# [EVDL] Lithium vs. gasoline



## EVDL List (Jul 27, 2007)

> Roger Daisley wrote:
> 
> > I'm developing an electric riding lawn mower conversion for possible
> > resale.
> ...


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## EVDL List (Jul 27, 2007)

> On 30 Sep 2011 at 11:11, Roger Daisley wrote:
> 
> > ... four Costco 12 v "deep cycle" marine batteries ... the tractor will
> > run well for ~15-minutes.
> ...


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## EVDL List (Jul 27, 2007)

Previously on the EVDL, I've been told that you can consider 9kWh of lithium
cells to be about the net equivalent of 1 gallon of gasoline burned in a
car. So, if you can get 30 MPG from your car, you can get about 30 miles
range on 9kWh of lithium cells. My conversion tends to back this up. I
have about 15 kWh and consider my effective range about 45-50 miles. The
person making the original claim had looked through the EVDL and based this
conclusion on the overall average of several conversions running lithium. I
have found it an extremely useful rule of thumb.

So, I would say you need about 9-10 kWh of cells if you really need the
equivalent of 1 gallon of gas in lithium cells. Still thousands of dollars.

As David pointed out, it would be a lot cheaper to make the system more
efficient first.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Roger Stockton
> Sent: Friday, September 30, 2011 12:39 PM
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] Lithium vs. gasoline
> 


> > Roger Daisley wrote:
> >
> > > I'm developing an electric riding lawn mower conversion for possible
> > > resale.
> ...


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## EVDL List (Jul 27, 2007)

> Mike Nickerson wrote:
> 
> > Previously on the EVDL, I've been told that you can consider 9kWh of
> > lithium
> ...


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## EVDL List (Jul 27, 2007)

I'd go with 14 or 16 (even number for neater install) of 160Ah TS (or 
whatever they are called these days) and not worry about the rating. 
Keeping the currant draw at 1C I my experience will see you get at 
least two thousand cycles - longer than the machine will last, I 
suspect.

The V belt drive is not wildly inefficient - typically around 95%, but 
if you want to improve it to 98% you might consider replacing the v- 
belt drive with a toothed one. I don't think you will get much better 
with anything else - and then there's the extra cost of re-engineering.

Unfortunately, I can't see you getting your money back let alone 
making a profit - unless it's going to be used somewhere that has an 
issue with noise - or burning petrol fumes - where you might have an 
advantage with an electric drive machine.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk




> Roger Daisley wrote:
> 
> > I'm developing an electric riding lawn mower conversion for possible
> > resale.
> ...


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## EVDL List (Jul 27, 2007)

This rule of thumb has actually been on the EVDL a few times:

It wasn't exactly the posting I was looking for, but this posting has the
same information. Look at the first response from Jack Rickard in the
thread:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/How-many-watt-h
ours-mile-would-a-Hummer-take-td452319.html. Jack mentions the nominal
value of 8800 Wh per gallon of gasoline, then mentions that he derates that
to 8000 Wh/gal.

Another post from Jack with similar information:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/EV-Range-questi
on-td450528.html#a450530

The post I was originally thinking of was:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/Re-Why-I-love-S
ep-Ex-WAS-Re-generative-Braking-td448737.html#a732263. Tom Alvary posted
the answer in response to a question I asked about converting MPG to
wh/mile.

It looks like I mis-remembered the number. I remembered 9 kWh / gallon
instead of 8 kWh / gallon. Oops.

Actually, this formula would work very well for John's F250. That is
probably an 8-10 MPG vehicle with the original gas engine. That means it
would get 8-10 miles range on a lithium pack with 8-9 kWh capacity. That's
the beauty of the rule of thumb.

I was keying off the original poster's belief that running for an hour would
take a gallon of gasoline.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Roger Stockton
> Sent: Friday, September 30, 2011 7:06 PM
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] Lithium vs. gasoline
> 


> > Mike Nickerson wrote:
> >
> > > Previously on the EVDL, I've been told that you can consider 9kWh of
> > > lithium cells to be about the net equivalent of 1 gallon of gasoline
> ...


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## EVDL List (Jul 27, 2007)

> Mike Nickerson wrote:
> 
> > This rule of thumb has actually been on the EVDL a few times:
> 
> ...


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## EVDL List (Jul 27, 2007)

Maybe I should have searched the archives but I recall 700-1000lbs of
lead acid batteries giving the range equivalent to 1 gallon of
gasoline which matches much more closely with John's 3000lb of lead
acid.

On Sat, Oct 1, 2011 at 5:31 PM, Roger Stockton <[email protected]> wrot=
e:
> John has about 40-43kWh of usable energy in his 3000lb lead acid pack, ye=
t says he gets an absolute max of 30mi range. If the vehicle got 8mpg in=
ICE trim, then the 8kWh of lithium per gallon of gas rule would have had J=
ohn installing only 30kWh and getting about 22mi range instead of the expec=
ted 30mi. (It isn't just the lithium rule that fails here; the lead-acid=
rule of 500lbs =3D 1 gallon would have John expecting that just 1500lbs of=
lead would give his 30mi range, yet the reality is that he needs twice tha=
t amount because his situation is so far away from the vehicles from which =
the rule was derived.)
>

-- =

David D. Nelson
http://evalbum.com/1328

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## EVDL List (Jul 27, 2007)

David Nelson wrote:

> Maybe I should have searched the archives but I recall 700-1000lbs of
> lead acid batteries giving the range equivalent to 1 gallon of
> gasoline which matches much more closely with John's 3000lb of lead
> acid.

Took me a bit of digging in my archives to find it, but 500lbs it is:

>


> Bill Dube wrote:
> >
> > > Figure that 500 lbs of lead is about 1 gallon of gasoline.
> > >
> ...


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## EVDL List (Jul 27, 2007)

Wow, I wonder where I got the other figure? That definitely
underscores your point about rules of thumb. Maybe the half the 20hr
capacity rate is a better rule of thumb and a bit more conservative.

On Sun, Oct 2, 2011 at 11:27 AM, Roger Stockton <[email protected]> wro=
te:
> David Nelson wrote:
>
>> Maybe I should have searched the archives but I recall 700-1000lbs of
>> lead acid batteries giving the range equivalent to 1 gallon of
>> gasoline which matches much more closely with John's 3000lb of lead
>> acid.
>
> Took me a bit of digging in my archives to find it, but 500lbs it is:
>
>>


> Bill Dube wrote:
> >>
> >> > Figure that 500 lbs of lead is about 1 gallon of gasoline.
> >> >
> ...


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## EVDL List (Jul 27, 2007)

The DOE uses 33.7 kWh/gal of gasoline. I think Jack and others on EVDL are
referring to the actual energy required accounting for the difference in
efficiency between an ice and ev - roughly 20% versus 80%. For example, my
car with its original ice would go about 35 miles on a gallon of gas at 55
mph. The converted car uses about 7.5kWh to go 35 miles at 55 mph (about
215Wh/mile). Using the DOE figure, that is about 0.22 gallons of gas
equivalent, or a bit over 4 times the efficiency of the ice.

--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Lithium-vs-gasoline-tp3860658p3867503.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

> On 3 Oct 2011 at 12:41, Lee Hart wrote:
> 
> > The conversion is about mpg x 10 =
> > wh/mile. Example: 30 mpg = 300 watthour/mile.
> ...


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## EVDL List (Jul 27, 2007)

>
> Thank you, Lee for this information. I have been searching without success
> in the archives for this very formula to understand how to estimate the kwh
> for my new pack.
>
Michael B

>
> Every battery has a published voltage and amphour rating. Volts x
> amphours (preferably at the 1-hour rate) is watthours per battery.
> Example: T-145 golf cart battery is 6v x 150ah (1hr rate) = 900 watthours.
>
> Then the range per battery is (900wh) / (300wh/mile) = 3 miles per battery.
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
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## EVDL List (Jul 27, 2007)

'Tis the time for typos to keep us humble 



> WILLIAM DENNIS Owner <[email protected]> wrote:
> > Grrr! 9,000 Wh, I meant.
> >
> > Bill
> ...


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## EVDL List (Jul 27, 2007)

Another rule of thumb in the lead world is that if you can get 1/3 of the 
vehicle weight in batteries, the practical range will be around 35-40 miles. 
If you can achieve 1/2 its total weight in lead, a usable range of 55-60 
miles is quite possible.

Of course this varies with the type of vehice, driving style, geographics, 
weather, and so on. A boxy vehicle driven fast so that aerodynamics come 
into play will have much less range, for example. So will one with dragging 
brakes, sticky tires, or carelessly aligned wheels. Cold temperatures 
always reduce range. So will lots of stops and starts, especially with 
rough acceleration.

OTOH, a very aerodynamic vehicle driven moderately in a warm climate is apt 
to do better than this would predict. Regenerative braking (recuperation) 
will also add a bit to the range.

David Roden - Akron, Ohio, USA
EVDL Administrator

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