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  #11  
Old 05-20-2012, 06:13 PM
yangsword9x yangsword9x is offline
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Default Re: Help me plan my Van conversion!

Quote:
Originally Posted by mora View Post
Something must be going wrong. You definitely don't need 900kWh of batteries to accomplish your range goal at that speed and with that weight. Are you sure you are driving the van pedal floored all the time?

Let's say you have 256V (80x 3.2V lithium cells). If these are 180Ah and you paraller 6 of them you get 180Ah x 3.2V x 80V = 276kWh of energy. You can get about 1.75 hours of driving if you use 256V x 600A all the time. That's about 6000lbs of batteries.

I also believe none of mentioned motors can take 600A loads continously.

The car you linked (RAV4) only has 31kWh of batteries and can go 100 miles at 55mph. That's 156V/200Ah. It consumes about 300Wh/mile at that speed. You are going to go faster so consumption per mile will be higher. I'll throw a figure out of hat: 600 watts/mile. If you want to go 140 miles, you need 84kWh of batteries. At 256V it means 328Ah batteries (180Ah x 2 = 360Ah), which should do. That's less than 2000lbs of batteries.

Feel free to correct my thinking and maths.
Correct me if I'm wrong, but I read that the amps needed to be multiplied by the hours that you drive.
Would'nt that be 450 amps * 2.32 hours = 1044 amp hours needed total?

For each hour that I drive, my set up consumes 450 amps (If I'm flooring the pedal all the way down).
Since I'm driving for 2.32 hours, for each of those hours I have to consume 450 amps right?
SO the math would be 450 amps/hr.
450 amps * 2.32 hours = 1044 amp Hr. NEEDED! RIGHT!?


Amps must be consumed from the amps, not from the volts right? or watts?

Last edited by yangsword9x; 05-20-2012 at 06:59 PM.
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  #12  
Old 05-20-2012, 08:02 PM
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Default Re: Help me plan my Van conversion!

Even floored all the time you don't run at full power for longer than your peak acceleration. My car (with a max of 400A) during about a 10 second acceleration period will only be over 200A for half that time, and over 300 for a second or two.

You don't consume amps or volts, you consume power, which can be measured in watt-seconds (joules) or kWh.
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  #13  
Old 05-21-2012, 05:28 PM
yangsword9x yangsword9x is offline
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Default Re: Help me plan my Van conversion!

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Originally Posted by Ziggythewiz View Post
Even floored all the time you don't run at full power for longer than your peak acceleration. My car (with a max of 400A) during about a 10 second acceleration period will only be over 200A for half that time, and over 300 for a second or two.

You don't consume amps or volts, you consume power, which can be measured in watt-seconds (joules) or kWh.

So you're saying that is I needed 100,000 watt hours,
I can configure the batteries to be 200 volt by 500 amp, or
500 volt by 200 amp, and both configurations would work regardless because its all about the watt hours consumed and not the amp hours?

Okay then, after all of you guy's input, since a 6000 lb truck can go 70 mph at only 102 volts by 400 amp battery configuration, than I'll just add a little more volts to that.

80 mph/ 70mph = 1.143 % more needed watt power to achieve (made up)
1.143% x 102 volts = 117 volts
3.2 volts x 37 in-series = 118.2 volts
37 x 12.34 lb = 456.58 lb
456.58 x 2 parallel = 913.16 lb

Last edited by yangsword9x; 05-21-2012 at 05:50 PM.
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  #14  
Old 05-21-2012, 05:47 PM
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Default Re: Help me plan my Van conversion!

Basically, but it's actually volts and amp-hours (AH) and 200V would be much more typical than 500V. amp-hours times voltage gives watt-hours. What is not as important for your calculations is AMPs, which is the momentary current draw. You must size your system to provide sufficient amps to move you, but the batteries are primarily sized based on the average wh/mile you will need.
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  #15  
Old 05-21-2012, 05:48 PM
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Default Re: Help me plan my Van conversion!

Both configurations would give you roughly the same energy. With high current, there may be more losses in the wires, but with high voltage, there may be more losses in the controller power electronics. So it all balances pretty well.

100 kWhr by DIY EV standards, and even by professional EV standards is huge.

900 kWhr is..... like a backup powersupply for a section of the grid
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  #16  
Old 05-21-2012, 06:14 PM
yangsword9x yangsword9x is offline
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Default Re: Help me plan my Van conversion!

Quote:
Originally Posted by subcooledheatpump View Post
Both configurations would give you roughly the same energy. With high current, there may be more losses in the wires, but with high voltage, there may be more losses in the controller power electronics. So it all balances pretty well.

100 kWhr by DIY EV standards, and even by professional EV standards is huge.

900 kWhr is..... like a backup powersupply for a section of the grid
Well if high volts and amps causes problems for the controller and wires, then I'll just make them equal: 180 volt in-series by 180 amp hours parallel.
That should make the problems equal...

http://www.ev-power.eu/en/LiFeYPO4-b...P12V180AH.html

BUT I'LL JUST USE THE BATTERY PACK LISTED ON MY FIRST POST, IT HAS CHARGER TOO!!!

180 volts / 12 volt battery = 18 batteries in-series
180 amp hr./ 180 amp hr. battery = 1 battery parallel
18 in-series x 1 parallel = 18 batteries total
18 x 56 lb = 936 lb total

Last edited by yangsword9x; 05-21-2012 at 07:00 PM.
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  #17  
Old 05-21-2012, 10:13 PM
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Default Re: Help me plan my Van conversion!

180/12=15 in my book.
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  #18  
Old 05-21-2012, 10:23 PM
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Default Re: Help me plan my Van conversion!

It has a charger for that pack, or for the full series pack?
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