My chair will often suddenly swerve right (downslope) when going across a slope and overreacts to joystick movements to correct.
This only happens when the motors are hot, after running for a couple miles or so. The controller, a VR2, gets warm but not hot.
Burgerman wrote:Its not the motors, but the power module. The motors have no heat sensors. The power module has, and it rolls back power if the load is too high and as it warms up.
I've just swapped out the Interstate AGM batteries for a new pair of MK's. One of the Interstate's has gone bad though it's just a few months old.
Since the motors use permanent magnets and permanent magnets get weaker as they heat up, I do suspect the motors first. It's possible they also may be mismatched? Rumour is that Sunrise tries to match motors as closely as possible. Or perhaps that's just marketing propaganda.
The motors do get pretty hot after a while especially when running at full speed for a couple miles or so, especially in summer. The controller is 70A, if I understand correctly from the exquisitely poor info I've been able to glean so far. I'm pretty sure the configuration is plain-old stock/default. Until I get the programmer that I want I'm only guessing here.
Oddly, this never occurs when crossing the slope in the other direction. Only when the right side is lower. And only when the motors are hot. The slope is about 15 degrees. On more or less level ground, or up and down slopes, it doesn't veer either way.
Burgerman wrote:Theres a surprise. Interstate are junk.
Burgerman wrote:Magnets in a motor are bonded to the case and are at the same temperature as the case. If it takes your skin off, that may be hot enough to demagnatise them slightly long term. But it doesent come and go.
And the magnets used are designed to get hot, at very least warm, and last many years. The rest of the motor dies first. In fact magnets that do get weak due to heat do that permenantly. The main thing that demagnetises magnets is high magnetic flux in the opposite direction. And even with a 120AMP controller that doesent happen. So its 99.9% certain that its got nothing to do with magnets or motor heat. And as your controller is only 70A so thats never going to happen. My own chair is programmed to go. And uses a 120A controller. And is rear drive which gives much more motor loading much of the time. And its double the weight of your own chair, and I am 20 stone! And my motors are identical. And they dont get hot enough to matter.
Burgerman wrote:This is 15 degrees. An official 4x4 off road ramp designed for testing suspension articulation in competitions. Steeper than you think!
LROBBINS wrote:Another possibility is that the clearance of the disc of the solenoid brake on one motor is off and that when the motor heats up it grabs.
Burgerman wrote:And these must be set correctly... If any are set a little low, esp temperature or current foldback level, and time, you will get the problems you are having. Further disguised by delayed steer settings shown above.
Burgerman wrote:I just measured them rolling along a carpeted room at about 1.5mph at: 10.2 and 9.1 Amps each. Sounds a lot? That was of course motor amps. Battery amps was 4.1A total. At about 25% max speed.
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