Brake by reversing

[Pontus]

Last years folding propeller was swapped out for a one with 3 fixed blades, in order to to get re-gen working.

This means the propeller is often coasting along, even at slow speeds inside harbours for example. Manoeuvring a 4 T sailboat in tight places often requires shorts burst of high thrust, in order to get a good amount if water flowing past the rudder for steering. This also implies rapid shifting between forward and reverse.

What I've noticed is that the motor wont start in another direction than the one it's coasting in, i.e. if the boat make speed through the water going forward coasting, it cannot be started in reverse in order to brake. Even worse, the controller seems to stop and needs to be power cycled in order to start. Stopping the propshaft by hand makes it possible to run in reverse. The exact same happens the other way around; I cannot run forward if the prop is coasting by the boat moving backwards.

In a land based vehicle this is of course a desired behaviour, but on a boat that's obviously not the case This is not only annoying but downright dangerous.

I first thought it was possible to solve this by increasing the stall protection time and/or increase start current of the controller. But even with 4 s stall protection time and 150 A as starting current it simply cannot be started in the other direction.

Is there a setting for this that I might have missed? Without a solution, this is an absolute showstopper.

[Bikemad]

Unfortunately, I am not aware of any programmable setting for the VEC controllers that would have any real effect upon this particular problem.

It could be that your propeller diameter or pitch is simply too large for direct drive with this motor, as the starting torque of the motor appears to insufficient to overcome the amount of torque being produced by the spinning propshaft while the boat is coasting.
Think of it in terms of a car whose gearing is too high to allow adequate engine braking on hills and also stalls easily while trying to pull away because the high gearing cannot apply sufficient torque to the wheels when trying to take off from a standstill.

I don't know whether the EBS Auto-Mode is supposed to work with a boat type throttle in the Neutral position, but I seem to recall that the manually switched regenerative braking only works when the motor is spinning in the default forward direction of rotation, as it does not work if the motor is running in the switched Reverse direction.
Do you know what the lowest rpm value is that the EBS Auto_Mode Speed (rpm) setting will accept?

Do you have access to a smaller diameter and/or reduced pitch propeller you could temporarily fit to see what difference it makes to the low speed forward/reverse manoeuvring?
If you don't experience the same problem with a smaller propeller, then adding the correct gear reduction to the existing propeller may hopefully cure the problem as well.



Alan
 

[Pontus]

Both the diameter and pitch is in line with boat speed and rpm. After some more testing it seems the motor not even tries starting when it's coasting in the opposite direction, like there's a built stop that not even lets you try reverse to brake. Also, the motor won't start after a power cycle if the prop is coasting when the controller starts, regardless of direction.

I'm not sure what the lowest value for EBS-auto is but 120 rpm is ok. I haven't got EBS-auto to work any way.

I did however got the following reply from GM, which feels like a real bummer. 

Please swap to our new controller with new throttle .
 
You old set doesnt fit boat at all .

[Defuzo]

Unfortunately, I am not aware of any programmable setting for the VEC controllers that would have any real effect upon this particular problem.

VEC controller? not tobe confused with the Vesc-project (opensource controllers)?

I have similar issues with MP2 (ebike hubmotor), I can run it in reverse. But if I touch that button while running forwards, I haveto come to complete stop, before going in ether direction. (had to change the parameter for regen-break to 80%, because my 36v battery became overloaded, -so thats not the solution)

[Bikemad]

I did however got the following reply from GM, which feels like a real bummer.

Please swap to our new controller with new throttle .
 
You old set doesnt fit boat at all .

That's definitely not what you wanted to hear. 

Perhaps you could rig up some form of mechanical brake on the propshaft that could be temporarily engaged in the Neutral position during manoeuvres.
Whilst I appreciate this is not an ideal solution, it should be a lot cheaper than replacing the controller and throttle, and perhaps it could be activated by an electrical solenoid controlled by a microswitch on the throttle mechanism to automatically engage the brake in the Neutral position.

You could then add a simple change over switch (Regen switch) to automatically disable the propshaft brake and enable the Regenerative braking simultaneously, as you wouldn't want both activated at the same time. 

Unfortunately, I am not aware of any programmable setting for the VEC controllers that would have any real effect upon this particular problem.

VEC controller? not tobe confused with the Vesc-project (opensource controllers)?

I was referring to the programmable settings in the PI800 software relating to the Golden Motor Vector controllers (VEC200, VEC300 and VEC500 etc.) :

I have similar issues with MP2 (ebike hubmotor), I can run it in reverse. But if I touch that button while running forwards, I haveto come to complete stop, before going in ether direction. (had to change the parameter for regen-break to 80%, because my 36v battery became overloaded, -so thats not the solution)

The original version of the PD-280 programming software for the non-vector Magic Pie controllers had an option to select "Immed" or "Unimm" for the reverse mode:



However, I am unable to try this function out as I don't have the Reverse wires connected on any of my Magic/Smart Pies and this software does not work with the MP4 and MP5 vector controllers.

I presume that the "Unimm"  option will only allow Reverse to be activated after the wheel has stopped turning in the forwards direction, whereas the "Immed" option would presumably select Reverse Immediately without waiting for the wheel to stop.

I did however post a very poor quality video on YouTube over eleven years ago demonstrating the basic operation of the reverse function on my MPIII motor, but at that time I didn't have a programming cable suitable for the MPIII to try out the different Reverse modes. Unfortunately, the USB programming cable I had for the Original Magic Pie and later MPII did not fit the connector on the MPIII's newer style harness.

The Miromax version of the PD-280 software also allowed the motor direction to be changed, the Reverse Sound to be turned On or Off, and the Regenerative braking could be set right up to 116% instead of 100%:



The reverse sound only worked on later MPI & MPII internal controllers equipped with a beeper and some BAC-281P external controllers.

Alan
 

[Pontus]

Although it might be possible with such a braking arrangement, it's not a path I'm willing to go. It ads complexity and several more points of failure.

If GM is right in their answer, which is not 100% clear due to both things getting lost in translation and the fact that they of course would like to sell me a new controller - then it's a fault by design.
The answer I was hoping for would be a firmware update, since all this is software settings inside the controller.

If not possible, my best hope is a refund for the current controller and buy a new one.

But I'm still curious if no one else have had this problem! Throwing forward & reverse is more or less standard procedure in harbour manoeuvres. Am I the only one with this experience? What's setting my installation apart from others?

[Sventropy]

Pontus, I haven’t had that exact problem. In fact sometimes, I put it in reverse while sailing to stop the prop from rotating because the noise can be annoying. Though I have had an issue at times with it not starting. I can’t quite isolate the situation that causes it. Sometimes after I’ve been motoring hard and stop for a second (to drop fenders or something before making the turn into my marina) it won’t restart for a minute. And sometimes when it’s auto-rotating really fast it won’t restart for a moment, then suddenly start up at whatever speed I’ve left the throttle in. This last bit has happened a couple times while fighting the current to sail under a bridge. Not fun.

I’ve wondered if heat has been an issue. When you stop the air cooled motor is no longer cooling so the temperature might peak then take a second to cool down. Though this only explains the first scenario and not the second.

Have you made any improvements?

Also I haven’t really been able to get the regeneration to work.

[BjornO]

Hi, I have the same problem when going from forward to reverse.
The first version of the speed control box was just a potentiometer. However, it became more unstable during the summer.
The second version had a multi-position rotary switch, and a separate switch to the brake input on the controller. It worked better, but as I also changed a lot of controller parameters, I don’t know why.
I an currently planning version 3 of the speed control box. This time I will put a switch on the throttle lever that automatically engages the brake signal when the lever is in its neutral position.
/Björn

[Fabio]

hi, I had the same problem and I changed the regenerative bracking option and now I can start the motor forward or reverse also if the propeller is turning in the other side, i'm still testing to real understand how it work.