[ausev] Hoping for some answers

[Brian Lasseter]

On Wed, Apr 15, 2009 at 9:58 AM, red scott <redscott77092 at yahoo.com> wrote:
> Right  - no "speed" control needed but some kind of surge protection might
> help....I'm guessing, I'm not the electrician here.

You should probably have something to limit current inrush... Like
this person says he is using a pair of 2-ohm resistors on his
lawnmower:  http://www.evalbum.com/1522

Electricity is best thought of like water in my mind... voltage being
like water pressure, and current being like the amount of water in the
pipe.

By limiting inrush, you get an effect like turning on the tap slowly,
instead of hitting your motor with a huge wall of current all at once.



As for figuring the speed... You measure the voltage, and resistance
of your set of batteries... then measure the resistance of the motor.
You add the two resistances together, and with the V=I*R formula...
you can figure out how much current (I) will flow since you know the
voltage (V) of the batteries, and the resistance (R) of the system.

Using motor spec charts, like this one for the A000-4009 motor
http://www.evmotors.com.au/products/download/AOO-4009.pdf you can
calculate the exact RPM and torque your motor would generate at a
given voltage and current.  (Though the voltage of your batteries is
likely to sag as you get above 100A of current.  I see about a 20%
voltage sag at 300A.)



-- 
TTFN,
Brian "Lasso" Lasseter

"No Sane man will dance."   -Cicero (106-43 B.C.)