# How much Battery needed



## Semper Vivus (Apr 13, 2011)

Hello,

to answe your question, more information is needed.
At what speed shall that 300km be driven?
Are that 5kw (continuous I guess) only motor data or the power you need at your desired speed? If it is only motor data, how aerodynamic or heavy is your vehicle?

Regards,
Tom


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## pdove (Jan 9, 2012)

Take your vehicle weight and divide by ten.

3100 lbs / 10 = 310 Wh per mile 

You want to go 186 miles (300km) then you need a 58 kW battery

The motor has nothing to do with it.


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## Moltenmetal (Mar 20, 2014)

The motor size might be a clue as to the max speed and size of the vehicle. 5 kW isn't going to move a car very fast but might do for a bike.


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## Sunking (Aug 10, 2009)

pdove said:


> Take your vehicle weight and divide by ten.
> 
> 3100 lbs / 10 = 310 Wh per mile


Where does this formula come from? Sounds like a Ball Park estimate.


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## pdove (Jan 9, 2012)

Your mileage may vary


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## Sunking (Aug 10, 2009)

pdove said:


> Your mileage may vary


OK that answers my question, Ball Park napkin estimate.


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## dedlast (Aug 17, 2013)

Sun, 
It is a ballpark napkin estimate but it has a lot of real world observation that shows it is a very good ballpark napkin estimate. 

B


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## Sunking (Aug 10, 2009)

dedlast said:


> Sun,
> It is a ballpark napkin estimate but it has a lot of real world observation that shows it is a very good ballpark napkin estimate.


I have no problem with it. I learned something. Was just curious where it came from.


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## dougingraham (Jul 26, 2011)

Sunking said:


> I have no problem with it. I learned something. Was just curious where it came from.


It came from EVTV Jack and was confirmed with OEM manufacturers wh/mile figures and weights as an average of 9.97. The Tesla S is a smidge over 12 and others were worse averaging it out to about 10. Interestingly the DIY car Illuminati Seven does over 20 with this same calculation. I don't quite get 10 as an overall average with my car unless I am going highway speeds and then I do close to 11.


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## dcb (Dec 5, 2009)

Is it fair to attribute the illuminatis performance to streamlining for the most part?


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## Duncan (Dec 8, 2008)

I will add my own (appalling) numbers 
The Device is about 9 at 50Kph but this decreases to 4.5! at 100Kph
I attribute this to the terrible aerodynamics


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## dougingraham (Jul 26, 2011)

dcb said:


> Is it fair to attribute the illuminatis performance to streamlining for the most part?


From the little I have talked to Kevin I would say that it is due to paying attention to everything that could make a difference. Streamlining is certainly most important at highway speeds and is the one thing we really can't control when converting a car.


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## dcb (Dec 5, 2009)

Well it *can* be, depending on your conversion goals. Folks call it ugly, but it is a beautiful example of form follows function, well within DIY reach, and ~100mpg looks good, reasons not to be a slave to "fashion". I imagine it would be on the low end of w/mile if converted.


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## PhantomPholly (Aug 20, 2008)

dcb said:


> Well it *can* be, depending on your conversion goals. Folks call it ugly, but it is a beautiful example of form follows function, well within DIY reach, and ~100mpg looks good, reasons not to be a slave to "fashion". I imagine it would be on the low end of w/mile if converted.


Looks a bit like a 4-wheeled Aptera.


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## Suzan (Mar 10, 2014)

You can consult local mechanics of your area they have good knowledege.


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## zapyourrideguy (Oct 25, 2012)

just wanted to chime in on the guesstimate,
for my civic with Calb 180's at 144v running an ac-51 or previously on a zilla/8"ADC that 10% figure is almost dead on: 280wh/mile on dc 260 ish on AC. My calculated weight is right around 2700 lbs. Have never really weighed it since converting to lithium.


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## tharun232 (Nov 9, 2014)

Diesel Vechile Specifications(Auto Rikshaw)
Power [email protected] Torque 15.2 [email protected] Cubic Capacity 198.88 cc Transmission 4 forward + 1 reverse Kerb weight 405 kg
So i want to add electric motor in place of engine.
I'm thinking of 48 or 72v 10kw motor.
So much battery neede to run this vechile for 300km


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## kennybobby (Aug 10, 2012)

Using the 10% rule with a 900 lbs vehicle implies 90 Wh/mile performance.

To go 300 km = 168 miles

168 miles * 90 Wh/mile ~= 15000 W-wh battery pack

15000 W-hr/48V = 312 Amp-hr pack with 48 V

15000/72V = 208 Amp-hr pack with 72 V

Hope this helps, good luck with the conversion.


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## PhantomPholly (Aug 20, 2008)

I suspect 90Wh/mile may be too optimistic.

About a year ago we came to a rough comparison to gasoline. The rough conclusion was that 8Kwh pack capacity is about the same as 1 gallon of gas for purposes of propulsion, and assuming you never go more than 80% DOD.

This tracks with a Leaf. With a 24Kwh pack it goes about 90 miles, so that would be about the same as 30mpg.


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