph.

If you assume 53 amp hours, with a ~95% efficient motor, being drained over the course of two hours. That would mean ~26.5 amps being drawn per battery. Giving the total efficiency of the cars powertrain at between 80-85%. Which means the power out of the engine would have been about 6.6kw-7kw(8.8-9.33 horsepower).

Basically, 9 horsepower to push 3,100 pounds at 45 miles per hour.


I used the spreadsheet off this mans project and put in place the relevant numbers for the EV1.... motorcycle dry 1900, misc mass 60, motor 100, frontal Area to 960(6.67 square feet), Air drag .16, motor efficiency .95, Bus voltage 312, number of batteries 26, voltage of battery 12, mass of battery 40 pounds, battery life 400 cycles, amp-hr @ 60 minutes 40.... It spit out 163.68 WH per mile, 7300 watts used by the engine, which leaves 76.24 miles of range. Which is pretty close to my assumptions.

http://www.electricmotion.org/


If you then change the electric cost to 12 cents a KWH... and the total cost of the battery pack would be about $2,000. That puts the price per mile at 9 cents(vs about 9 cents a mile for a 40 mpg car with $3.20 gas). At 8 cents a KWH, its only 8.19 cents per mile, compared to 9 cents... But thats assuming only 400 charge cycles. The AGM batteries that GM used might have been able to recharge 600-800 times. And at 800 times at 8 cent kwh electric, that pushes the cost down to only 4.92 cents per mile(vs 9 cents a mile for gas).



I used the spreadsheet more, and thought, what if I converted a Honda Civic HB from the early 90's(they already got great gas mileage, so I wanted to use them as the base)... motorcycle dry 1800, misc mass 60, motor 100, frontal Area to 960(6.67 square feet), Air drag .32, motor efficiency .85, Bus voltage 144, number of batteries 12, voltage of battery 12, mass of battery 50 pounds, battery life 400 cycles, amp-hr @ 60 minutes 80...

It would use this battery... 

http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212

With those specs, it claims it would have an effective range of 66.16 miles(174.13 watt hours per mile vs 163.68 for the EV1). With the engine pushing about 7850 watts(10.5 hp) And with 8 cent gas, and a $1000 battery pack, it would cost 5.52 cents a mile(vs the aforementioned 9 cents a mile). 

Based on the calculations, the civic would get about 26,500 miles on the battery pack. Which means that the cost of driving 26,500 miles would be about $1,463, vs $2385 for conventional gas. A difference of $922.... So if the cost of conversion of all materials minus the batteries, cost at or less than $922. You could potentially recoup your investment in basically 25k miles or less?



That seems a little too good to be true. So it must be wrong? Is it really true that the EV1 only used about 9-10 horsepower to push 3,100 pounds at 45 mph? Would it only require about 10-11 horsepower to push 2,600 pounds of Honda Civic at 45 mph?

When I was reading about other conversions, it seemed like most were needing about twice as much power per mile(about 400 watts per mile). And that would effectively double the cost of power, which would push the overall cost of an electric car, higher than gasoline.


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## Ziggythewiz (May 16, 2010)

There's a huge difference between cruising wh/m as you would do for max range vs average wh/m for a typical stop&go commute. My bug is around 10 hp to cruise at 45 mph, but average usage is double that.

Any EV that's not running LiFePO4 or similar with 2-3000+ cycle life is not going to fare well in a straight economic comparison with a 40 MPG gasser. No surprise there.

And why would your conversion (minus batteries) cost under $922? That's not realistic, nor even close.


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## Caps18 (Jun 8, 2008)

The GM EV1 could only do about 90 miles in good conditions (1.5 hours) or 70 miles normally (1 hour). They do need to remake the EV1 with LiFePO4 batteries though. Give it a 200 mile range, fast charging like Tesla, and a reasonable price.

And the weight of the car impacts the Watts/mi numbers a lot.

There are other benefits then just saving money to converting a car to electric as well. My 40mpg car has had a new alternator, fan belt, 1qt. oil every 400 miles, muffler & catalytic converter, and air filters. Not to mention the oil changes in just the past 5 years. And I hardly drive it. I pay more in insurance on a 17 year old car than in gas over the summers...(<$150)


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## redshadowz (Dec 8, 2012)

Well, I'm confused on Lifepo4.

It seems like, a Lifepo4 battery costs about $.75-$1.25 per watt hour(though, there are some Chinese made batteries that are closer to 30 cents per watt hour).

This battery from Wal-mart is effectively 1,380 watt hours for ~$80, or 5.8 cents per watt hour.

http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212

Even if you assumed that the Wal-mart battery only had 300 cycles at 80% DOD. The number of cycles for a Lifepo4 at 80% DOD is generally only 1000-2000 cycles. So roughly 3-6 times as many cycles. Then over a period of time you would need to buy 3-6 times as many Wal-mart batteries, pushing the real price to 17.4 cents to 34.8 cents per watt hour.

Even if you factor in the weight differential(which for larger projects generally isn't going to drastically reduce performance), and the relative loss of inefficiency by draining a lead-acid battery at a high rate(anything above 25 amps is going to lead to huge inefficiencies). It still won't make up the price difference.

It seems like the break even point for a lifepo4 would be maybe 20-50 cents a watt hour, depending on the amp draw of the project, and the average DoD.... 

Unless you know of a source that can get lifepo4's for less than 30 cents per watt hour, I just don't see the point, unless you are concerned about weight.


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## Caps18 (Jun 8, 2008)

Weight is very important. A basic rule of thumb is that for every 100 lbs you add, it takes 10W/mi to move it. Plus being able to carry more range means that you won't be as likely to drain it to 80% DOD as often. Making the battery last a lot longer. 

Plus, not having to change out heavy batteries every few years is a good thing too. (and I'm not sure if there are any real world examples of LiFePO4 performance to determine lifetime, so it could be higher even.)

It isn't to say that for people with very limited budgets in warm climates, that didn't need to go very far, that lead acid wouldn't be a cheap way to go for a few years though.


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## major (Apr 4, 2008)

redshadowz said:


> This battery from Wal-mart is effectively 1,380 watt hours for ~$80, or 5.8 cents per watt hour.
> 
> http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212
> 
> Even if you assumed that the Wal-mart battery only had 300 cycles at 80% DOD.


Hi reds,

You're in a dream world with this battery spec. The real world is a lot different. See this: http://www.diyelectriccar.com/forums/showthread.php?t=78826 And note the last post for the old batteries which were likely cycled less than 100 times. I doubt the WallyMart product is even close to that quality or even real deep cycle batteries.

Not all Pb-Acid is bad. You get what you pay for and it is what it is. Also not all LiFePO4 is good. But we have seen some very encouraging reports from members like tomo. http://www.diyelectriccar.com/forums/showpost.php?p=335188&postcount=656 

Regards,

major


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## Ziggythewiz (May 16, 2010)

redshadowz said:


> This battery from Wal-mart is effectively 1,380 watt hours for ~$80, or 5.8 cents per watt hour.
> 
> http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212
> 
> Even if you assumed that the Wal-mart battery only had 300 cycles at 80% DOD. The number of cycles for a Lifepo4 at 80% DOD is generally only 1000-2000 cycles. So roughly 3-6 times as many cycles. Then over a period of time you would need to buy 3-6 times as many Wal-mart batteries, pushing the real price to 17.4 cents to 34.8 cents per watt hour.


You can use 30-40% of sticker AH from lead acid. 70-80% for LiFePO4. Some cells are rated for 2000, 3000, even 5000 cycles when used in that range.


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## PStechPaul (May 1, 2012)

I have an on-line calculator that figures the actual A-h for lead acid batteries based on the Peukert factor. The actual A-h is about 1/2 rated for 1C current draw. Also, if you read the reviews of the Walmart battery, there have been some serious problems. 

Lead-acid can be as low as $0.06/Wh and SLAs about $0.16/Wh. But if you figure usable capacity and half the lifetime of LiFePO4, you get $0.24 and $0.64. High quality lead acid cells are more expensive than the SLAs, although Peukert and life may be a little better. Calb LiFePO4 cells are advertised at $0.42 and there are better deals available.


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## redshadowz (Dec 8, 2012)

Ziggythewiz said:


> You can use 30-40% of sticker AH from lead acid. 70-80% for LiFePO4. Some cells are rated for 2000, 3000, even 5000 cycles when used in that range.


Well, I think some of the people around here are really exaggerating the inefficiency of a lead-acid battery. There is no doubt that heavy loads will drop the efficiency down considerably from what its rated at. But I've never seen anyone put the rating anywhere near 30% at anywhere near normal loads.


Generally the rated efficiency for a battery pulling 25 amps is about 80-85%. For a comparison, the EV1 would have use only about 25 amps to push about 10.5 horsepower(7.7kw). If the efficiency of the EV1 battery bank would have been 30-40% like you stated, the EV1 would have pushed around 3100lbs plus a driver at 45 MPH, with only 4 horsepower(3000 watts). Which is simply impossible in reality. People were getting more like 70 miles at highway speeds for one hour. The battery bank for the EV1 was 16.5kwh, which means at 30% efficiency, the engine was putting out a whopping 5kwh, which is about 6.6 horsepower. It is simply impossible for the EV1 to have pushed a 3100 pound vehicle to 70 mph with only 6.6 horsepower. 

The reality is that, higher-quality lead-acid batteries with discharge rates of 25 amps should be able to get at least 80% of design spec. Lets be honest here. Lead Acid batteries have been around for over a hundred years, but there is not a single reputable site that I have ever seen that lists the conversion efficiency anywhere near 30-40%. And the battery manufacturers would be arrested for fraud if their numbers were so far off.


With that said, I see some potential for Lifepo4, but they also aren't 100% efficient in terms of discharge. It seems to me, that the break-even point for a lifepo4 as compared to a lead-acid battery would have to be three to six times the cost of the lead-acid battery per WH. So, if a lead-acid battery costs 6 to 10 cents per watt hour, the lifepo4 would need to be 18-36 to 30-60 cents per watt hour.

Basically, 60 cents per watt hour for Lifepo4 seems like the absolute maximum. And the cheapest you can buy them domestically seems to be about 75 cents per watt hour. You can buy them from China for as little as 30 cents per watt hour, but will most likely only get about 1500-2000 charges. Which puts the cost for lifepo4 somewhere between 50% more expensive than lead acid batteries, or half the price.

But that is only if you use cheap Chinese lifepo4's. If you buy American, lifepo4 will be between 25% more expensive, and as much as five times more expensive.


Unless of course, the American Lifepo4's give more than 2,000 cycles at 80% DOD. Which is doubtful. Most Lifepo4's only get about 1,000 cycles at 80% DOD. Then 2,000 at 60% DOD, and like 5,000 at 30% DOD.

If we are talking only 30% DOD, some lead-acid batteries get over 1000 cycles.


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## redshadowz (Dec 8, 2012)

PStechPaul said:


> I have an on-line calculator that figures the actual A-h for lead acid batteries based on the Peukert factor. The actual A-h is about 1/2 rated for 1C current draw. Also, if you read the reviews of the Walmart battery, there have been some serious problems.
> 
> Lead-acid can be as low as $0.06/Wh and SLAs about $0.16/Wh. But if you figure usable capacity and half the lifetime of LiFePO4, you get $0.24 and $0.64. High quality lead acid cells are more expensive than the SLAs, although Peukert and life may be a little better. Calb LiFePO4 cells are advertised at $0.42 and there are better deals available.



Well, I think your calculator needs some work. Tweaking the numbers, it puts far too much emphasis on acceleration. It is effectively the only stat that matters.

If you give it the relative specs of an EV1(1500kg, .16 CoD), and set acceleration to .05. It gives roughly the actual WH draw of the EV1(~180 wh per mile). If you leave it at 1, it spits out ~820 wh per mile. That is the relative difference between getting 10 mile of range per charge and 45.5 miles of range per charge.

Basically, the problem with the calculator is that it assumes that a person is constantly accelerating, never cruising.

Moreover, at the end if you set amp hours to 115, and then set the battery current to 25 amps. It spits out ~83% efficiency.

I assumed that the EV1, based on its battery pack, used about 7.3kw to get 90 miles out of a charge. It was a 312 volt battery pack, which means it was only pulling 23.4 amps. Which based on your formula, would net an 84.2% efficiency.


The problem is, the difference in price of the battery I was looking at, and the cheapest Lifepo4, is about 8.5 times. And the more expensive Lifepo4's are more like 17 times the price of the lead-acid battery.

The question is, how does the lifepo4 make up that kind of difference? If operated at low amps, the efficiency of a lead-acid battery is about the same as a lifepo4(80-85%). And depending on the driver, the life expectancy should be between half to a fourth of a lifepo4. Meaning that the lifepo4 should still be at least twice as expensive over time under specific conditions.


The only time a lifepo4 seems to be better(price-wise), are in applications with high amperage, and at least one relatively deep charge cycle every single day.

Otherwise, it seems to be more an issue of convenience and weight. For instance, I thought it would be neat to make an electric motorcycle. But because of weight limitations, it would be impossible to convert a small motorcycle to electric using lead-acid. To push even a small motorcycle to reasonable speeds, would require between 5-10 horsepower. But you wouldn't want to add more than 100 pounds to the weight of a motorcycle. Giving you maybe 140 pounds of batteries(after removing the engine/exhaust/etc). That would only allow about four 50 amp hour batteries at most. To push 10 horsepower(my 200 cc motorcycled pushed 13 peak), would require 7500 watts, with 48 volts from the batteries, would require 156 amps. That kind of current draw would drain those small batteries in 15 minutes.

Basically, for a motorcycle, the weight is just too prohibitive to go lead-acid. But I would assume a small car could accommodate more weight without being nearly as much a burden. For instance, a 92 civic hatchback weighs only 2100 pounds. The EV1 weighed 3100 pounds... If you converted the Civic, it would weigh probably about the same as the EV1, maybe a little more. Which would make it feel like a Civic with five adults sitting in it. Basically, would feel very "heavy", and would be more difficult to get moving and to stop. Might benefit from a new suspension and better brakes, but should otherwise be ok. Right?


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## PStechPaul (May 1, 2012)

I found that the cheapest lead-acid batteries, like the Walmart $85 100 Ah you listed, is about $0.06/Wh, while the Calb LiFePO4 cells are about $0.42/Wh, so only 7x the cost. But if you run the lead at about 1C, the Peukert cuts the Ah in half, and if the lithium lasts 4x as long, they come out cheaper, even ignoring the weight issue. Also, flooded lead acid may be a safety hazard in an EV for high speed highway use in case of an accident. If you use SLA types, the cost is 2-3 times that of the floodies, and the high-end AGM types are actually much higher, something like $0.60/Wh.

Just a quick note about the calculator. At higher speeds with 0 acceleration you can see the effects of aerodynamic and rolling resistance. Also remember that a slope is the same as acceleration, so a 5% grade is 9.8 * 0.05 = 0.049. If you want to see what it takes to accelerate from, say, 0 to 60 MPH, you should set speed at the average 30 MPH. Otherwise it will tell you that the power is zero. This is actually correct if the vehicle is not moving but is on a slope. It is accelerating due to gravity so it takes force to keep it from moving. 

My calculator might not be totally correct, but it seems close enough for most purposes, and I find it easier to use than other EV calculators. If you have any corrections or enhancements you would like to see, I would welcome that. The calculations are performed using JavaScript, and it is otherwise just simple HTML, so feel free to modify it as you wish. If so, please let me know and I'll update mine for all to use. 

I was originally convinced that lead-acid batteries were much cheaper than LiFePO4, but I learned that the Peukert factor and shorter life, as well as more weight, made them fairly comparable in effective capacity and $/Wh, at least for a practical electric car. But for a tractor, which is usually used only a few hours a week, and where extra weight is a bonus, the lead-acid batteries are much more economical and practical.


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## major (Apr 4, 2008)

redshadowz said:


> Well, I think some of the people around here are really exaggerating the inefficiency of a lead-acid battery. There is no doubt that heavy loads will drop the efficiency down considerably from what its rated at. But I've never seen anyone put the rating anywhere near 30% at anywhere near normal loads.
> <snip>
> The reality is that, higher-quality lead-acid batteries with discharge rates of 25 amps should be able to get at least 80% of design spec. Lets be honest here. Lead Acid batteries have been around for over a hundred years, but there is not a single reputable site that I have ever seen that lists the conversion efficiency anywhere near 30-40%. And the battery manufacturers would be arrested for fraud if their numbers were so far off.


Hey reds,

I did not exaggerate anything in that reference thread showing "real life lead acid".

Here you use a about 0.75C rate.


redshadowz said:


> voltage of battery 12, mass of battery 50 pounds, battery life 400 cycles, amp-hr @ 60 minutes 80...
> 
> It would use this battery...
> 
> http://www.walmart.com/ip/EverStart-27DC-6-Marine-Battery/16795212


 That is close to the test I did in the referenced thread. http://www.diyelectriccar.com/forums/showthread.php?t=78826 

Have you ever load tested a battery for capacity? I suggest you do so with a sample of those WallyMart specials.

As for the battery manufacturer specification fraud, it has been grandfathered in and they are granted exemption from truth  Don't get fooled. Test for yourself.

Regards,

major


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## Ziggythewiz (May 16, 2010)

redshadowz said:


> Well, I think some of the people around here are really exaggerating the inefficiency of a lead-acid battery.


Maybe some of us have actually used dozens of them? It's not just the efficiency that takes it down to 30%. For long life it is recommended to use 50% DOD or less, then peukert takes another 30-50%. 

For comparison, don't reference the EV1. How many of those are on the road today? If my unicorn were only 30-40% efficient...




redshadowz said:


> The reality is that, higher-quality lead-acid batteries with discharge rates of 25 amps should be able to get at least 80% of design spec.


The reality is that higher-quality lead-acid batteries are not the cheapest wallyworld batteries that you're basing your math on. The good ones cost nearly what lithium does. 



redshadowz said:


> But that is only if you use cheap Chinese lifepo4's. If you buy American, lifepo4 will be between 25% more expensive, and as much as five times more expensive.


Who are all these American LiFePO4 battery makers you're referencing Mr. Obama? Everyone gets LiFePO4 from China.


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## redshadowz (Dec 8, 2012)

Well, I did a rather long "feasibility" survey of a variety of types of electric vehicles.


Over the course of my investigation. I became more and more disappointed.

I went in with the EV1 in my head. But as time goes on, I realize that the EV1 is sort of an anomaly, and probably isn't realistic to assume you can get anywhere close to the EV1 from a conversion.


The EV1 had a drag coefficient/drag area about half the size of a standard economy car. And the EV1 was an AC motor with regenerative braking. Effectively, its impossible to get anywhere near the specs of the EV1 through a conversion.

So what can you get? Well, you really have two choices from the outset. Lead-acid batteries or Lifepo4.

If one was to go down the road of Lead-acid. The problem really comes in the form of the peukert effect, which basically means your range will be crap unless you can keep your amp draw to less than 30 amps. So many people seem to think its a good idea to get golf cart batteries of 6v, and run 96v with 16 batteries.

To get realistic acceleration, you would need about 20-30 horsepower(depending on the overall weight of the vehicle, the coefficients of the vehicle, and how fast one wants to accelerate). At 20 horsepower, you are pulling 15kw, which at 96v is 156 amps. Which is many times higher than the 30 amps desired. Which at that amperage, you will get maybe 1/3rd the life of a battery.

The EV1 only needed about 200 watts per mile. Most conversions of lead-acid batteries of 144 volts or less, seem to be using about 400-600 watts per mile. 

A typical battery pack is about 15-20kwh. So at 200 watts per mile, you would get about 75-100 miles from a battery pack. But at 500 watts, you would only get 30-40 miles from a battery pack. And that will most likely be at more "city" speeds of around 45 mph.

If you could emulate the EV1 with a lightweight and aerodynamic car. By putting in 300+ volts of 12v batteries, running regenerative braking off an AC motor. You could still probably achieve the 250 watt per mile range. But the cost of converting that car would be astronomical. Just the DC to AC inverter/motor controller would cost several thousand dollars. The motor would cost a couple thousand as well. After adding all of these things up, you will have spend between $10-$25k to convert the car. It would be nearly impossible to recoup that money from energy savings.



The problem is that, at 500 watt per mile. To travel 40 miles would require 20 kwh of electricity. Which would cost about $2. That would actually require about 1.6 cycles of a 15kwh battery pack, because you don't want to drop below 80% DoD... If you expect to get 500 cycles at 80%, and your battery pack cost $1,200(12 batteries, $100 each)... That would cost about $3.84 in battery cost to go that 40 miles(1200/500*1.6). So, the total cost to go 40 miles at 500 watts per mile, would be $5.84, compared to about $3.20 for gas... Even if you factor in oil and all the other expenses for an ICE car, it doesn't make up the difference.

Of course, if you could operate at 200 watts per mile. It would only cost 8kwh(80 cents) to go 40 miles. A 15kwh battery pack at 80% DoD(12kwh) could travel 60 miles, so 40 miles would only require 2/3rds of a "cycle". If a cycle cost $2.40, then it would cost only $1.60 a cycle in battery. And $.80 in electric, or $2.40 total. But then the price difference is only 80 cents for 40 miles, or 2 cents a mile... If it cost you $15k to convert, it would take 750,000 miles to recoup the investment.

Effectively, total conversion cost could not be more than $3k, and watt/hour per mile couldn't be more than 250 to ever be able to realistically recoup your investment.

Its really impossible to achieve both.


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## PStechPaul (May 1, 2012)

I think you may be mistaken about the cost of an AC system, if you have a good set of DIY electronic skills. You can get a suitable industrial motor and controller for well under $2000. And if you choose a lightweight aerodynamic vehicle that gets 35+ MPG with its ICE, I think you should be able to achieve 250-300 Wh/mile, and maybe better if you drive carefully and if the regen is effective. 

When I first came here I thought Lead-Acid batteries would be much cheaper than Lithium, but in the long run (over 5-10 years) the Lithium may be cheaper and more reliable, and the car's performance will be much better without 1000 lb of lead. Weight is good for tractors - cars at highway speeds - not so much. 

However, I may still make my first EV car with SLA batteries, say 30 of the 12V 12Ah which are about 12lb each and $20, so $600 and 360 lb for a 360V system with 4.3 kWh. I realize that would only give me about 5 miles of range but it would be enough for evaluation. Then I could get 100 pieces of 40 Ah LiFePO4 at $54 each for $5400 and I'd have a 13.2 kWh pack that might give me a respectable 40 mile range.


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## redshadowz (Dec 8, 2012)

PStechPaul said:


> However, I may still make my first EV car with SLA batteries, say 30 of the 12V 12Ah which are about 12lb each and $20, so $600 and 360 lb for a 360V system with 4.3 kWh. I realize that would only give me about 5 miles of range but it would be enough for evaluation. Then I could get 100 pieces of 40 Ah LiFePO4 at $54 each for $5400 and I'd have a 13.2 kWh pack that might give me a respectable 40 mile range.


Regardless, even under "ideal" conditions. At 300 watts per mile, to travel 40 miles would take 12kwh($1.20 where I live), plus one whole "Cycle" of a 15kwh battery pack at 80% DoD... With an expectation of 500 80% DoD cycles, and twelve batteries at $100 a battery. It would cost $2.40 for one cycle. So total cost even at 300 watts per mile, would be $3.60 for 40 miles. Gas right now is about $3 a gallon where I live. Thus you would lose money.

The sort of break-even point for lead-acid batteries over the course of say 100k miles, would be something like 250 watt hour per mile with a $2000 conversion cost. But it would be practically impossible to achieve anything close to 250 watt hours per mile, unless you had something like the aerodynamic drag coefficient of the EV1. Or were using an AC motor with regenerative braking and high voltage. 

To do those things, would increase the cost of conversion far beyond the $2000 threshold. And would simply be impossible to recoup the investment... Which is disappointing.

I had originally hoped to spend about $1000 max to do a conversion(minus the batteries), that would utilize some kind of high-efficiency series wound forklift motor. About twelve wal-mart marine batteries for $80 a piece(12v 115 amp hours, 16.56 kwh). And would have only used about 200 watt hours per mile... To travel 40 miles at those specs would have cost 80 cents in electricity, and would have cost $1.15 in battery depreciation. Or $1.95 a mile... Which would have saving me about 2.5 cents a mile, plus savings on oil changes and the like. Probably about 3 cents a mile in real savings. The $1000 up front cost could have been paid for in about 30k miles. Possibly ultimately saving me up to $500 a year from the third year onwards. 

But that just seems to be basically unrealistic.


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## PStechPaul (May 1, 2012)

If you base everything on economic terms, EVs are still a losing proposition, but you need to add the value of accomplishing a task, learning things, setting a good example, and reducing carbon footprint. But there are other things to consider as well. 

For the AC system, you can get a 30 HP motor for about $300:
http://www.ebay.com/itm/GE-5KW286AD205-30hp-electric-motor-200v-230-460v-1800rpm-nice-/181043257122

And a VFD for about $1000 or less:
http://www.ebay.com/itm/290801028404
http://www.ebay.com/itm/230769887466
http://www.ebay.com/itm/140853190068
http://www.ebay.com/itm/120897984511

Unless they are abused or severely modified, they will still be usable for another conversion or resale, and an AC motor's maintenance is minimal. So whatever you spend is an investment with lasting intrinsic value. 

The only real consumable is the battery pack, and it may also have some scrap value or additional usefulness as a solar panel storage once their capacity limits the range too much. Lithium cells may last 20 years if you can tolerate 50% capacity. Stationary energy storage does not have the size and weight constraints that vehicular use impose. 

So, really, an initial investment of, say, $10,000 would still be worth perhaps $5000 after ten years, and if gas prices reach $10/gallon by then (which is extremely likely), electric cars will be the economic choice.


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## redshadowz (Dec 8, 2012)

If we look at Lifepo4. It is very realistic to get 200-300 watts per mile, even with a DC motor. So you might be able to get by with some cheap old forklift motor, cheap controller, etc. But all hardware would still probably at minimum cost $1k, but more reasonably but still economically might cost around $3k.

The Lifepo4, you'll pay about 40-50 cents for 1 watt hour, for cheap Lifepo4's from China. At 45 cents a watt hour, you'll probably want to buy at least a 15000 wh battery pack. Which would cost $6750 for the battery pack. Giving you a total cost of about $8k-10k in conversion costs.

At 250 watts per mile. It would cost $1 in electric to travel 40 miles. If the battery pack lasted 2000 charges to 80% DoD, it would cost $3.37 per recharge cycle. If we say 80% of 15kwh is 12kwh, and to travel 40 miles takes 10kwh at 250 watts per mile. Then it would take 83.33% of a charge to travel 40 miles. Which would cost $2.81 per charge in battery, and $1 for electricity. Thus the total cost would be $3.81 to travel 40 miles. Even if you factored in oil changes and other costs. Its difficult to believe you could make up the difference.

And the sad reality is that, it is difficult to believe that you could get 250 watts per mile on average, unless you drove very conservatively.


If we were to say, we wanted the car to be able to pay off its investment costs in say, 100,000 miles. What would the costs need to be for the conversion and the battery?

Well, to pay off $3000(300,000 pennies) investment in 100,000 miles, would require an average savings of 3 cents a mile. That would equate to $1.20 per 40 miles. If we peg gas at $3.2 a gallon, then the total cost of driving 40 miles would need to cost no more than $2... If it costs $1 in electric at 250 watt hours per mile.... Then the cost of the battery pack couldn't be more than $1 to travel 40 miles...

If it takes 10kwh to travel 40 miles, you would need a 12.5kwh battery pack if you only wanted to use 80% of depth of charge per cycle. To keep costs of a 12500 watt hour battery to only $1 a cycle, would require 16 cents a watt hour Lifepo4's, capable of 2000 charges at 80% DoD.


Even if you could somehow lower your conversion costs to about $1000 minus the battery pack. The battery pack could only cost $1.80 a cycle for a 12.5kwh battery pack. That would mean the most you could pay for Lifepo4's would be 28.8 cent a watt hour.


In conclusion, at current prices, it is effectively impossible to recoup your investment on a conversion using Lifepo4 battery packs even over the course of 100,000 miles... And more importantly, around 99% of the electric conversions I have seen, would never be able to recoup the investment. And would rather be a big money sink.


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## Ziggythewiz (May 16, 2010)

A $5k lithium pack can easily do 35 miles at 70% DOD. That pack should last 3000 cycles according to spec. That means it = 3000 gallons of gas (compared to a 35 mpg car), or over $10k at $3.50, $12k @ $4, $15k @ $5 (where gas will be long before that lithium pack wears out).

The savings is there but takes years to realize.

Economics all depend on opportunity costs, so in my case I would compare it to my minivan, more than doubling all the savings above.


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## redshadowz (Dec 8, 2012)

Ziggythewiz said:


> A $5k lithium pack can easily do 35 miles at 70% DOD. That pack should last 3000 cycles according to spec. That means it = 3000 gallons of gas (compared to a 35 mpg car), or over $10k at $3.50, $12k @ $4, $15k @ $5 (where gas will be long before that lithium pack wears out).
> 
> The savings is there but takes years to realize.
> 
> Economics all depend on opportunity costs, so in my case I would compare it to my minivan, more than doubling all the savings above.


Well, a $5k battery pack for 35 miles would need to be about 12kwh pack, which would cost about 40 cent a watt hour for Lifepo4's. Which might be about the right price, but a little under.

To get 3000 charges with such a pack, would mean you drove 105,000 miles. For a cost of 4.76 cents a mile in battery. To charge a 12kwh pack would require probably 13.2 kwh, or ~$1.32(3.77 cents a mile).. Total cost 8.53 cents a mile... A 35 mpg car at $3.20 with a $30 oil change every 3000 miles, would cost 10.14 cents a mile. A difference of 1.61 cents a mile.

After 100,000 miles, that would be $1610... Basically, at 40 cents a watt hour of lifepo4(which is cheap), after 100,000 miles, you would recoup $1600, and after 200,000 miles you would only recoup $3200.

The break even point on the battery pack at 3000 charges would be 6.37 cents a mile, or about 53 cents a watt hour for a lifepo4 battery pack. 


The problem is that, a lot of people are paying more than the break-even point of lifepo4 of 53 cents a watt hour at 3000 cycles. And that break even point would be 35.6 cents per watt hour for lifepo4 at 2000 cycles.

And whats worse, is that many people are paying huge sums of money to convert their cars. Many people are spending upwards of $10k, not even including batteries. So, if you go back to the figures of if you were getting 3000 cycles at 40 cents a watt hour of lifepo4. It would take about 600,000 miles to recoup a $10k investment in motors/controllers/chargers etc.

And I would say that 90% of EV conversions never even see the 100,000 mile mark.


Basically, it seems to me that 99% of EV conversions, are really people throwing money away.


As for converting larger vehicles and getting exponential savings. It simply isn't true. The problem is that relative efficiency isn't going to change in a large vehicle. If a small car gets 40 mpg, then it might take 250 watt hours to run it. If a large car gets 20 mpg, then it might take 500 watt hours to run it. 

The only things that might allow you to save money over the long run. Is that the conversion costs of a 20 mpg vehicle won't be twice the cost of a 40 mpg vehicle. And the "accessories" of a 20 mpg vehicle won't be any different than a 40 mpg vehicle(lights, radio, etc).

The problem is, you would need twice the batteries, which will offset those benefits by the extra weight. If there was a benefit to converting larger vehicles at all, it would be minimal. In fact, it seems the economics generally tend to point in the opposite direction. With large vehicles being increasingly more expensive because of the increased weight/drag.


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## major (Apr 4, 2008)

Hi reds,

I have my own reasons for building and driving EVs. But I do take an interest in the value of such. Part of that value is economics. You seem to dwell on it. Here are a couple of links which I found interesting.

http://greentransportation.info/electric-vehicles-are-cheaper-to-drive-or-operate-than-gasol

http://evamerica.com/eveconomics.pdf 

I hope you convince yourself it's worth it.

Regards,

major


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## TigerNut (Dec 18, 2009)

Parasitic losses and parasitic costs both favor the larger conversions. The cost per kW of drive capability, both in the motor and the controller, goes down pretty steeply within the same classes of components; and you need a charger for small and large conversions alike.

So far as range is concerned, a few mileage mods can push a larger ice car from, say, 20 to 25 miles per gallon. To drive 100 miles you'd need four gallons instead of five, saving one gallon. A 40 mpg car uses 2.5 gallons of gas to go 100 miles; saving one gallon per 100 miles would require you to improve its mileage to 66 mpg... Much more difficult. 

The situation is somewhat analogous for electric power... In a small car the saving per mile is lower, and so it takes longer to recoup all the fixed costs in a conversion.


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## redshadowz (Dec 8, 2012)

TigerNut said:


> Parasitic losses and parasitic costs both favor the larger conversions. The cost per kW of drive capability, both in the motor and the controller, goes down pretty steeply within the same classes of components; and you need a charger for small and large conversions alike.
> 
> So far as range is concerned, a few mileage mods can push a larger ice car from, say, 20 to 25 miles per gallon. To drive 100 miles you'd need four gallons instead of five, saving one gallon. A 40 mpg car uses 2.5 gallons of gas to go 100 miles; saving one gallon per 100 miles would require you to improve its mileage to 66 mpg... Much more difficult.
> 
> The situation is somewhat analogous for electric power... In a small car the saving per mile is lower, and so it takes longer to recoup all the fixed costs in a conversion.


Well, you are part correct and part incorrect.

The conversion costs of a small car and a large car will be similar for everything other than the batteries.


It should take twice as much power to push a 20 mpg car than a 40 mpg... To increase the 20 mpg to 25 mpg, would be to increase its mpg's by 25%. And to do that, you would need to reduce its air drag and weight by 25%(or some relative factor of each). If you reduced the 40 mpg cars' air drag and weight by 25%, you should also increase its mpg's by 25%(from 40-50).

If it took 200 watt hours to push a 40 mpg car one mile. It should take 400 watt hours to push a 20 mpg car one mile.

If you increased the mpg's of a 20 mpg car to 25, and it took 400 watt hours to go one mile before, then it should only take 300 watt hours now at 25 mpg. If you increased the mpg's of a 40 mpg car to 50 mpg, and it took 200 watt hours to go one mile before, then it should take 150 watt hours now at 50 mpg.


The only benefits a large vehicle could have, is from the power consumption of "accessories". Basically, lights, heat, air conditioning, controller, etc. And from the price being about the same for the "other hardware".

The problem on a large vehicle is that, the weight increase of more batteries would probably offset any benefits from savings from accessories.

This is basically why manufacturers tend to create small cars for conversions. The small, lighter, and more aerodynamic the better(while still being attractive enough for people to buy).


If there were savings from larger cars, it would be because the motors and controllers for larger cars cost basically the same as for smaller cars. So the overall savings per mile if it was proportional, would tend to eat away at the cost of the conversion more quickly.

Basically, if it cost $3k to convert a car to electric that got 20 mpg's, it would still probably cost $3k to convert a car to electric that got 40 mpg's. But since you would be basically burning through more fuel more quickly in the 20 mpg car. If you saved the same amount per mile relative to fuel cost, then you would pay the conversion cost off twice as fast in a larger car. But if the conversion cost was twice as much for a car that got half the mpg's, then there would be no difference.


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## Ziggythewiz (May 16, 2010)

redshadowz said:


> A 35 mpg car at $3.20


Most cars don't get 35 mpg; the average gas price last year was $3.50 and that's just for the cheap stuff which many people don't use.

What world do you live in where you think gas would average $3.20 for the next 8-10 years???



redshadowz said:


> After 100,000 miles, that would be $1610


More like $25-30,000 for me.



redshadowz said:


> The break even point on the battery pack at 3000 charges would be 6.37 cents a mile, or about 53 cents a watt hour for a lifepo4 battery pack.


I paid < $0.38 for mine.



redshadowz said:


> And I would say that 90% of EV conversions never even see the 100,000 mile mark.


99% of EV conversions haven't been around long enough to see 100,000 miles. Most of us also believe in conservation and don't drive for hours a day. 



redshadowz said:


> Basically, it seems to me that 99% of EV conversions, are really people throwing money away.


Since you hate EVs so much, why are you here?


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## redshadowz (Dec 8, 2012)

Ziggythewiz said:


> More like $25-30,000 for me.


Well, a car that gets 40 mpg, and drives 15,000 miles a year. Uses 375 gallons of gas a year. At $3.20 a gallon, thats $1200 a year... By 100,000 miles, thats $8000 miles in gas. Even at $4 a gallon, thats $1500 a year, and $10000 at 100,000 miles

To even spend $30,000 in gas for 100,000, even at $4 a gallon, would require 7500 gallons of gas, which would mean 13.3 miles per gallon.


A highly efficiency 40 mpg car might get as low as 250 watt hours per mile. And the electric cost at that rate to go 100,000 miles would be 25,000,000 watt hours, 25,000 kwh, which is about $2,500.

So the most a person could save in 100,000 miles at a very low 250 watt hours, would be between $5,500 and $7,500. I live in Oklahoma btw.

The problem is that, the cost of the conversion just tends to far outweigh the benefits. About the best a person could hope for would be to just break even.



> Since you hate EVs so much, why are you here?


The truth is, I don't hate EV's. I've been basically obsessed with the idea of EV's for many years now. I think that eventually EV's will displace the gas engine for general transportation. What bothers me when it comes to EV's. Is the cost.

In order for EV's to become desirable. They have to become cost-effective. The sort of impracticality of the EV makes it where it basically has to be a second car, not a primary car. Which means the savings have to be considerable. Because a second car requires monthly insurance, and maintenance, etc.

If we think of it like a commuter car in regards to gas cars. Most people only drive commuters if the commuter car gets between 50-100% better gas mileage than the primary car. Basically, if I get 20 mpg in a normal car, I might use a commuter if it gets 30-40 mpg, saving me considerable money in the long-term.


If we apply that logic, then the only way for an electric car to replace even a gas-powered commuter, would be if it increases efficiency by at least 50-100% as well. Especially considering that you have to come up with a huge investment of money, which has to basically earn interest on itself over time. If I can take $10k and invest it and get 10% a year. Then after seven years(100k miles), I could have doubled that $10k to $20k if I earned 10% interest off an investment.

So basically, not only do the mileage savings need to be significant, the out-of-pocket costs also need to be relatively low.

If I say that it would cost $2,500 in electricity to drive 100,000 miles in ~7 years... And it would cost $10,000 in gas to drive 100,000 miles in the same time-frame.... Then the total cost to convert the vehicle plus whatever interest I would have had off the money spent on the investment, need to be less than $7500.... Even if we were to plug relatively modest numbers of 6,000 for conversion costs, then 5% compounded over 7 years. The real cost to convert would be $8442, throw in $2500 in electricity. That would be about $11000, or $1000 more than a comparable ICE car.



So what I'm saying is, the total conversion cost to travel 100,000 miles, would have to have a total cost of about $2500-$5000 after adjusted for investments/inflation of the money over time.

Basically, the upper limit for a conversion would really need to be about $3500-$4000 for a car that can travel 100,000 miles, otherwise only the hippies will convert their cars.


And from the factory, the cost basis can be no more than about $5500 difference between an EV and a comparable ICE vehicle. Otherwise only the hippies will buy electric.



So I guess my question then becomes. Is it possible to convert a car that uses 250 watt hours per mile or less, that can travel up to 100,000 miles. In which the total cost of conversion plus batteries to travel that distance would cost less than $3500.

To achieve that with lifepo4, it seems like you would probably spend about $1k in motor+controller/throttle+shaft adapter+frames/battery boxes+dc to dc converter+battery management system of some sort+wiring, etc. Which to get all of those things for $1k would be hard to do, and would require you to do all of the real work yourself. And that would live at most about $2500 for a 12kwh pack. 

Basically, to really be practical, the battery cost for lifepo4 would need to be about 20 cents a watt hour. And it seems like the minimum cost right now is about 40 cents a watt hour.

So the question then is, will the cost of lifepo4 drop to 20 cents in the future?


The problem with lead-acid batteries, is I really have no idea what the real life-cycle is of a lead-acid battery at 80% DoD... I hear numbers everywhere from 300 cycles to 800 cycles... A more realistic number might be 500... If that is the case, to get 25,000 kwh from before(250 watt hours/mile, going 100,000 miles). A 115 amp hour 12v battery drained to 20% 500 times would produce 552 kwh. So it would require ~45 batteries to reach 100,000 miles. So the question is, can you buy that many batteries for $2500? Would mean that batteries would have to cost at most $55 a piece(or the conversion cost would need to cost less than $1000 for everything but the batteries.


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## Mike (Jan 4, 2009)

Ziggythewiz said:


> Most cars don't get 35 mpg; the average gas price last year was $3.50 and that's just for the cheap stuff which many people don't use.


Not 100% correct, I have an SKODA Octavia FSI which easily can do 50 MPG at 110 km/h flat land - slight downhill - in summer without A/C - 42 MPG various speeds and A/C- 34 MPG most uphill - and if I go up hill and drive very agresive (which I always tend to do) I get 31 MPG, Now it is True that I am in Europe, and the car have an relative small engine, it is 1,6 l gasoline engine with direct fuel injection. But the Gas prices here are a bit different than in US (kind of double, and some - ~ 1,46 $/l = ~ 5.57 $ gal If I am not wrong, and the price varies - usually upwards) It is true that most cars here are diesel and have an better MPG than gasoline ones.


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## redshadowz (Dec 8, 2012)

Ok, I'm trying to compile this all into a basic formula...



(current price of gallon of gas * 100 / current mpg + price of oil change * 100 / number of miles between oil change) - (((cost of battery *1.25 / (voltage * amp hours)) * (3000 / number of recharges at 80% DoD) * 100 / (3000 / expected watt hour per mile)) + (expected watt hour per mile / 100 * 1.11)

Example...

(4 * 100 / 40 + 30 * 100 / 3000) - (((80 * 1.25 / (12 * 115)) * (3000 / 500) * 100 / (3000 / 240)) + (240 / 100 * 1.11))

Solves as 4.857739130434782608695652173913

If your number is positive, the number represents the savings per mile by cents. If negative, shows the losses per mile in cents.


To find out if your conversion was actually useful after 100,000 miles... you would take the number from above then put it into this formula....

(number from above * 1000) - cost of conversion including batteries * ((1 + ((inflation + yearly investment return after inflation percentage) / 100) / 2) ^ years to reach 100,000 miles) + total cost of batteries

example...

(4.857739130434782608695652173913 * 1000) - 6000 * ((1 +((3 + 7) / 100) / 2) ^ 6) + 5000

Simplifed.. 4857.739130434782608695652173913 - 6000 * 1.340095640625 + 5000

Solves as 1817.165286684782608695652173913

Which means, in 100,000 miles, I would have saved ~$1817 based on my example(about 72 cents a gallon).


Just for reference, my example was... $4 a gallon gas, 40 mpg car, $30 oil change every 3000 miles, expected 240 watt hours per mile, $80 battery, 12 volts, 115 amp hours, 500 recharges, $1000 cost of conversion not including batteries, $5000 for batteries, 3% inflation, 7% return on investment after inflation, 6 years.


The formula isn't complete, because it doesn't predict watt hours per mile. Nor does it give a relatively accurate measure of the battery requirements. Nor does it accurately judge exponential growth of investments.. Though it would be pretty easy to figure out, just don't feel like doing the math ATM.


I should turn it into a web template of some sort.


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## redshadowz (Dec 8, 2012)

Anyway, the problem is that if you plug what I would consider "my numbers" into the formula, it would go....


(2.40 * 100 / 40 + 15 * 100 / 5000) - (((128 * 1.25 / (3.2 * 100)) * (3000 / 3000) * (4 / 3) * 100 / (3000 / 300)) + (300 / 100 * 1.11 + 15 * 100 / 5000))

The input is a 40 cents per watt hour 3000 charge lifepo4.... But in my example, gas is $3 a gallon in a 40 mpg car, and I change my oil myself every 5000 miles. The actual cost per mile based on the example, is only 7.8 cents for me(was 11 cents a gallon with $30 oil change every 3000 miles, and $4 gas in a 40 mpg car).

The 40 cents per watt is increased by 20% because you aren't supposed to drain a battery below 80%. So that pushes its cost to 50 cents a watt hour. One watt hour at 3000 charges is 3kwh. With 300 watt hours per mile, one watt hour of battery would travel 10 miles. So you take the 50 cents per watt hour and divide by the range(10 miles) to make 5 cents per mile for battery. Then we add electricity cost, which is 300 watt hours(.3kwh), so 3 cents per mile but you lose about 10% efficiency during recharge. So its 3.33 cents per mile for electricity costs. Total cost would be 8.33 cents per mile.

But since the 8.33 cents per mile battery cost is greater than the 7.8 cents per mile gas price, you lose .53 cents per mile($530 after 100,000 miles)


Throw in the conversion cost, and interest and inflation on the costs of conversion. You could be down thousands of dollars after 100,000 miles.


But, tweaking the costs a bit could go a long ways.. If gas was $5 a gallon for instance, it would cost 13.5 cents per mile in a 40mpg car. At 10 cents per kwh, even at 40 cents per watt hour for lifepo4. It would be 8.33 cents per mile, which after 100,000 miles the difference would be $5170. Which could easily pay for the conversion.

I'm sort of a special-case in all of this, because I live in an area where gas is incredibly cheap generally(Oklahoma). It isn't unrealistic to get 50 mpg in a lightly modified high mileage stock car. Under such characteristics, my cost per mile would only be about 5 cents.

Which really, to be cost competitive, the entire cost of conversion other than the batteries couldn't exceed $1,000. And the cost per battery mile + electricity per mile, couldn't exceed 4 cents.

Even at an incredible efficiency rate of 250 watt hours per mile, it would cost 2.5 cents per mile in electric. Which means the battery cost per mile could not be greater than 1.5 cents for me.


So the question then becomes, what would the specs of a battery need to be to reduce battery cost to only 1.5 cents per mile for? Which in my view, EV's can never be cost competitive until the battery cost per mile falls to at least somewhere around 2 cents per mile at 250 watt hours per mile. Because gas prices are going to go up and down. If people switched from gas tomorrow, the price of oil would just drop until EV's were impractical again. So unless you can reduce battery prices significantly. You are really gambling heavily with your money, and EV's will continue to need subsidies.


So how close are we to 1.5 cents per mile for 250 watt hours? Well, if lifepo4's cost 25 cents a watt hour, that would be roughly 2 cents a mile in battery at 250 watt hours/mile. For the conversion to be cost effective for me, would require about 18 cents per watt hour of lifepo4's.

So the question is, what is the theoretical minimum cost for lifepo4's? Will they ever see 18 cents per watt hour? And what kind of alternative battery technology might be on the horizon that could fix the battery cost problem?


I gave up on EESTOR and all other "ultracapacitors" a while ago. Batteries really disappoint me.


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## ricklearned (Mar 3, 2012)

redshadowz said:


> Anyway, the problem is that if you plug what I would consider "my numbers" into the formula, it would go....
> 
> ...........
> ................ Batteries really disappoint me.


Sometimes the human condition disappoints me. Someone once told me, "Don't let perfect be the enemy of good."

Yes, batteries have a finite life just like us humans. I am 68 years old, I have 20 Kwhr of Lithiums that are less than a year old. If I take really good care of them I might get 8 to 10 years out of them. By then I will be 78 years old and there will be something even better. Do I care? No. I might not even be able to drive in 10 years. 

Occassionally when I pull away from a stop sign, next to a performance car (read gas guzzler) I put the pedal to the metal and it makes me feel like a teenager again. I have an EV Grin three or four times a day and I think having a smile on your face is priceless. Not to mention the joy of blowing off a $30 to 40k new car with a 40 year old VW, (at least for the first couple of hundred yards). Try putting that into your formula. LOL


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## redshadowz (Dec 8, 2012)

I just want to finish this thing by saying... This website has a clearance of batteries. Not sure why they are on clearance exactly.

http://balqon.com/store.php#!/~/product/category=4218089&id=18005965

That battery is 160 amp hour for $99.. Which puts it about ~19 cents a watt hour. That price places it within my specs. But there are only 6 of them, and I don't really know what the shipping would be.

I would need 30 of them for 96 volts, and that would make a ~15kwh battery pack. Which would give a ~40-50 mile range to 80% DoD.


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## ricklearned (Mar 3, 2012)

Balqon is where I got my batteries and the last group of 90Ahr cells cost me $0.30 per watt hr. Call Steve and see is he will make a deal.


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