Re: (ET) E12S and a curtis controller??

[Jim Coate <jbc coate org>]

Hi Steve -

Keep in mind that ~many~ accessories are available for the ET, all
designed for 36 volts. Some like the mower deck use PM motors that won't
take kindly to being run on a higher voltage. (yeah, could add another
controller but that adds cost & complexity). Also, changing pack voltage
requires a new charger.

For your own use, it could be fun to up the system voltage, but as a
test bed for a new product I'd suggest sticking to the 36 volts that
most customers will be using.

As for the field current, there is indeed a definite ratio with the
armature current that results in maximum efficiency (at least for a pure
sep-ex motor). I found a journal article from the 1960's that discussed
this and showed the test data, and my dad derived the same equation
analytically. (I'll have to dig up the reference). But in real life
there are times when need full field to get maximum torque or reduced
field for maximum speed. So will be interesting to see what that micro
is programmed to do.

- Jim, who's E-20 would look sooooo nice with a new controller.

Steve Richardson wrote:
> The Alltrax controller automatically adjust the field strength to keep it
> within a percentage of the of the armature current.  The armature current
> and the field current is monitored by the microprocessor and it decides,
> based on programmable variables, what the percentage should be.
>
> <snip> Another option, one I'm going to try, is use a
> 48v battery pack since the our controllers work on voltages from 24 to 72
> volts, depending on model.

_________
Jim Coate
1992 Chevy S-10
1970s Elec-Trak E20
http://www.eeevee.com