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Battery Reloq. - wire size, routing, battery location etc.



Sorry, I replied before reading the second post because I thought it was a
duplicate.  I understand your explanation about the moment of inertia, but I
don't consider that a particular weakness of these cars, whereas weight
distribution definately is.  The moment of inertia added by a mass (like a
battery) is proportional to the square of that mass's distance from the
c.o.m., so a little change can make a decent difference.   I'll be moving
the battery from 14" in front of the front wheels to about 14" behind the
rear wheels.  Unfortunately, the center of mass of my car is something like
35 inches behind the front wheels, so the battery is moving 25 inches
further away from the C.O.M., whereas it's the same distance from your box.

So what I'm doing is worse for moment of inertia than you probably thought
it was, but I'm pretty sure the weight distribution benefits will far
outweigh that.   The problem with these cars is that they try to rotate
around a point really close to the already-overloaded front wheels.  Move
that weight further rearward and the rear wheels cna finally start chipping
in on turns.

Also note that inertia affects only apply to rotational acceleration, or
initial turn in.  They would actually help turn-out at the end of the turn,
I think, by theoretically reducing understeer.  For the constant radius that
is the middle of most turns, the moment of inertia (I) has no affect
whatsoever.

Here's how I think of it.  Consider that getting a 45lb weightlifting bar to
rotate is harder than spinning a 50lb free weight dangling from your hand.
However, both of these are easier than spinning, or even picking up a 50lb
weight attached to the other end of a broomstick.  Balance is key.

BH

----- Original Message -----
From: <jester@westfailure.net>
To: Brian Haygood <scirious@hotmail.com>
Sent: Wednesday, March 27, 2002 8:12 PM
Subject: Re: Battery Reloq. - wire size, routing, battery location etc.


> I re-read my post and thought i'd make it clearer...
>
> If you relocate it from in front of the front wheels, to behind the rear
> wheels, you are moving your moment of inertia problem to the other end
> of the car, not improving it.
>
> This may or may not handle better, but the moment of inertia thing is
> caused by how far a weight is outside the "box" formed by making a line
> across the axles and between the front and rear axles. (well, specifically
> that might not be right, i think its distance from the center around which
> the car rotates when turning, but the box thing is simplistic enough i get
> it hehe)
>
> hope that helps?
>
> take care,
>
> Steve
>
>
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