Posted by nicksanspam on September 16, 2007, 7:02 pm
At 2:30 on Saturday in the yellow flag tent (1 of 8). PhD Nathan Hurst
will be talking about his Mazda radiator solar heating experiments in
Australia at 3:30 on Sunday in the red flag tent (a late program change.)
PhD Rich Komp will be talking about energy-efficient food storage at 3:30
on Saturday in the blue flag tent and new developments in photovoltaics
at 4:30 on Sunday in the white flag tent. We'll be at an "ask the engineer"
table at other times. About 6,000 people came the first year and 12,000
last year. Will there be 24,000 this year? :-)
BTW, it would simplify the damper arrangements if we could pull hot sunspace
air through the radiator with its fans during the day to heat water and push
house air through it to heat the house at night. Does anyone know if late
model Japanese radiators (eg my $5 '95 Mitsubishi 2.0 Eclipse) 12V fans have
brushes that are slanted in the normal rotation direction in a way that lets
the commutators quickly grind them up in reverse?
Posted by .p.jm on September 16, 2007, 7:27 pm
On 16 Sep 2007 15:02:03 -0400, email@example.com wrote:
That would be during your potty break, I assume ?
PHDs ! PHDs! PHDs ! Boy howdy mama, gotta be some good
stuff there with all dem PHDs !!!!
Sounds like a good weekend in Reno.....
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Posted by nicksanspam on September 16, 2007, 7:34 pm
Just a part of one. We could do this with about $00 of standard HVAC stuff.
My mechanic friend says no. Reversing should be OK.
Posted by Neon John on September 16, 2007, 9:14 pm
On 16 Sep 2007 15:34:25 -0400, firstname.lastname@example.org wrote:
You're mechanic friend is wrong for most automotive DC motors. The issue isn't
slant because most small motors don't use brush slant. The issue is brush
The reaction of the field and armature magnetic fields forces the field toward
edge of the pole. It is desirable to commutate at a zero potential point and
means where the field is weakest. Therefore brushes are advanced over the static
timing to the new dynamic neutral position. If the motor is reversed without
re-timing the brushes, there will be heavy sparking, rapid commutator and brush
high current draw, overheating and low power. The timing changes with load but
a fan is a more or less constant load, static timing works.
Larger more expensive DC motors frequently have "interpoles", also known as
"commutation windings" to stabilize the commutation point but small cheap
The old EV warrior electric bicycle used two Ford radiator fan motors for
One on either side of the wheel, shafts pointing toward each other with a rubber
roller connecting the two. The roller contacted and drove the tire. These
came in left and right-hand rotation versions.
If one attempts to run one backwards it does everything I described above. When
company went bankrupt I bought a box full of the motors and have used them on a
variety of small EV projects so I'm quite familiar with the characteristics.
On the web there are various descriptions of techniques people have used to
these motors. For some reason there were many more of one type than the other
surplus market so there was a demand for reversing techniques. It looked like a
of work to me, for this motor uses a radial commutator and the brushes are
the end bell plus the motor is assembled with crimped joints.
John De Armond
See my website for my current email address
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
You have a magnetic personality... That must be why all your mental floppies are
Posted by Anthony Matonak on September 16, 2007, 11:24 pm
Neon John wrote:
I guess the simple solution would be to bolt another fan on the other
side of the radiator.