Motor/wheels lock up coasting downhill

[tomgoldie]

Originally Posted by JohnnieB

When going downhill with foot off pedal, regen braking is occurring and when the solenoid contacts open, the battery pack is no longer acting as a load for the motor, which is acting as a generator, and its voltage output skyrockets.

That drives the controller into a high battery voltage error, but I'm unsure what happens next. Since the rear tires lock up, the regen braking goes to max and either the solenoid contacts close again and the energy is sent to the battery pack, or the energy is dumped into the controller. Since the controller hasn't burnt out (yet), I suspect the solenoid is closing again, but the sound is masked by the sliding tires.

The original problem is the solenoid de-energizing when it shouldn't and I have no idea why that is happening, other than a bad controller. (Solenoid is controlled by controller in a PDS drive.)

Personally, I'd replace the stock PDS controller with an Alltrax XCT48400-PDS controller, which is user programmable.

I was under the impression that the freedom plug was used to disable regen braking.

I sent the controller off for repair once before (for a different issue), but it came back testing fine.

What would happen if the speed sensor were rotating a little? Come to think of it, it doesn't usually do it unless there is some bump or jostling of the cart - even braking can cause it. Could a long, unsupported speed sensor cable do that - I mean, twist a little and cause the controller to think it needs run-away protection?

[gornoman]

Originally Posted by tomgoldie

Well, and this answers another issue kgsc mentioned about losing power on the activation circuit, someone unknown to me in the past messed with some wiring - not sure if it was JUST to disable the backup alarm and beeper - but that has been the most obvious outcome of the alterations .

Loosing/regaining power in the solenoid activation circuit will cause the cart to behave as described. The keyswitch would be my first target.

[JohnnieB]

Originally Posted by tomgoldie

I was under the impression that the freedom plug was used to disable regen braking.

I sent the controller off for repair once before (for a different issue), but it came back testing fine.

What would happen if the speed sensor were rotating a little? Come to think of it, it doesn't usually do it unless there is some bump or jostling of the cart - even braking can cause it. Could a long, unsupported speed sensor cable do that - I mean, twist a little and cause the controller to think it needs run-away protection?

The freedom plug only keeps the controller from applying regen braking when slowing from speeds less than max speed for the Freedom mode (about 18MPH).

If the cart tries to exceed the max allowable speed (IE: going downhill) regen braking is still applied.

If cart is pushed or pull after sitting still for about a second, the regen braking is still applied.

If the F/R selector is changed while cart is moving, regen barking is still applied.

---------
Not happening unless a bump is hit or brakes applied, sounds like a loose connection or broken wire.

[tomgoldie]

Originally Posted by rib33024

It sound to me like the cart is doing what ezgo designed it to do. Roll Away. When the cart is sitting by it's self, (Which that is what the cart thinks is happen with out your foot on the go pedal) It's in roll Away mode, and the controller is stopping the cart like it was made to do . Maybe not just my two cent

This was my thought, too. I thought maybe speed sensor was twisting in its well under torque provided by long, floppy wire. I figured a short, quick rotation of the sensor matching the speed of magnets in motor might send controller a signal that the motor was no longer rotating (as if it were stopped) - thus activating roll-away protection

But I recently used long zip ties to secure the sensor lead to motor housing, and applied a few beads of permatex flexible assembly to the back of the sensor to tack it to the ends of the inner spring clip. But it's still exhibiting the same behavior.

[tomgoldie]

Originally Posted by JohnnieB

That is a new one on me, but I pretty sure what is happening up to a point.

When going downhill with foot off pedal, regen braking is occurring and when the solenoid contacts open, the battery pack is no longer acting as a load for the motor, which is acting as a generator, and its voltage output skyrockets.

That drives the controller into a high battery voltage error, but I'm unsure what happens next. Since the rear tires lock up, the regen braking goes to max and either the solenoid contacts close again and the energy is sent to the battery pack, or the energy is dumped into the controller. Since the controller hasn't burnt out (yet), I suspect the solenoid is closing again, but the sound is masked by the sliding tires.

The original problem is the solenoid de-energizing when it shouldn't and I have no idea why that is happening, other than a bad controller. (Solenoid is controlled by controller in a PDS drive.)

Personally, I'd replace the stock PDS controller with an Alltrax XCT48400-PDS controller, which is user programmable.

Using the batteries for resistance MIGHT be a problem. I have some lithium batteries that have circuit protection - e.g. they briefly shut down briefly when providing too much current. I wonder if they are doing that under regen and causing the activation circuit to de-energize - even though I'd think regen circuit voltage would suffice.

However, when batteries cut out briefly when I'm trying to make it go too fast uphill, it never causes the wheels to lock up - but then I have the accelerator pedal pressed, too.

[cgtech]

Originally Posted by tomgoldie

Using the batteries for resistance MIGHT be a problem. I have some lithium batteries that have circuit protection - e.g. they briefly shut down briefly when providing too much current. I wonder if they are doing that under regen and causing the activation circuit to de-energize - even though I'd think regen circuit voltage would suffice.

However, when batteries cut out briefly when I'm trying to make it go too fast uphill, it never causes the wheels to lock up - but then I have the accelerator pedal pressed, too.

This changes things significantly. You need to monitor voltage while going down hill to see how high it's going. And if it's hitting the max voltage cutout.

[tomgoldie]

Originally Posted by cgtech

This changes things significantly. You need to monitor voltage while going down hill to see how high it's going. And if it's hitting the max voltage cutout.

Monitoring voltage realtime - unless anyone knows of a cheap Bluetooth clip-on - might be more expensive than a 36v capacitor that I was thinking of installing to maintain activation circuit.

I'm just thinking here and new to this, so can you see any downside?