Motor/wheels lock up coasting downhill

tomgoldie

I have 2005 EZGO TXT PDS with a freedom plug, and after adding some downhill stretches to my daily run, have identified the following issue:

When coasting downhill with foot off the accelerator, I will often hear PDS solenoid click off, then a fraction of a second after a slight hesitation, the back wheels lock up and I skid to a stop. It can happen at any speed but does not always happen - and if I depress the accelerator slightly it does seem to cut down on it happening. It NEVER happens when going downhill with accelerator depressed.

Any suggestions as to cause and solution? I'd just race downhill, but as I have a dog on a leash running beside me, I don't want to drag him. I have MS, so excercising him on foot would not be a suggestion that helps much.
.

Thanks in advance!

BGW

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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.

kgsc

I would think controller failure or someone has changed some wires around and cart is losing its activation circuit.

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

gornoman

RXV roll away protection only occurs after the cart has stopped, and accelerator pedal HAS NOT been pressed.

kgsc

But this is a 2005 TXT PDS.. But does bring up the question, are you hearing beeping when this happens ?

gornoman

My bad, I was sitting in an RXV when I typed that. Roll away protection is the same protocol in a TXT PDS.

kgsc

So you had RXV on the brain ?

rib33024

Well I guess that's not the problem

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 .