floodies will trash the batteries pretty quickly. I think you can only do

that from 6V floodies, and then not often. Might want to model a pack of 6V

floodies.

Now if we could model a dozen 12V floodies in parallel with a dozen 12V

AGM's...

Marty

----- Original Message -----

From: "Joseph T. " <[email protected]>

To: <[email protected]>

Sent: Monday, August 13, 2007 1:35 AM

Subject: [EVDL] Real HP in an EV ?

>I ran some number to find what the real hp would be in a typical EV,

> just to get an idea of the kind of performance to expect from a

> flooded conversion.

>

> For this I used some basic equations from zeva.com.au (great website

> by the way!)

>

> So I tallied up the internal resistance (or ohms) in all the batteries

> plus the wiring losses. I left out the losses in the contactors and

> whatnot since I'm assuming it would be minuscule and I don't know

> where to find that info.

>

> So, as I'm sure many of you know, to find power loss you multiply

> resistance by the square of current.

>

> So I took the internal resistance, or ohms, of each battery and

> multiplied it by how many batteries there would be. In this case, I

> took 12 12 volt J-150 batteries, which have an internal resistance of

> 0.0036, as per evconvert.com. I assumed a use of about 20 feet of

> copper, which came up to 0.00154 ohms. I know that basically the max.

> amount of current you can safely pull out of flooded lead-acid is 500

> amps, so I used that as my current. Here's the math!

>

> 12 * 0.0036 + 0.00154 = 0.04474 ohms.

>

> P=500*500*0.044174

>

> So the power loss is around 11 kilowatts. The amount of power

> available, without resistance, is 72 kilowatts (144votls*500amps) So

> the real amount of power is 61 kilowatts. Then you have to multiply

> that by the controller and motor. So it comes down to: 61*.95*.90=

> 52kw or about 65-70hp.

>

> I have come to the conclusion that you can either have cheap flooded

> batteries with so-so performance, pricey AGMs with great performance,

> or the lithium based batteries that cost a fortune but in the long run

> are the better solution.

>

> So anyway, were my numbers right?

>

> _______________________________________________

> For subscription options, see

> http://lists.sjsu.edu/mailman/listinfo/ev

>

>

_______________________________________________

For subscription options, see

http://lists.sjsu.edu/mailman/listinfo/ev