Scotty B says it can't be done

[benrocks]

So here is the back ground- 2002 EZ-GO TXT, XCT500PDS, with super solenoid, 36 Volt 2-GA cables, D&D 502.1 sepex motor. 18x9.50 tires on stock EZ-GO Rims, with a 3” lift kit.

I use this cart on my family farm in East Texas. We raise registered black Angus seed stock bulls. The terrain on our farm is mostly rolling hills and hay meadows. We have a few creek crossings that are relatively steep and somewhat slick but nothing I would consider over the top as far as severe off road. Each day we feed our bulls corn with a single axle 8’ trailer with an electric cake feeder which is attached to the top of the trailer. The whole rig fully loaded I’m guessing weighs close to 3,000 lbs. The one-mile feed trip each day from the barn to the feed lot is on an asphalt paved road and is virtually flat except for one short dip, and a gradual incline one way.
So now you know the back ground, here is the problem. We have been making this feed run with a much older EZ-GO Marathon resister cart for years without any problems. The bone stock Marathon cart also running on the same size tires and rims as the TXT pulling the same load. I built the TXT because I was afraid the Marathon would crap out eventually. But it seems the TXT cart can’t handle the load. Twice now in less than 2 months I have managed to overheat the D&D motor to the point that it has stopped running and smoke fumes out of the casing. These cases only occur when pulling the feed trailer. I am on the second motor now in 30 days and this event has occurred again. The motor still appears to work after it has time to cool down, but what gives? Why does the older cart handle the trip and this cart cannot??

Tonight I cracked open the motor to inspect. Attached are photos of the motor after it got hot and smoked out. The motor still appears to operate normally after it cooled down. So I am trying to determine if I have permanently damaged the motor or if it is going to be ok. What kind of motor and drive system do I need to build to handle what I am trying to do with this cart? Scotty B says it can’t be done, but the old marathon cart has been pulling this same load for years.

[teecro]

Pretty easy I think... Scotty is right!

Old cart has a series motor while they were slower they were stronger. Newer cart has a sepex motor while the are faster they are no where near as strong. If you really want a WORK cart your going to need 48 volt series motor...

[kab69440]

My guess would be that the Marathon is geared steeper than the TXT. I used to pull big loads with my Medalist, but there's a big difference in moving 60 feet from one railcar to the next and dragging that same load over a mile and up a hill. Honestly that is a whole lot of work for a golf cart and a pickup truck or small tractor might be better suited to the purpose.

if scotty say it can't be done i would believe him
as for the older cart handling the load it is the motor with torque that is the key
the sepex motor is not designed to handle the load you are trying to give it
i think if you had gone with a Series motor you would have no problems
i would redo the older cart

[Clemsoncartguy]

Like they said it has a series motor. All I know is what those these guys say. But seriously why tow that load with a golf cart? Buy an old Suzuki Sami or an old toyotaa truck or any older truck for that mater. Why punish a cart....why not use a tractor? I mean you can't be going 8mph up this small hill wiTh the cart...wouldn't you like to go a bit faster on the road just so you can have more time for other chores or sitting around?

Scotty knows his stuff. He never said it couldn't be done. Probably that with the new cart it can't or shouldnt.

[Revolution]

I am not sure how the resistor cart managed to pull 3,000 pounds a mile every day for years.

At least it had a series motor, as mentioned above. Series motors are better grunt work motors.

I have a bit of experience pulling heavy stuff with golf carts. I have pulled my tractor with my big cart three times now. The tractor weighs about 5,000 pounds with the front end loader, shredder and weights. I had to pull it half a mile to my workshop. My half ton chevy 2 wheel drive didn't have the traction to pull it.

My big cart has two 36 volt D&D torque motors running at 72 volts through two Alltrax 72volt 450 amp controllers. Its 4 wheel drive, one motor at the front and one motor at the rear.

My big cart pulled it without any damage but I wouldn't want to do it if I didn't have too. Both motors got pretty warm and the controllers were hot. I never pushed it past 5 mph while towing the tractor.

Theres no way my cart could survive long pulling my tractor 1 mile every day, even on pavement. So trying to pull 3,000 pounds with a single motor cart every day sounds like a serious challenge. I am still wondering how the old toaster cart did it.

[Volt_Ampere]

That does not look like a series motor to me. Those field coils look like sepex to me. You don't show the most critical part of the motor in those pix - the commutator. That is the part where the brushes contact and that is where the damage often happens when you overheat the motor.

[teecro]

Originally Posted by Volt_Ampere

That does not look like a series motor to me. Those field coils look like sepex to me. You don't show the most critical part of the motor in those pix - the commutator. That is the part where the brushes contact and that is where the damage often happens when you overheat the motor.

"So here is the back ground- 2002 EZ-GO TXT, XCT500PDS, with super solenoid, 36 Volt 2-GA cables, D&D 502.1 sepex motor. 18x9.50 tires on stock EZ-GO Rims, with a 3” lift kit."

[JohnnieB]

TXT is a body style and TXT's came with either a Series Drive or a SepEx drive (PDS) in model year 2002.

What you have is a 2002-TXT-PDS, which is better suited for neighborhood cruising than towing a 3000 pound trailer.

Can it be done? Obviously not with the setup you have or the motor(s) wouldn't have burnt out.

What can be done?

The trailer's rolling resistance is a major problem and there are factors other than weight the determine the rolling resistance. Are the trailer tires inflated to the maximum allowable pressure? Have the trailer's wheel bearings replaced recently?

Also, does the cart itself have excessive rolling resistance? Dragging brake shoes, wheel bearing issues, when was the differential oil last charged, what is the max inflation pressure of the cart's tires and what are they inflated to?

SepEx motors do not like to operate at low RPM, at what speed do you pull the trailer? I suspect you tow it at less than 8 MPH, which is only about 1850 RPM with 18" tires and 12.44:1 gears, so the motor is capable of drawing a lot of amps and the efficiency is low, so a lot of heat is produced.

Changing the differential gears to 14.92:1 would increase the torque by 19.9% and up the RPM from 1830 RPM at 8 MPH to 2230 RPM, more than halving the motor's max amp draw and upping its efficiency by several percent.

Since your cart is lifted, a two speed rear axle can be installed. 20:1 gears for towing the trailer and 10:1 gears for cruising the countryside.

Also, upping the pack voltage to 42V or 48V will keep motor temperature down.

In a nutshell, if it can be done, it ain't gonna be cheap.

[Clemsoncartguy]

Originally Posted by Volt_Ampere

That does not look like a series motor to me. Those field coils look like sepex to me. You don't show the most critical part of the motor in those pix - the commutator. That is the part where the brushes contact and that is where the damage often happens when you overheat the motor.

It is. The one he smoked is a sepex. The old cart "that's pulls it fine " is a series.