potentiometer throttle causing VEC300 damage?

[Jusp]

The PI-800 app has an option 'potentiometer throttle' as speed throttle setting, and the green cable on the throttle connector plug is marked as 0-5V, and the PI-800 app sets 'throttle voltage protections'.

As a reasonably informed technical guy I concluded from this that we can hook up a potentiometer, as follows: the red and black cables go to the fixed 'ends' of the pot meter, while the green cable goes to the variable pole of the pot meter. This uses the pot meter as a voltage divider, giving (depending on the pot meter setting) a 0 to 5V input to the green cable.  As far as electronics is concerned, I expect a ADC (analog to digital converter) inside the VEC300, on the 'other' side of the green cable, converting the measured voltage into a motor speed. I used a 10k pot meter, but because an ADC would measure voltage the exact value of the pot meter should be pretty irrelevant, and this wiring should be safe.

This appears to work, but my question to this forum is whether this is a reasonable assumption, and whether this approach would be able to cause any damage to the VEC300.

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As background to this question: I have tested this solution, and this appeared to work fine. I cruised my boat through the harbor with it.
However, I then hooked up the PI-800 for the first time, and hit the 'default settings' button in the app. This erroneously loaded 72V settings on my 48V motor, that is, it blatantly assumed a different motor, and from that moment I haven't been able to use my motor. The controller 'beeped' undocumented error codes. Contacting Goldenmotor, they concluded from these codes that the controller was damaged. And after they heard that I hooked up a pot meter they clammed up and put all the blame on me.

Now I would not have any problem with taking responsibility for my assumptions, but on the other hand, it would take extremely fragile electronics to damage controller inputs this way, and given what I have seen the PI-800 app doing, I would find it more likely that the app caused the damage.

What is the opinion on this forum?

[Bikemad]

Hi Juul,

I cannot see how a 10K potentiometer could possibly damage the controller, as the maximum voltage would only be 5V and the minimum voltage would be 0V.

I have often used 10K potentiometers or trimpots for testing controllers on numerous GM hubmotors:





The low voltage protection might be triggered on some controllers if the throttle signal voltage is below ~0.8V, but this should in no way cause physical or lasting damage to the controller.

Placing a 3K resistor inline with the Black ground wire and a 2K resistor inline with the +5V Red wire should give a variable voltage output from the potentiometer of between 1V and 4.34V, which is not that dissimilar to a typical Hall sensor throttle output.

I also think it very unlikely that the programming software would damage the controller, as it typically will only allow parameters to be entered that are safe for the controller to accept.

I suspect there may well be something that is still slightly wrong with your settings, which is hopefully why your motor is currently not working.



For Example, if you have selected "parabola" for the Throttle mode selection (used with a "Forward - Neutral - Reverse" type boat throttle) the controller waits for a throttle signal voltage of ~2.5V when it is first powered up before it will allow the motor to work.

When you restore the default settings into the controller, it does not take into account what battery voltage, throttle or motor you have connected to it (or what type of vehicle it is being used in) therefore the relevant settings will always have to be adjusted to suit each particular installation.

Alan
 

[Jusp]

Hi Alan,

I found out over the weekend what the culprit was: simply setting the throttle type in my settings to 'potentiometer throttle' causes the controller to emit an undocumented error code that the Goldenmotor people interpreted as internal controller damage that needed me sending in the controller, "entirely at my own cost " (up to $400). Setting it back to HAL effect throttle appeared to magically repair the internal damage and everything worked as before (saving me the $400). Everything is working fine now. I am now using a potentiometer with HALL effect as setting, but hey, all the controller input is really interested in is a voltage

Thanks,

Juul

[Bikemad]

I'm pleased to hear that you've manage to sort it, looks like I should be able to uncross my fingers now. 

Alan