# What is the cost per mile of batteries



## rfengineers (Jun 2, 2008)

In my Sunfire, if I take reasonably good care of my FLA batteries the cost of operating the EV is about 13-cents per mile for the battery and 6-cents per mile for the electricity.

If I DON'T take care of the batteries then the operating costs go way up.


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## Ziggythewiz (May 16, 2010)

I expect mine to be similar, but under $0.02/mile for the electricity, so around 15 cents/mile vs 25+ in my gasser.


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## rfengineers (Jun 2, 2008)

Most people with FLA batteries are getting 250 to 500 WattHours/Mile (measured at the wall outlet). The lower numbers are for the very light, relatively slow vehicles. My car is closer to the 1/2 kWHr/mile figure and I pay about 13-cents per kilowatt hour.

If you are operating a vehicle that can carry more than one, or two very small, person(s) at 2-cents per mile then, congratulations!! Please share your secrets with the rest of us.


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## Ziggythewiz (May 16, 2010)

VW beetle, usually carries one, but has done 4. WH/M around 225 from plug, city streets only avg 40 mph. 

$0.09/WH helps, the only other thing I have different from most is no DC-DC. I don't know how much those things use, but it must be higher than the 20 wh I used to charge my ACC batt with.


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## gojo (Feb 1, 2011)

I like to think the savings is in maintaining the EV. With quality components there is little to go wrong with the car. I only need to add water to my batteries, and put air in the tires occassionally. 

I also like not supporting the oil companies, and not being as responsible for the military involvment in the Mideast as the average person.


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## Ziggythewiz (May 16, 2010)

Good points. Figure at least 2 oil changes per year, antifreeze, emissions inspection ($25 for me), any engine tuneups (or that $600 timing belt that disintegrated on the hwy).

I especially like knowing how much it will cost to drive to work next month. $10. The next month? $10. Next year? $10...or less as electricity (here) has gone down the last 5 years at least.


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## otmezger (Jun 6, 2011)

One of the main factors that will bring the costs to the roof is having a too big battery. If your daily driving distances are short and you drive smooth, having a small battery will increase dramatically the cost effectiveness.

For knowing the size of the battery, use our electric car simulator for iPhone. Just drive with your normal car, and read the results after a few drives. This is my part, for the rest of the story, there might be people in this forum that will help you further. 


Thank you,
Olmo
CEO
The Green & Energy Consulting Group


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## dtbaker (Jan 5, 2008)

jim15800 said:


> I have just begun to consider an EV. I am concerned as to whether the cost of batteries may make it to expensive to be practical. How often will lead acid batteries need to be replaced? Is it a factor of time and usage or just usage and the same question for lithium Ion batteries? Will the batteries have to be replaced so often that when you factor the battery cost it negates the fuel advantage? Please provide me with any insight you are willing to provide. Thank you in advance for your time.


My best calcs indicate the operational cost of a lead-acid build will end up costing about the same as gas if gas is $2.75-3.00/gal. over 10 years (3 or 4 sets of batteries) A LiFePO4 build is way cheaper because the batteries will probably last the whole 10 years.... Read thru my calcs on my site (link below), and feel free to comment.....

with my car I am lucky enough to have recorded the mpg on gas, on lead-acid, and now as Li. The Li is way better on several counts: lighter weight is more efficient, no 'gassing' in charge cycle is way more efficient, and (hopefully) 4x-5x the life cycles of lead. So depending on whether you amortize the cost of the batteries as a consumable over the ten year expected life affects whether you consider it a capital cost or operational cost.... i.e. is the whole car dead after ten years (as is the average ICE engine needing major overhaul) for compare? Either way the Li is actually les expensive than gas at today's prices.


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## rmay635703 (Oct 23, 2008)

rfengineers said:


> If you are operating a vehicle that can carry more than one, or two very small, person(s) at 2-cents per mile then, congratulations!! Please share your secrets with the rest of us.


My fathers miles ZX40 comes very close, it seats 4 easily and chugs along at about 144wthr per mile at the battery (only 65amps at 27mph and 50 amps at 30mph when we get there, 36mph takes about 100amps but we don't do that much, way too fast).
At the wall we use between 170wthr to 200wthr per mile, my greensaver gel batteries seem to have very little charging loss, especially if I don't take them over 90% charge. (PS we pay roughly 11 cents per Kwthr very close indeed to your 2 cents)
Of coarse the vehicle only travels 25-35mph most of the time and is awefull slow past 25mph. Actually its awefull slow all the time (48v + Curtis 1204 and a 6 3/4" motor with occasional field reduction).
Cheers
Ryan


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## Ziggythewiz (May 16, 2010)

dtbaker said:


> My best calcs indicate the operational cost of a lead-acid build will end up costing about the same as gas if gas is $2.75-3.00/gal. over 10 years (3 or 4 sets of batteries) A LiFePO4 build is way cheaper because the batteries will probably last the whole 10 years.... Read thru my calcs on my site (link below), and feel free to comment.....


An important variable to consider is opportunity cost. dtbaker's calculations are based on his car that would get 30 mpg, so his break even point for lead is $3.90/gal, while for LiFePO4 it would be $1.80/gal (over 10 years). For him only lithium can payoff at current prices.

My opportunity costs are based on my 16 mpg minivan that reguires premium gas (about $0.12-$0.15 more than regular) so my break even point for lead is ~$2.26 and for lithium would be around $1. Gas will never again hit either of those prices, so I can expect a ROI no matter what batteries I use, though it would come faster if I can save up for the lithium investment.

This is of course just considering the operating costs of batteries and electricity vs gas, no maintenance or other savings as discussed above considered.


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## jim15800 (Jun 5, 2011)

Question for Dan. What is the lifespan for lithuim batteries? Should the batteries last more than 10 years or is 10 years the limit. 


Also I would like to thank everyone who has replied to my question.


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## valerun (Nov 12, 2010)

jim15800 said:


> Question for Dan. What is the lifespan for lithuim batteries? Should the batteries last more than 10 years or is 10 years the limit.
> 
> 
> Also I would like to thank everyone who has replied to my question.


as far as I understand, the cycle life rating is before 20% capacity loss. Correct me if I'm off.


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## tomofreno (Mar 3, 2009)

> Question for Dan. What is the lifespan for lithuim batteries? Should the batteries last more than 10 years or is 10 years the limit.


 We would all like to know the answer to this question. The spec for CALB cells is 3000 cycles at 70% depth of discharge (DoD), and I believe the Thundersky spec is 5000 cycles. If they meet this spec under conditions of ev use, that would be 10 years or more for most people. No one has been using them more than 3 or 4 years I think, most of us less than 2.


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## dtbaker (Jan 5, 2008)

Ziggythewiz said:


> An important variable to consider is opportunity cost. dtbaker's calculations are based on his car that would get 30 mpg, so his break even point for lead is $3.90/gal, while for LiFePO4 it would be $1.80/gal (over 10 years). For him only lithium can payoff at current prices.


actually my car and calcs are based on 40 mpg on gas, not 30... I am going to revise my numbers a little as I now have good figures for average electric use 'at the plug'. Interesting to note that even though my little Swift shows consumption of less than 200 Whr per mile on the Cycle Analyst, the average 'at the plug' consistently comes in at almost 300 whr per mile with charger and system motor/controller losses. Still, far better than lead-acid which was very close to 500whr per mile for same car same routes because of higher loss in charge cycle and hauling more weight.

The other factor that I think I need to throw in to be 'fair' is that if you really want to amortize operational costs, you should include probably $1000 for the gas engine as it would need at least a belt or water pump or some major rebuilt over 10 years.

so.... lead-acid is maybe cheaper than gas, maybe, but Lithium is likely to be WAY better than either over a 10 year life.


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## dtbaker (Jan 5, 2008)

tomofreno said:


> We would all like to know the answer to this question. ... No one has been using them more than 3 or 4 years I think, most of us less than 2.


yup, we are all guessing at this point. also guessing how temp control, upper charge limit, and average DOD might affect total life miles too. My average use is pretty gentle at less than 50% DOD,and I can often recharge mid-day. I also have little 'extended high-amp' pulls in normal urban traffic, so the internal temp of batteries never really rises at mostly 1C-2C with 'rests'.

I am hoping I'll get at least 75,000 miles, and maybe 100,000

I did add a couple remote thermometers in my battery boxes, and the only time I have seen the temp rise 20 degrees above ambient was when I took an unusual trip 15 miles out on the highway, and had a steady 20 minute pull slightly uphill at 2C-2.5C It was about 75 degF out, and the battery box (sealed and insulated with sensor taped to bus bar) got up to 95 deg F


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## valerun (Nov 12, 2010)

I have set my charger to terminate at CV of 3.5V to leave 2-3% of capacity at the top untapped. From what I read, this should substantially increase battery life. There is a reason why both Volt and Leaf limits top SOC in the 'battery longevity' mode.


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## jim15800 (Jun 5, 2011)

Where is an economical source for lithuim batteries?


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## dtbaker (Jan 5, 2008)

the supply line for thundersky/winston seems 'sketchy' at this time.... but good reports going direct to http://www.calibpower.com/Product.aspx for CALB in the US.


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## gojo (Feb 1, 2011)

tomofreno said:


> We would all like to know the answer to this question. The spec for CALB cells is 3000 cycles at 70% depth of discharge (DoD), and I believe the Thundersky spec is 5000 cycles. If they meet this spec under conditions of ev use, that would be 10 years or more for most people. No one has been using them more than 3 or 4 years I think, most of us less than 2.


I have been using LiFePo4's in ebikes, and all I got was 3 years on two different packs, so I am skeptical of 10 years. I now keep my pack refrigerated when I not using it in hopes of preserving it a little longer.


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## jim15800 (Jun 5, 2011)

gojo said:


> I have been using LiFePo4's in ebikes, and all I got was 3 years on two different packs, so I am skeptical of 10 years. I now keep my pack refrigerated when I not using it in hopes of preserving it a little longer.


Did you keep the batteries charged in the ebikes or did you let them discharge?


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## tomofreno (Mar 3, 2009)

> I have been using LiFePo4's in ebikes, and all I got was 3 years on two different packs, so I am skeptical of 10 years. I now keep my pack refrigerated when I not using it in hopes of preserving it a little longer.


 This is not very useful information without details of how the cells were used. Were they ever overcharged or overdischarged? What discharge rate did you typically use as a fraction or multiple of C, the cell capacity? Are these the large volume prismatic cells used in cars? What cells are they and what is their spec for use and cycle life?


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## dtbaker (Jan 5, 2008)

gojo said:


> I have been using LiFePo4's in ebikes, and all I got was 3 years on two different packs, so I am skeptical of 10 years. I now keep my pack refrigerated when I not using it in hopes of preserving it a little longer.



you were using the large format prismatic cells (Thundersky/Winston or CALB) on an eBike? 

what makes you think refrigeration helps? That seems like it would be the best way to reduce range! They say quite clearly NOT to charge if temp is below 32 deg f. Being below 70 deg F reduces range, and if you consistantly over-discharge that would explain the ealier demise of your cells.


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## jimy_f_84 (Jun 3, 2011)

gojo said:


> I like to think the savings is in maintaining the EV. With quality components there is little to go wrong with the car. I only need to add water to my batteries, and put air in the tires occassionally.
> 
> I also like not supporting the oil companies, and not being as responsible for the military involvment in the Mideast as the average person.


Props for that!! my car averages 27 MPG, so about $0.14 a mile, so by going EV with FLA i will most likely spend same or more, but i hear ya man, and it is tempting to not use oil anymore, let electricity carry out their wars!


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