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Re: (ET) Controller Needed?



Most efficient speed is full field, full armature power.

If you weaken the field the speed goes up, but the power goes down and more energy becomes heat in the armature. Resistors of course create heat as well so they are less efficient.

Chris

Pieter Litchfield wrote:

So on my E-15, which is the "most efficient" speed in terms of run time?  I
have been assuming it is the third (?) speed above stop on the controller -
at the "notch" in the controller.  Beyond that is field reduction, below it
is amerature limiting via resistance as I understand it.  I have always
assumed that in "direct drive" I am making the most efficient use of 
battery
power, but is this correct?  For example, all else being equal, would 
mowing
the lawn in 2nd gear (physical gearbox) at top speed (controller) be as
efficient as 3rd gear (physical gearbox) in direct drive (controller)?

-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Christopher
Zach
Sent: Wednesday, June 09, 2004 2:15 PM
To: daveb
Cc: perry suppleye com; elec-trak cosmos phy tufts edu
Subject: Re: (ET) Controller Needed?



the problem with the original set up of contactors and resistors is the

waste

of energy to go slow by "shunting" the excess up to big resistors where

the

energy is wasted as heat that does nothing.


Problem is relative, how many of us spend 95%+ of time at full speed in
some gear?

True I do like to go manual and into the low speeds every once in
awhile, but most times I spent in speeds 4-7. Speeds 1-3 are simply
there to buffer the E20's motor.

Chris


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