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Howdy to All,
In a recent reply to "Voltage Dip,"
Steve Richardson commented (below), "The controller will run on 24 volts
(actually 24-48 volts)." This comment started my brain
along a train of thought...forgive me for not completing it myself.
I got brain-lazy, and I thought I'd bounce the initial stages of this
thought-train off y'all and see what kind of feedback I might be able to stir
up. Here, below, are the highlights of my initial
thinking. Are my assumptions false? Are my conclusions
erroneous? Whaddaya think?
- There are so many nice 24VDC or 48VDC battery chargers
and inverters available, it might be nice to operate the Elec-Trak on either
24VDC or 48V instead of 36V.
- If the AllTrax will accept a 48VDC input, making use
of the programmable current-limiting feature, perhaps it could safely operate
the stock 36VDC motor with a 48VDC source.
- Motors are directly damaged by excessive
current...only indirectly by excessive voltage.
- As shaft load increases, shaft speed slows...as
shaft speed slows, the internally-generated CEMF is reduced...as the CEMF
is reduced, the net forward voltage on the armature increases...as the net
forward voltage on the armature increase, the forward armature current
goes up...if the forward current goes too high, the armature gets
fried.
- If the Alltrax can indeed limit the forward armature
current to the rated Full-Load Amps (or Service Factor Amps), then
regardless the voltage applied through the controller, the motor should not
be damaged.
- Perhaps the AllTrax will allow the stock 36VDC motor
with a 24VDC source.
- On 24VDC a 36V-rated motor will turn slower than
rated, potentially leading to shaft-over-loading, resulting in a reduced
CEMF.
- Reduced CEMF, leads to excessive forward current,
as described above.
- Perhaps the Alltrax can indeed limit the forward
armature current to the rated Full-Load Amps (or Service Factor Amps), and
perhaps the motor would not be damaged.
- The on-board ET charger could be removed and the
vacant space filled with 2 additional 6V batteries...Eight, 6V batteries could
be tied into a single series string for a nominal 48VDC, or into two 24V
strings that are tied together in parallel. An external charging station
could be set up and connected to the tractor via a heavy-duty, Anderson-type
DC plug.
Of course, these thoughts don't address
what to do about powering the mower deck, or other power-attachments; but, in
the words of Scarlett O'Hara, "I'll think about that another day."
(Although...they could be equipped with 120vac motors and be
inverter-operated...maybe...).
Any thoughts, feedback, or
criticism? Am I way off base...or just a little off
base?
Thanks,
Tim Wilhelm
E-16 being rebuilt, with AllTrax ready to be
installed.
----- Original Message -----
Sent: Tuesday, May 11, 2004 7:33 PM
Subject: Re: (ET) Voltage dip
Ralph,
The easiest way to test the batteries under load
is get a jumper the size of the battery cables and jumper out each battery one
at a time. The controller will run on 24 volts (actually 24-48
volts). Run the ET around normally. The only difference you would
see is in speed. When you jumper out the bad battery (if that's the
problem) the symptom will not occur. The current and voltage both
drop because a resistance is being added to the circuit somewhere, most likely
in one of the batteries if nothing else is getting hot.
Steve Richardson
Alltrax Inc.
541-476-3565 work
----- Original Message -----
Sent: Tuesday, May 11, 2004 1:19
AM
Subject: Re: (ET) Voltage dip
Steve, I have 4 computers and none of
them can run XP. I use a legal size scsi scanner and a CDRW that
cannot be made to run on XP. I also run CadCam software that needs dos
and will not run on a machine with XP. I can't do a load test because
the problem doesn't last long enough. I will have to take the cover
off to check the solenoid temperature.
G M Bauman, The internal thermal switch
is wired in with the seat & brake switches so it should be
working. I pulled a 800 pound roller around for 2 hours and it didn't
shut off. I heard that motors running on PWM controllers do run
hotter.
Jim, The main disconnect switch is the
new style from Bill Gunn. I installed it last fall.
Michael, The AllTrex doesn't use
forward/reverse contactors, it is solid state.
I was wondering if I had a cell in one of the
batteries that had an intermitent short, If I do wouldn't it only drop
2 volts? I appear to be dropping about 8 to 12 volts on the fuel
meter. The fuel meter is new, I just installed it last month. It
checks good with my other voltmeter. I don't understand why when the
voltage drops the current on the load meter also drops a little. If I
had a short circuit the current should go up? The batteries stay cold,
all battery connections and cables are new and they stay cold.
Thank you for your thoughts
Ralph Vogan
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