Cable Upgrade - TXT 48V

[geoffarias]

Originally Posted by JohnnieB

1. I use GPS as well as motor RPM. Phone GPS apps and dedicated GPS receivers are both reasonably accurate since the displayed speed is a sliding window average of several of several instantaneous speed calculations based on distance moved over elapsed time of move.

Since I know my tire's dynamic radius and the gear ratio of my differential and my Alltrax XCT controller provides motor RPM data in real time with a laptop connected top it and data logs can be stored for later review, I can calculate my cart's speed from the motor RPM. For example 6503RPM = 26.5MPH. since my gears are 12.44:1 and my tires are effectively 17.0395260947761" tall when rolling.

2. Something is holding your cart back. It ought to be doing 22MPH or so.

3. Several things can cause a cart to run slower than theoretical speed. A few of them are:

Any and all resistances in the cables/connections/contacts that deliver the electrical energy to the motor drop the amount of voltage that can be applied to the armature and the max motor RPM at any given mechanical loading is determined by the voltage applied. For sepex motors, like you and I have, field amps also influence max RPM, but if field amps are kept the same, armature voltage is the determining factor.

My cart was 3 years old when I got it and the cables looked okay to my trained eye (I've been repairing electronic and electromechanical stuff since the late 1950's), but appeared to be a mix of 6Ga and 4Ga, so I replaced them all with 2Ga. I had access to a meter that has Kelvin Clips and accurately measures low Ohmic values, so I measured my new cables. The longest 2Ga cables had 0.0005Ω including the ring terminals that were silver soldered on. That is more or less the intrinsic resistance of the materials involved. When I later measured the OEM cables I removed, some of the had up to 0.010Ω. Not much, but I did get a noticeable improvement in low end torque. No change in top speed due to the RPM being limited by stock controller.

The tire size stamped on sidewall is approximate. My tires are stamped 18x8.5-8 and are only 17" tall. Measuring the tire height with a yardstick and level will be pretty close, but to get a really accurate number, measure how far the cart moves with 10 rotations of tires. That will give you the rolling circumstance X10 and the diameter can be calculated from the

Throttle might not be reaching 100%.

Battery pack voltage might be dropping excessive under load.

Low pressure type tires.

Underinflated tires.

Dragging brakes.

Stiff bearings.

...

See what happen with the new cables and we'll go from there, Bob may have some suggestions also. He's probably forgotten more than I'll ever know about this stuff.

All great suggestions and what I was looking for heading into the weekend. Ill pop on those new cables tonight when I get home and see whats going on. From there, Ill check the brakes (tire pressure was checked when I originally got cart and it was only doing 17 MPH with bad batteries. My father in law has a FLUKE meter since he is a marine electrician and so I will def measure a before and after on the cables resistance.

My guess based on research and input is that Ill notice more pep off the line but not much gain in top speed.

I recently had a hub spin out on me. I ordered two hubs but only replaced the bad one since I was short on time the day I dove into the project. Any chance Im losing speed due to the other hub? I checked the pin/nut on both wheels and only the one was spinning.

Lastly, if throttle is not reaching 100% how do I adjust or address that?

[yurtle]

ITS adjustment is in the manual in the Stickies.

[JohnnieB]

Originally Posted by geoffarias

All great suggestions and what I was looking for heading into the weekend. Ill pop on those new cables tonight when I get home and see whats going on. From there, Ill check the brakes (tire pressure was checked when I originally got cart and it was only doing 17 MPH with bad batteries. My father in law has a FLUKE meter since he is a marine electrician and so I will def measure a before and after on the cables resistance.

My guess based on research and input is that Ill notice more pep off the line but not much gain in top speed.

I recently had a hub spin out on me. I ordered two hubs but only replaced the bad one since I was short on time the day I dove into the project. Any chance Im losing speed due to the other hub? I checked the pin/nut on both wheels and only the one was spinning.

Lastly, if throttle is not reaching 100% how do I adjust or address that?

A handheld DMM, even one made by Fluke, usually isn't very accurate on the Ohm function when measuring very low Ohms. If the old cables are really bad, and they might be, it may show an Ohmic reading, otherwise it'll probably read all 0's. The instrument I used is designed to measure the resistance in grounds between medical devices and the medical facility's AC distribution system and accurately resolves to less than a Milli-ohm.

Measuring the voltage drop across a cable can be used to compare Ohmic values and if Amps is known, Ohms can be calculated.

If your F-i-L's meter has a Min/Max function, connect it between the controller's B- terminal and the solenoid's battery side large terminal. That measures the battery pack voltage as close to the controller as possible without being switched on and off. Find a gentle incline and starting from a standstill at the bottom, drive up it at full throttle with meter attached. Note the lowest voltage recorded. Repeat after new cables are installed and compare the two lowest voltage reached on same hill under same conditions.

Another test is the connect the Fluke DVM in Min/Max mode between the A1 and A2 terminals on motor and measure the max voltage reached while traveling at top speed on level pavement. This is also a good test for throttle reaching 100%. (Max voltage between controller's B- and B+ terminals should match Max voltage between A1 and A2 when throttle is at 100%)

Attached is a service manual for a TX-48. ITS adjustments and ITS voltages are on pages E-10, E-11 and E-12.

[geoffarias]

Not a whole lot of great news. I swapped the cables and no noticeable difference. I only found 10 high voltage cables in my 2013 TXT 48V. 5 between batteries, 2 at main positive and negative to battery bank, one between controller and solenoid, and 2 from controller to motor. Can anyone confirm that I got them all?

I did open the ITS. The gap was rather large and I put in a 7/32 allen wrench in there (since thats what I thought I had read the spacing should be between plunger and ITS. Im just sitting down to computer and realizing its 17/64. so Im 3/64 of an inch off of where it should be. Not sure if that makes ANY difference in top speed or acceleration, but Ill reopen it tomorrow and adjust again. Ill also run the cart again with full batteries as they were probably 70% full when testing since we had run around earlier in the evening.

The fluke measured the new cables at .2 OHM. Ill take the cables I took off cart to FIL tomorrow and test them and see if there is any difference measurable by the Fluke.

Thanks to everyone for the input. IF any has any other suggestions of what could be leading to the less than expected top end, Id appreciate it. Tires are measured from floor to top of tread at 22.5" roughly (stamped as 23" tires") on a 2013 TXT 48V with brand new trojans and has been programmed by Bob Boyce to go faster (he recommended I swap cables when I didn't get more top end during his visit). At this point, I may have to give Bob a ring and see if he can pull up the log from my programming and see if he sees anything odd.

Im stumped.

[Doubles Shooter]

You got all the HV cables. There are 10 on the TXT. However, that is the end of my help. I'm lost from here. Good luck.

[JohnnieB]

Originally Posted by geoffarias

1. Not a whole lot of great news. I swapped the cables and no noticeable difference. I only found 10 high voltage cables in my 2013 TXT 48V. 5 between batteries, 2 at main positive and negative to battery bank, one between controller and solenoid, and 2 from controller to motor. Can anyone confirm that I got them all?

2. I did open the ITS. The gap was rather large and I put in a 7/32 allen wrench in there (since thats what I thought I had read the spacing should be between plunger and ITS. Im just sitting down to computer and realizing its 17/64. so Im 3/64 of an inch off of where it should be. Not sure if that makes ANY difference in top speed or acceleration, but Ill reopen it tomorrow and adjust again. Ill also run the cart again with full batteries as they were probably 70% full when testing since we had run around earlier in the evening.

3. The fluke measured the new cables at .2 OHM. Ill take the cables I took off cart to FIL tomorrow and test them and see if there is any difference measurable by the Fluke.

4. Thanks to everyone for the input. IF any has any other suggestions of what could be leading to the less than expected top end, Id appreciate it.

5. Tires are measured from floor to top of tread at 22.5" roughly (stamped as 23" tires") on a 2013 TXT 48V with brand new trojans and has been programmed by Bob Boyce to go faster (he recommended I swap cables when I didn't get more top end during his visit). At this point, I may have to give Bob a ring and see if he can pull up the log from my programming and see if he sees anything odd.

Im stumped.

1. Apparently you received a cable kit for a series drive cart. However there is no difference in the cables themselves and you did replace all ten of the high current cables in your sepex drive.

2. The pedal up spacing is to provide some dead space at the beginning of the pedal's travel so cart doesn't jump when trying to start slowly. Basically, the pedal ought to move a little bit before the solenoid clicks.

!!!!! While you have the pedal box open, measure the voltage between B- at battery pack and the terminal on the ITS sensor that has the black wire on it. You should read between 0.7V and 1.3V when the pedal is pushed just far enough to make solenoid click and between 2.2V and 3.2V when pedal is pushed all the way down. Then measure the ITS voltage at the controller (Black wire goes to Pin-2 -- bottom row second from right).

If the pedal down voltage is less than 2.2V at the controller, the output will be less than 100% and cart won't reach it max speed.

3. Is that the reading of all 10 cables connected in series, or just one of the cable? In either case 0.2Ω is absolutely terrible for new cables.

A 48V Sepex drive has about 18' of cable and the conductors, in and of themselves, in 18' of 2Ga cable has 0.0028134Ω of resistance. The ring terminals and the cable/ring terminal interface will add some additional resistance, but not two orders of magnitude.

FWIW: The longest individual cable in my 2Ga set had 0.0005Ω of resistance including ring terminals when new.

4. I listed several inn earlier post.

5. With 22.5" tall tires, the theoretical top speed is still above 23MPH.

[geoffarias]

Originally Posted by JohnnieB

1. Apparently you received a cable kit for a series drive cart. However there is no difference in the cables themselves and you did replace all ten of the high current cables in your sepex drive.

2. The pedal up spacing is to provide some dead space at the beginning of the pedal's travel so cart doesn't jump when trying to start slowly. Basically, the pedal ought to move a little bit before the solenoid clicks.

!!!!! While you have the pedal box open, measure the voltage between B- at battery pack and the terminal on the ITS sensor that has the black wire on it. You should read between 0.7V and 1.3V when the pedal is pushed just far enough to make solenoid click and between 2.2V and 3.2V when pedal is pushed all the way down. Then measure the ITS voltage at the controller (Black wire goes to Pin-2 -- bottom row second from right).


If the pedal down voltage is less than 2.2V at the controller, the output will be less than 100% and cart won't reach it max speed.

3. Is that the reading of all 10 cables connected in series, or just one of the cable? In either case 0.2Ω is absolutely terrible for new cables.

A 48V Sepex drive has about 18' of cable and the conductors, in and of themselves, in 18' of 2Ga cable has 0.0028134Ω of resistance. The ring terminals and the cable/ring terminal interface will add some additional resistance, but not two orders of magnitude.

FWIW: The longest individual cable in my 2Ga set had 0.0005Ω of resistance including ring terminals when new.

4. I listed several inn earlier post.

5. With 22.5" tall tires, the theoretical top speed is still above 23MPH.

The fluke isn’t a great measured of ohm. The reading was the same on the new cables as when you connect the two test leads together. I’ll dig into it more today.

My next test is to voltage test the ITS. If that checks out I’ll
Probably put a call into Bob and see if he can review his log as I know he saved it when he did it