# Can anyone add to



## PTCruisin (Nov 19, 2009)

320Wh/mi, 3000 lbs vehicle weight.


----------



## dladd (Jun 1, 2011)

I think you need to qualify any data here with how you obtained the numbers. Is it read off an AH counter multiplied by nominal voltage? a computer that takes instantaneous voltage into account? From the wall before the charger? Too many different ways to get the same number. Or at least a number with the same units.


----------



## Rational (Nov 26, 2011)

Thanks - so now it's 

300
310
320, 3000 lbs.
325
400

Turns out that w-h due to vehicle weight due to rolling resistance is negligible \/

rolling resistance is 0.01 so 
a 1000kg car needs 10 kg to push it	
10	=kg of rolling resistance
1610	=distance in meters
116160	=calc'd ft-lbs
43.75	=calc'd w-h/mile

but weight will affect acceleration.

As to units, etc., that can be sorted out into subcategories of vehicles. That's later. This is for kind of a global overview.

Turns out that doing the stats on five values is not so easy
http://en.wikipedia.org/wiki/Quartile


----------



## dtbaker (Jan 5, 2008)

dladd said:


> I think you need to qualify any data here with how you obtained the numbers. Is it read off an AH counter multiplied by nominal voltage? a computer that takes instantaneous voltage into account? From the wall before the charger? Too many different ways to get the same number. Or at least a number with the same units.



excellent point DLADD.

this number will vary HUGELY depending on vehicle, speed, terrain, driving style, and whether its 'at the wall', or reported by in-car meter like Cycle Analyst, evDisplay, etc. The difference at the wall versus in-car meter varies hugely by battery type (charge curve) and charger loss (charger eff).

in my case:
2020# vehicle w/ LiFepo4 prismatic cells, Elcon 1500 charger

over 1000 mile use I last measured 290watt-hr/mile at the wall w/ kill-a-watt meter

terrain is 'rolling', suburban traffic with 35 mph average speeds and several stops per mile on average. max speeds 55mph, driving style not ecomodding, but limited by anemic Curtis 1221 controller.


----------



## tomofreno (Mar 3, 2009)

> Turns out that w-h due to vehicle weight due to rolling resistance is negligible


 Bob Brant gives rolling resistance as 0.012*w*(1 + V/100)*cos(phi), where phi varies from 0 to 90 degree incline and w is weight. I found a coeff of 0.008 seems to fit measured results on my car better. Using that the rolling resistance force is equal the drag force at a bit over 45 mph and greater below. This is fairly typical for a sedan.

I agree with dt - kind of a worthless exercise due to all the variability. Better to ask energy/mile for a specific set of conditions.


----------



## Rational (Nov 26, 2011)

Thanks for all the info - I have some thinking to do.

Without including the specs for the Tesla Roadster, here's what Excel says so far

w-h/mile	lbs	w-h/mile-lb
290	.......2200	0.132
300 
310 
320	.......3000	0.107
325 
400 

3/4ths of the vehicles sampled so far do better than 
323.75	w-h/mile


----------



## dtbaker (Jan 5, 2008)

Rational said:


> w-h/mile lbs w-h/mile-lb
> 290 .......2200 0.132


my vehicle weighs 2020, not 2200.... and that is consumption 'at-the-wall' under driving conditions described above. If you are going to gather numbers and present data, I think you need to state conditions so you are sure to compare apples-to-apples. Otherwise, the results are meaningless.


----------



## Rational (Nov 26, 2011)

There's a truck in here, so I guess I can be no more specific than to call this collection, 

vehicle, electric, 4 wheeled 

and these are what the results apply to. Everything else - driving conditions, city/country, one or more passengers, head/tail wind, flat/hilly, the whole bit is mushed in here. 
The more data points, the more 'robust' the quartiles become. With more data I can split out subcategories.

Somehow Excel is able to do quartiles on only three data points.

w-h/mile	lbs	w-h/mile-lb
275	4800	0.057......truck
225 
240 
265 
290	2020	0.144
300 
310 
320	3000	0.107
325 
400 


3/4ths of the vehicles sampled do better than 
317.5	w-h/mile	
and better than	
0.125	w-h/mile-lb


----------



## PhantomPholly (Aug 20, 2008)

Rather than trying to come up with some "rule" about Watt hrs / mile, simply convert based on the chosen vehicle's mpg at a given weight.

We previously established that 8 Kwh is approximately equal to 1 gallon of gas in the same car, and that at today's battery weights after conversion you will probably have "the same vehicle weight" with somewhere between 8 - 24 Kwh worth of batteries, depending on conversion choices of motor, battery tech, controller, etc.


----------



## dtbaker (Jan 5, 2008)

PhantomPholly said:


> Rather than trying to come up with some "rule" about Watt hrs / mile, simply convert based on the chosen vehicle's mpg at a given weight.
> 
> We previously established that 8 Kwh is approximately equal to 1 gallon of gas in the same car, and that at today's battery weights after conversion you will probably have "the same vehicle weight" with somewhere between 8 - 24 Kwh worth of batteries, depending on conversion choices of motor, battery tech, controller, etc.



hooray for not attempting to over analyse.  there are too many variables to calculate range estimators very closely. Using a vehicle's ICE mpg takes a lot of them into account.... aero, driving style, terrain, etc.

going that route, lets pool some numbers for Rational to play with....

my Swift got about 40mpg on gas.
I now have a max range of 50 miles with 12 kWhr (120vx100ah cells) on board.
Charging of course takes more from the wall because of 'losses' in charging and driving. So one multiplier might be used for estimating range, and the other for operational cost of electricity 'from the wall'.

I have never run the pack down past 80% DOD, but have checked many times and I go right around 25 miles at 50% DOD on my average daily driving.


----------



## PhantomPholly (Aug 20, 2008)

dtbaker said:


> hooray for not attempting to over analyse.  there are too many variables to calculate range estimators very closely. Using a vehicle's ICE mpg takes a lot of them into account.... aero, driving style, terrain, etc.
> 
> going that route, lets pool some numbers for Rational to play with....
> 
> ...


8Kwh * 50 / 40 = 10 Kwh approximately used; 10/12 = .833 = ~~80% dead so the "rule of thumb" appears to be holding, at least approximately. Can you confirm whether the pack was 80% DOD or some other value after your 50 miles of driving? I think in the original thread the person who posited 8Kwh actually gave a range of 7.5 - 8.5 depending on efficiency of the whole system.



> Charging of course takes more from the wall because of 'losses' in charging and driving. So one multiplier might be used for estimating range, and the other for operational cost of electricity 'from the wall'.





> I have never run the pack down past 80% DOD, but have checked many times and I go right around 25 miles at 50% DOD on my average daily driving.


Ack, that means you are really using closer to 10Kwh = 1 gallon.

Would really be informative if you would simply drive 40 miles and tell us what % DOD you end up with...


----------



## dtbaker (Jan 5, 2008)

PhantomPholly said:


> Ack, that means you are really using closer to 10Kwh = 1 gallon.



no, thats not what I wrote, quite. Close though.

...I am trying to say that my Swift, which got 40 mpg on gas, 
now gets 25 miles per 6kWhr, or 4.2 miles per kWhr expended by the pack as measured by my CycleAnalyst.

the second point I was trying to make is that this number would be useful in developing a range multiplier, but NOT the total energy it requires from the wall to calculate operational cost. It would require measuring the kWhr 'at the wall' it takes to fill the pack back up to account for the energy lost by the charger during charge.

the 6kWhr is 50%DOD in my pack which happens to be 120v nominal (38 x 100ah cells).

so..... yeah, in MY car it takes about 9.52 kWhr to get as far as 1 gallon of gas using prismatic Li cells (Thundersky).

on 800# of lead it took 96v x 185ah (20hr rating) = 38 miles at best when new, or only 2.14 miles per rated kWhr because of peukarts.....


----------



## Rational (Nov 26, 2011)

dtbaker said:


> Swift
> I now have a max range of 50 miles with 12 kWhr (120vx100ah cells)


How much does the Swift now weigh? 

You wouldn't happen to have the drag coefficient and cross sectional area, would you? Drive wheel radius? Motor torque/speed curve? 
Now we're talking! 

There is more than one way to skin a cat. . .


----------



## dtbaker (Jan 5, 2008)

Rational said:


> How much does the Swift now weigh?


I already told you, twice. 2020#




Rational said:


> You wouldn't happen to have the drag coefficient and cross sectional area, would you? Drive wheel radius? Motor torque/speed curve?
> Now we're talking!
> 
> There is more than one way to skin a cat. . .


I really dont have these numbers at hand... nor do I intend to spend time looking them up. Perhaps wikipedia will have all the car specs you want. oh, but the drag coeff is probably all off because of the hood scoop.

ohhh, and I may see a vast improvement in the near future. Last weekend I added a partial bellypan. Mostly to keep the snow and mud out, but it MIGHT have some aero effect.


----------



## Rational (Nov 26, 2011)

It's been a real pleasure talking with you 

four wheeled electric vehicles 

Column key 
A	w-h/mile 
B	weight in lbs 
C	w-h/mile per pound of vehicle weight 
D	hp 
E	lb-ft torque 

A	B	C	D	E	notes
217	2723	0.080	248	200	tesla roadster
275	4800	0.057 truck
225 
340	3354	0.101	110	210	Nissan Leaf
240 
265 
290	2020	0.144 dtbaker
240 swift, dtbaker
300 
310 
320	3000	0.107 ptcruisin
325 
161	1250	0.129 
400 


3/4ths of the vehicles sampled did better than 
317.5	w-h/mile 
and better than 
0.123	w-h/mile-lb 

half the vehicles weighed between
3266
and
2196
pounds


----------



## ElectriCar (Jun 15, 2008)

Watts from the utility or from the pack? The difference in the two is about 12% in my 91 S10 truck, an aerodynamic brick.

But from the wall I'm averaging about right now 400wh/mile using heat and lights some. Also pulling a trailer some. With no heat or lights it's closer to maybe 385wh/m. If I still drove it easy like I did with a lead pack I'd be closer to 350wh/mile.

The truck hasn't been weighed since the lithium conversion but I estimated it to come in around 3200-3300lbs. I have lrr tires also.

Max torque is around 270ft lbs with my modified controller. Considering pack sag, I think peak hp is about 210.


----------



## dtbaker (Jan 5, 2008)

Rational said:


> It's been a real pleasure talking with you



i just think you are wasting your time, and ours, attempting to pull statistics out of unqualified data. for instance, one huge factor you aren't considering is whether the vehicle is DC or AC.

data points way outside the others, like the 4800 pound truck, you ought to take a much closer look at the data to understand if you are comparing apples to apples.

....and you have never clarified whether you want consumption numbers from in-vehicle ahr meters to concentrate on vehicle range/kWhr, or operational energy added 'at the wall' including charger losses as measured by kill-a-watt meters or similar.

A great suggestion was made a couple posts ago to correlate the original ICE mpg to post-conversion kWhr/mile.... which would take into account a lot of the variables in aero, driving terrain, driving style, etc. Leaving only the AC versus DC motor qualification requiring two data tables; I don't think it has much use if you insist in throwing everything into one formula.


----------



## Rational (Nov 26, 2011)

dtbaker said:


> A great suggestion was made a couple posts ago to correlate the original ICE mpg to post-conversion kWhr/mile.... which would take into account a lot of the variables in aero, driving terrain, driving style, etc. Leaving only the AC versus DC motor qualification requiring two data tables


Good idea! Do it!


----------



## dtbaker (Jan 5, 2008)

Rational said:


> Good idea! Do it!



ok.....

after much gnashing of numbers, observation of reported builds, and taking sunspots into account, my hypothesis is that a pretty damn close estimate of consumption by a DC-powered EV will be that you will get:

Xmiles per kWhr = .1(ICE mpg) for any given vehicle

and for AC the modifier will increase the range by 10% to give:

Xmiles per kWhr = .11(ICE mpg) for any given vehicle

done!


----------



## Rational (Nov 26, 2011)

Good
http://en.wikipedia.org/wiki/Point_estimation
Would you care to give an
http://en.wikipedia.org/wiki/Interval_estimation
?
How 'bout one of these
http://en.wikipedia.org/wiki/Confidence_interval
?

How 'bout either leaving me alone or banning me?


----------

