2013 Electric RXV Intermittent Braking - Stopping

[jamesnow73]

Here's my problem.
My cart will instantly and intermittently brake hard without notice. Makes the cart jerk back and forth. On three occasions the cart instantly braked to a complete stop. Once stopped it wouldn't go forward or reverse until the on/off switch was turned off then back on again.

Every time the cart brakes and jerks back and forth it feels like the motor/brake assembly is going to crash and burn! Not Good!

I put in a whole new set of batteries this past fall. 48V system. It was doing the braking thing prior to new batteries and still persists.

Thank you!
jamesnow73

[BobBoyce]

Originally Posted by jamesnow73

Here's my problem.
My cart will instantly and intermittently brake hard without notice. Makes the cart jerk back and forth. On three occasions the cart instantly braked to a complete stop. Once stopped it wouldn't go forward or reverse until the on/off switch was turned off then back on again.

Every time the cart brakes and jerks back and forth it feels like the motor/brake assembly is going to crash and burn! Not Good!

I put in a whole new set of batteries this past fall. 48V system. It was doing the braking thing prior to new batteries and still persists.

Thank you!
jamesnow73

Classic symptom of speed gears and/or way oversized tires on an RXV. The controller has factory calibrated motor maps for tires up to 20.5" with the stock 16.99:1 rear end gears.

[jamesnow73]

Thank you for the input Bob.
I purchased the cart 3 years ago as "refurbished." Had low profile type tires installed at purchase. Had them removed because they were very rough riding and beating up the front end suspension. Ended up changing out the front shocks and all bushings.

Current tires on the cart now are 215/50/12.

The cart didn't show this gearing/breaking problem until about 1 1/2 years after purchase.

Any other guidance as to what I should do or have done to fix the problem?

Thanks!
James.

[cgtech]

I'm betting on encoder problems, or corrosion in the harness going to encoder.

I bet the jerking is very violent, right?

[jamesnow73]

Yes, the jerking of the cart is quite violent. Freaks me out !!

[jamesnow73]

Good day cgtech. Thank you for the input.
I could use a small bit of guidance regarding the encoder.
Where is it located? Do you have readily available a schematic diagram showing it's location?
Thanks!

[usgicollector]

This is what it looks like and its located on the motor.

[kernal]

Originally Posted by jamesnow73

Good day cgtech. Thank you for the input.
I could use a small bit of guidance regarding the encoder.
Where is it located? Do you have readily available a schematic diagram showing it's location?
Thanks!

Youtube might be your friend.

[jamesnow73]

Originally Posted by usgicollector

This is what it looks like and its located on the motor.

A big "THANKYOU" to CGTech, usgicollector, kernal and everyone on this thread that helped me solve my intermittent braking problem. As an ex-farm boy with a degree in electronics engineering I enjoy learning how things work and "fixing them." I pulled the encoder from the motor to find a very small amount of fine metal shavings clinging to the encoder electromagnet. I cleaned it up, re-installed the encoder and the problem was solved. :) Also ordered a new encoder so I will now replace the original encoder with the new one and keep the original as a backup. I will keep a diligent watch on any new fine metal shavings - they came from somewhere. Thank you again, you guys are great!

[cgtech]

Glad a clean-up solved your problem. The 4 wires that go into the encoder are tiny little ones & often break inside where they cant be easily fixed, a problem exasperated by the harness being stretched too tight & not allowing enough flex for the sensor wires. Problem is, relax the harness to allow more flex for sensor wires & the harness sits in "prime battery acid damage zone", tie the harness up higher, away from acid, and the sensor wires suffer abuse. Hard to win that one.

As far as your particular case, your encoder is nearly identical to many automotive anti-lock brake wheel speed sensors, and I cant even tell you how many ABS lights I've cleared just by cleaning the junk off the end of the sensors.