Questions to the list.

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Questions to the list.

Kenneth G. Gordon
I have a question or two for the collective wisdom:

1) What sort of instrumentation would you consider to be of
importance in an EV?

I had thought that in addition to a voltmeter, an ammeter,
perhaps a tach, and possibly some sort of more
sophisticated meter which would measure remaining power
left in the batteries, and/or an SOC measuring device,  one
might also want to know the temperature of the motor, the
batteries, and the controller.

2) What, if any, are the trade-offs between direct-drive (no
transmission), and using the transmission that might come
with any auto I might wish to convert?

3) Of course, there would be more losses with a
transmission between the motor and differential, but is that
loss significant?

4) From what I have gathered here so far, it seems that
direct drive should be used pretty much only for either a very
light car, or for a dragster, and that for heavier vehicles, a
transmission would be a better idea. Am I correct?

I am thinking that although the torque curve for a good
motor seems pretty flat, there must be a point in that curve
where current draw is minimized, and I am also thinking that
it might be pretty close to the high end of the motor's RPM
range.

It also seems to me that using a transmission should
minimize the massive current draw when starting from zero
RPM.

5) If so, where is the break-over point in weight for when
direct-drive vs a transmission should be used?

6) It seems to me that higher voltages, which result in lower
current draw for the same power output, would be better
than lower voltages, but then the weight of the necessary
batteries would be an important factor to consider. Is there a
"break-over" point where higher voltages definitely become
an asset?

I suppose that higher voltage could also be gotten by using
smaller batteries, but more of them. The voltage being
higher could also minimize ohmic losses in the connections
and cables, I would think, since the current would be lower.
And lower current with the resistance in the cables and
connections being fixed would mean less voltage drop.
(E=IR)

7) Is there a scalable relationship between voltage and
weight of vehicle? I.e, is it better to use higher voltages with
heavier vehicles, and vice versa?

8) Is keeping the total weight as low as possible, and rolling
friction at a minumum, the only way to extend range when
using standard flooded batteries?

9) How do you accurately measure rolling friction?

10) Is there a book available that can answer most of these
questions?

If not, I'll have more questions later. :-)

Thanks!

Ken Gordon

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Re: Questions to the list.

gottdi
There are books but you have more collective wisdom and real world  
stuff right here. Do your homework before you ask questions and ask  
smartly. Ask questions one or two at a time. You just blasted us with  
enough information to write a small book.

:  )

I am still learning.

On Feb 20, 2008, at 10:11 PM, Kenneth G. Gordon wrote:

> 10) Is there a book available that can answer most of these
> questions?

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No need to wait any longer. You can now buy one off the shelf. You can still build one too.
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Re: Questions to the list.

Kenneth G. Gordon
On 20 Feb 2008 at 22:26, [hidden email] wrote:

> There are books but you have more collective wisdom and real world
> stuff right here. Do your homework before you ask questions and ask
> smartly. Ask questions one or two at a time. You just blasted us with
> enough information to write a small book.  :  )

Ooops! Oh, dear! Well, I HAVE been spending an awful lot
of time on the net, reading everything I can get my keyboard
around. Still, a nice book would certainly help with the
"homework". :-)

That way I wouldn't have to tell SWMBO what I am doing
every time she asks.

> I am still learning.

Boy! Me too! Am I ever!

Thanks for the answer. Much appreciated.

Ken Gordon W7EKB

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Re: Questions to the list.

Bob Bath
In reply to this post by gottdi
I'm sure someone suggested "Convert It" by Mike Brown
of ElectroAutomotive, but that gave me my start.

--- [hidden email] wrote:

> There are books but you have more collective wisdom
> and real world  
> stuff right here. Do your homework before you ask
> questions and ask  
> smartly. Ask questions one or two at a time. You
> just blasted us with  
> enough information to write a small book.
>
> :  )
>
> I am still learning.
>
> On Feb 20, 2008, at 10:11 PM, Kenneth G. Gordon
> wrote:
>
> > 10) Is there a book available that can answer most
> of these
> > questions?
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


Thinking about converting a gen. 5 ('92-95) Honda Civic?  My $23 "CivicWithACord" DVD (57 mins.) shows ins and outs you'll encounter, featuring a sedan; a del Sol, and a hatchback, each running 144V/18 batteries.  It focuses on component/instrumentation/battery placement and other considerations.  For more info,   http://home.budget.net/~bbath/CivicWithACord.html
                          ____
                       __/__|__\__
             =D-------/   - -     \
                      'O'-----'O'-'
Would you still drive your car if the tailpipe came out of the steering wheel?


      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page.
http://www.yahoo.com/r/hs

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Re: Questions to the list.

Kenneth G. Gordon
On 21 Feb 2008 at 6:49, Bob Bath wrote:

> I'm sure someone suggested "Convert It" by Mike Brown
> of ElectroAutomotive, but that gave me my start.

Thanks. I'll order it asap.

Ken Gordon

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Re: Questions to the list.

Kenneth G. Gordon
In reply to this post by Kenneth G. Gordon
On 21 Feb 2008 at 10:38, [hidden email] wrote:

<much good answers snipped>

Thank you very much for the kind answers, Mr. Beard! Much appreciated.
Now, I have a lot of reading to do!

Ken Gordon W7EKB

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Re: Questions to the list.

Doug Weathers
In reply to this post by Kenneth G. Gordon
Hi Ken,

You will probably also benefit from reading "Build Your Own Electric
Vehicle", by Bob Brant.  It's got a lot of answers to the questions
you've asked about EV theory.

<http://www.amazon.com/Build-Your-Own-Electric-Vehicle/dp/0830642315>



Kenneth G. Gordon wrote:

> On 21 Feb 2008 at 6:49, Bob Bath wrote:
>
>> I'm sure someone suggested "Convert It" by Mike Brown
>> of ElectroAutomotive, but that gave me my start.
>
> Thanks. I'll order it asap.
>
> Ken Gordon
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

--
--
Doug Weathers
Las Cruces, NM, USA
http://www.gdunge.com

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Re: Questions to the list.

Dmitri-7
In reply to this post by Kenneth G. Gordon
Basically, you'd have less problems/costs using a transmission, so just go
with a transmission.
High voltage is good, as you say, but the cost of components goes up, so
it's a balance one needs to make. Go as high as possible without the need
for more expensive ones.

> 8) Is keeping the total weight as low as possible, and rolling
> friction at a minumum, the only way to extend range when
> using standard flooded batteries?

No. Lower weight mostly minimizes your costs, but range mostly depends on
the proportion of battery you have to the finished total weight of the car,
air resistance(frontal area and coefficient of drag), rolling resistance,
and driveline drag.
You generally want 1/3 of your finished weight in batteries.
Good examples: http://www.evalbum.com/1430 and http://www.evalbum.com/037 
These have almost 1/2 of weight in batteries. Very heavy, expensive(40
batteries!), but long range.

> 9) How do you accurately measure rolling friction?

I think there were some posts on the EVDL on measuring it. Try searching the
EVDL archive about measuring rolling resistance or friction.

----- Original Message -----
From: "Kenneth G. Gordon" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Thursday, February 21, 2008 1:11 AM
Subject: [EVDL] Questions to the list.


>I have a question or two for the collective wisdom............

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