Running Etek CCW
I think the etek was meant to run CW as there is a squealing sound when I run it in the other direction that comes from the brushes.
I think I messed with the timing and didn't get it back to neutral a while back, but I did a no-load test anyway:
CW @ 12v: 3.0 amps
CCW @ 12v: 3.10 amps
I heard of someone smoking a PMG 132 motor running it CCW here, so that got me a little worried. I talked to Brian at thunderstruck-ev.com, and he said that someone in Australia was running two eteks horizontally opposed in a car and one kept smoking. It was the one that was being run CCW. That got me a bit more worried. He also said that the brushes are going to wear a lot faster.
I think I can keep the current to each motor equal by advancing the timing on the CW motor if the CCW motor at neutral timing just happens to be drawing more current.
Anyone have any experience with this, or ideas/comments?
I remember something similar with an etek turning the wrong direction in the old forums and cant remember how it was fixed and who it was. I dont remember if the guy had to turn it back in to get the correct direction or was able to change the direction of the brushes. Unfortunately, I do not have my etek available with me to look at this time to check the brushes. Maybe Badfishracing has some advice on this.
Some adjustment of the timing would be needed to reverse the direction. I'm not sure if the slots have enough adjustment range to get it dialed in for reverse. If you run the motor slow (12v) and measure the no load current, adjust the brushes until the current is minumum. This will be very close to where you want to be. It might be necessary to elongate the holes to get enough adjustment.
Remember, you're trying to change the position of the brushes with respect to the magnets to change the timing.
If the motor is reversed, the brushes will need to "break in" in the reverse direction. This can be done by running the motor for a few hours at low speed. Avoid high current operation until the brushes are fully seated in the new direction.
do you have any contact info for badfishracing?
Just FYI you can't rotate the brush holder on the etek. This is because the brushes run through holes in the cast motor housing. Rotating the brushes might make them contact the housing. Instead you can rotate both magnet rings. I'm not sure how to get the magnet rings lined up with each other, because you rotate them independently. I think I'll adjust one for lowest current operation, then do the other one?
I always thought advancing the timing was rotating the brushes with respect to the magnets in the direction of rotation. Or is it the other way?
OK, now I remember.
Anyway, you want to try and keep both magnet rings lined up with each other (move both of them the same amount).
To advance the timing, the magnets would need to rotate in the same direction as the shaft.
Your currrent measurements indicate the timing was pretty close to neutral. At neutral, the forward and reverse current will be equal. Since the Etek has such a low inductance, you don't need too much advance. I'm not really sure what optimal is, but in general, neutral is best at low RPM and more advance is best for higher RPM.
Got this response from the EM ListServ:
On the Lemco or Agni motor, the brush gear can be moved for optimal
performance in either CW or CCW rotation. For use where the motor will be
run at full load in both directions (say a fork lift) the brushes are timed
neutrally. The Etek does things a little differently. The brushes are fixed,
but the magnets can be moved. That's what the slots on the case are for.
The brushes will be fine in either direction, but they need to be run-in
because the brushes are able to tilt slightly in the holders. When the motor
is run in reverse rotation the brush tilts the other way and brings a sharp
edge into contact with the commutator. That gives rise to the squeaking
noise and means you only have a small contact area. If you combine this with
the wrong brush timing, then you have a motor that is likely to fail. You
need to seat the brushes by running the motor on the bench for quite a few
hours, or by using a brush stone.
When the brushes are run in, you can adjust the timing. The simplest way
when you have two motors electrically and/or mechanically in parallel is to
adjust them to run at the same rpm.