Cables are hot, forward good, reverse stutter

dman19709

Having issues with EZGO 1996 36v DCS.
Totally rebuilt from frame up. Lot of $$ invested in body.
23" tires with second seating.
New batteries fully charged.
Original motor was extremely hot with lose terminals, replaced with 2500 fleet.
1206sx controller, 10 pin

Problem:
1. 6 awg cable from solenoid to controller super hot.
2. Goes forward but stutters in reverse.

Replaced:
1. Replaced controller and solenoid
Results: same problem

Took it to repair place, they replaced motor, controller, solenoid, fixed some wiring issues, same results and they have no idea. They put back all the original items.

Replaced:
1. 2 AWG w/soldered lugs from main battery post to solenoid, to controller to motor.
Results: same problem

Observation: On motor, the A1 is across from S2??? and comparing to others the A1 is pictured across from S1.
Would this be the problem? And should I switch A1 to A2? Then I would have to switch S1 and S2 too?

Any ideas on problem?

BGW

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Timberwolflt

6awg needs to go immediately... the experts should be here soon

JohnnieB

AS long as the heavy cables go to the A1/A2 studs on motor and the thinner gauge cables go to the S1/S2 studs and the cart goes forward when F/R is in the forward position, the motor is wired correctly.

The 23" tall tires take at least 28% more torque from the motor to move the same weight at the same speed as stock height (18") tires do. If the 23" tires are low pressure types, (<10PSI max inflation pressure), even more torque is needed.

With 23" tall tires and a rear seat, a minimum of 4Ga high current cables are needed throughout. There is a total of ten high current cables in a DCS drive. 2Ga throughout would be better.

Selecting reverse automatically reduces the amps (Amps = Torque) to motor by half, so that may be the reason for the stuttering. Try swapping the F1 and F2 cables at the controller (The thinner cables that connect to S1 & S2 on motor) and see if the cart now runs normal going backwards and stutters going forward, or if it still runs normally forward and stutters in reverse.

If the direction cart stutters in stays the same when F1/F2 are swapped, the problem is in the mechanical drive system (someplace after the motor), but I suspect the Curtis 120SX (stock DCS) controller lacks the oomph to turn the oversized tires at half power.


No matter what, the controller needs to be replaced with an Alltrax XCT48500-DCS (or larger) controller.

DaveTM

^^^^^--------And I was gonna say the same thing-----^^^^^^^

dman19709

I swap out the F1 & F2 and it now stuttered going forward. I swap them back.
I replaced the large back tires with stock. No more stutter.
Next problem. Since I tested this on flat grade and moved fast. I figured it was fixed. Wrong. Drove it down the side of my house and tried to go up slight grade and it died.
I tested the motor while trying to go up the hill. Giving it full peddle, the voltage on A1 & A2 on the motor was 8V. On the controller was also 8V.
Should this be higher?
I have no diodes are they needed?

JohnnieB

At 100% throttle the voltage between A1 & A2 ought to be the same as the voltage between the B- and B+ terminal on the controller, which in turn ought to be the same as the battery pack voltage.

You mentioned replacing some of the High current cables with 2Ga. All ten of the high current cables should be the same gauge, so if there are any old cables still in place, replace them.

If the problem still exists, check the battery pack voltage and individual battery voltages while driving up that hill where the voltage at the motor dropped to 8V.

Imapled

Heed JohnnieB's advice or your 1206SX controller will look like this:

Warped1206SX.jpg

On an interesting note... I just pulled a "rebuilt" FSIP controller out of a 1995 DCS cart and it says it is 300amp. I won't even sell the 1206SX controllers second hand as they have no speed sensor and overheat all the freaking time.

The alternative controller (groans from the audience as it isn't Alltrax product) is the Navitas TSX3.0 440 or 600. The nice thing about the wiring harness for DCS carts on that one is it has a spot for a speed sensor. So if you upgrade your motor you can get one with a speed sensor on it.

See: http://www.buggiesgonewild.com/elect...ml#post1607764

Cheers,
Impaled

dman19709

Battery Bank test sitting still = 38.5v
Battery Bank test up on blocks giving throttle = 37.9v
Battery bank test while driving.
Flat grade - started at 37.8v went to 35v still moved.
Slight grade - started at 37.8 went to 35.5v and cart stopped.
Reverse did the same.

Controller test sitting still
M-(A1) to B-(battery -) = 38.4v
M-(A1) to B+(A2)= 0v
B+(A2) to B-(battery -) = 38.3v

Controller test up on blocks giving throttle
M-(A1) to B-(battery -) = 38.2v and decreased
M-(A1) to B+(A2)= 1.4(solenoid click) up to 10v
B+(A2) to B-(battery -) = 34v and decreased quickly

Motor driving test sitting still = 0v
Motor test up on blocks giving throttle = 0 to 16v
Flat grade - 0 to 10V, still moved.
Start out on Slight grade - 0 to 8.2v cart didn't move,
Reverse did the same.
Driving test stopped, testing at this point wires from controller CB+ to A2 hot.

I tested all pins and all other connection and they met spec numbers.

I do don't claim to be a electrical expert and that's why I'm here. I do not understand volt - amps - current

Is this a bad controller? Only pushing out 10V max? Or motor not accepting it?

I'm trying to understand the problem so I know what to replace. I just need to know!!
I plan on alltrax500 and HD400 solenoid, Admiral B2 mtr if needed.

JohnnieB - Thanks again for your help. Could you send me the spec's on your hat, I need the additional brain power.

LabRat

some general info from the Golf Cart Mechanic field of dreams....
this week we had 4 TXT 36v come in that did not run, all were lifted with 22" being the smallest tire size, all had stock drive systems & OEM 6ga motor cables.
Dead motors on all 4 carts. 2 of these customers upgraded, One just wanted to get it running to sale, and the other wet himself when he saw the estimate. We do not provide any motor rebuild option to our customers.
the morale of the story is to follow the advice of the guys at BGW and you want have a little shop squirrel like me show you an $800 repair estimate just to get it running

JohnnieB

Volts are pressure pushing the electrons through wire, motors and stuff. Amps are the quantity of electrons passing a point. Current refers to the flowing of electrons.

A chemical reaction in the batteries produce both amps of electrons and the volts that push them. A stalled motor will try to draw all the amps the batteries can produce, the higher the voltage, the more amps drawn by motor. The faster the motor's armature spins, the fewer amps it is able to draw at the voltage being applied to it.

The controller limits the number of amps the motor can draw; And can only pass what is being supplied to it.

Your tests indicate the voltage between the controller's B- and B+ drops to 34V and less even though the tires are spinning in the air. That means either the battery pack's voltage is dropping abnormally low, or the voltage is being lost between the battery pack's main terminals and the controller.

Check what the battery pack voltage is dropping to when driving cart.

-----------
The ten high current cables need to be replaced with 4Ga or thicker cables.
The stock (85A rated) solenoid needs to be replaced with a 200A or higher solenoid.
The stock DCS motor is a good one, relatively high torque and good speed, so try running with it after above upgrades, a new motor may not be needed, but the stock DCS motor can most likely use a set of brushes, a new bearing and a thorough cleaning.


If the batteries are bad, it would be a good time to up the battery pack to 48V. That will give you 33% more torque, which more than offsets the torque loses of the 23" tires.