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



Dwight,
The 48V pack I have uses six 8V Golf Car batteries. It takes up practically no more space than six 6V batteries. (The 8V may be slightly taller, but its not an issue if installed correctly.) The stock ferro-resonant charger is used to charge half the pack at a time using a 24V square wave. I don't remember the rest of the details, but it's quite ingenious. I think it's similar to what the Landis charge controller does.

On Sunday, June 29, 2003, at 12:22  PM, Steve Richardson wrote:

Dave,

For sure you better gave three separate grounds!
Craig is correct..

Steve

scr echoweb net

----- Original Message -----
From: "Dave & Debbie Barden" <daveb seanet com>
To: <hazen indiana edu>; <agp vt edu>; <elec-trak cosmos phy tufts edu>
Sent: Saturday, June 28, 2003 2:20 PM
Subject: RE: (ET) E12S and a Curtis controller??


my new chargetek charger, the one that charges 3 12v batts, came in the
mail
yesterday.  My friend Craig has his doubts that it will work the way I
think it
will. That is NOT having to split the pack into 3 pairs of 6volt batts.
I
didn't ask but it sure sounds to me as though this charger does NOT have a common negative rather 3 separate negatives. Craig's point was that if I
don't
split the pack and the charger uses a common ground I have an immediate
dead
short.  Anybody out there know for sure.

this discussion about motors and controllers has indeed been informative.

dave
Seattle

I agree good discussion! IF the motors will take the extra voltage and
it sounds like they will then taking out the charger and replacing it
with a 6 volt battery sounds like the way to go. If you do not want nor
need the extra voltage just leave it the way it is. Using a modern
controller will make the number of connections less and we can use
larger wire and better connectors than the factory did. The bottom line is we may not need the extra battery to make up for all the voltage drop
in the old system. Has anyone put a voltmeter on the motor connectors
and driven up a hill to see how much it drops under load? My guess is a
lot. Even on cold days the wire bundles gat warm and the contactor
cabinet is warm, heat is loss. The voltage at the motor is what makes it
go not the voltage at the battery terminals.

It will be good to have a controller that we can program to set the
acceleration and deceleration! This is going to be fun!

The 36 volt battery charger that charges three 12 volts battery systems
looks interesting. My E20 wants one!

Steve, yes we need cruise control!

 Dwight

Dwight L. Hazen, Indiana University, UITS

Bloomington, In. 47408-7378

812-855-5367 IP phone 317-278-4014

hazen indiana edu http://php.ucs.indiana.edu/~hazen/

Ham Radio wb9tlh arrl net http://wb9tlh.ampr.us


-----Original Message-----
From: Andrew Poush [mailto:agp vt edu]
Sent: Saturday, June 28, 2003 10:33 PM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) E12S and a curtis controller??

Wow.  I am really pleased with the discussion that spun off my email.

David Roden is pretty accurate in what he says about Mark Hanson's
modifications.  I should know because I own one of the two E-15s Mark
modified. And I did my graduate studies in DC-DC power conversion and
motor control.  Mark did use two identical controllers, one for the
drive and one for the PTO. The battery pack is 48V and the accessories
are tapped off the pack.  I can put the tractor in any gear, vary the
speed command so that any voltage from 0 to 48V is applied, and it is
efficient and smooth. I never need to change gears while I mow. I can throttle down and switch to reverse in a blink, even if the tractor is
not quite at rest.  I never use the foot brake while mowing since the
reverse is so handy.  But my top speed is 4 mph whereas before the
modifications it would have been 10 mph. I don't really NEED the speed
for mowing and snow-plowing.  I just want it for the fun of giving my
daughter faster rides.

David did say that he would trust that since Mark put a second
controller on the PTO that it must indicate that running the mower deck
at 48V is too risky to attempt.  In fact, Mark told me just the
opposite. The mower motors can be run at higher voltage with little or no risk. I generally run them at 36V but crank them up when the grass
gets very thick.  I have run them that way for over a year and never
tripped the thermal overload or gotten the motors hot enough that I
couldn't hold my hand on any one of them indefinitely. This E-15 is a
great ride and I only look forward to it getting better if this kit
Steve's company is developing can be made affordable.

One more feature I would like to see on a controller for the ET is
cruise control.  The ability to set a cruise speed and then reduce
speed (or even reverse direction) for maneuvering around obstacles and then resume the preset speed would be very useful to me. Currently, I
can set a speed but cannot resume it after changing speed.  The speed
command input to the controller is a slider potentiometer next to the
forward/reverse switch (rather than a foot pedal). I am not sure that
a foot pedal is compatible with implementing a cruise control cost
effectively.  What do you think, Steve?  Is cruise control a
possibility?

Andy

PS - I will never go back to a 36V battery pack.



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