ezgo starts to slow?

[quailwood_shop]

i have a 02 EZGO txt (dcs) i just built this cart from ground up / new batteries / new cables to everything / motor was sent out and rebuilt / forward and reverse switch is new / added lights and stereo using a madjax reducer / all new wiring to everything/ 8:1 high speed rear end / speed chip / high speed magnet in the motor for speed sensor / cart has been lowered 3 inches and is setting on 12" rims low pro tires / light bar in the front and custom lights in the back / madjax's plug and play wiring harness for lights / installed alt fuse panel for lights and radio . still running stock Curtis controller and solenoid.

PROBLEM:
on the maiden voyage the cart ran for maybe 30 min at full power and then all of the sudden the power cut in half . checked voltage while driving and there doesn't appear to be a major draw on the batteries it seems like it still runs good and everything is still working / lights / radio / all the cables stay cool even under a load and the batteries charge fine ?. I'm stumped please help

[scottyb]

My first impression with any cart that suddenly looses speed is it sounds like a motor problem.
What motor and control are you using?

[quailwood_shop]

Curtis pmc controller part # 73326g06 (stock)with run/tow switch and the stock motor . also the cart is 36 volts
the motor was completely rebuilt by turbo and electric

[quailwood_shop]

the cart

[JohnnieB]

A 2002 with a SepEx drive would be a PDS rather than a DCS. Also, having a "Speed Chip" indicates a PDS.

Since you have a stock PDS controller and 8:1 gears, I suspect the controller is going into the over temperature reduced performance mode.

Put controller into diagnostic mode and listen for the beep code when it looses performance. (Text at bottom of attached label tells you how to get into diagnostic mode)

Replace stock controller and solenoid with an Alltrax XCT48500 or larger and a MZJ400 solenoid, and up the pack voltage to 42V or 48V. You also might have to go to a high torque motor to run 8:1 gears.

What is the measured tire height?

[quailwood_shop]

tires are 215/35/12.
yikes ... ill try the diag mode soon and let you know what happens ...
thank you for taking the time

[JohnnieB]

A 215/35/12 tire translates to 17.925" tall and 8.465" wide, so it is roughly stock height (18") and width (8.5"). Of course, the size stamped on the sidewall is only approximate and may vary by an inch or more in either direction, so you have to physically measure them to know for sure.

With 17.925" tall tires and 8:1 gears, you have a theoretical 36% increase in top speed with an actual 35% loss in torque where rubber meets road. A stock PDS controller in the freedom mode (speed chip installed) limits the motor to about 4400 RPM (with stock speed magnet installed) which is 29.33 MPH, but your cart won't reach that speed because the 35% torque loss is throughout the motor's RPM spectrum.

The magnet disk with fewer pairs of poles, does allow the motor to spin faster than 4400 RPM with a stock PDS controller, but as mentioned above, your motor won't reach 4400 RPM (at 36V).

With 48V, which a stock PDS controller cannot handle and a controller that allowed to motor to spin at 6000RPM, you cart would do about 40 MPH.

[quailwood_shop]

so if I decide to upgrade to the alltrax xct48500 and the mzj400 solenoid as you recommended will I need to up battery voltage for those components ,or can those components still run off the 36 v that I have , and should I try the controller and solenoid before upgrading to the high torque motor or just assume it needs replaced as well ?.
and would I need to upgrade f&r switch or any other electrical parts with the upgrades .

and again THANK YOU SO MUCH FOR THE HELP

[scottyb]

You Are going to need the controller/solenoid upgrade with the 8:1 gears. The components Johnnie suggested will run on 36 - 48v. 42 volts (7/6v batteries) is the sweet spot voltage-wise for the stock motor. The Aftermarket motors will all do well on 48v. You do not need to upgrade the F&R switch on this cart but 2 gauge cables throughout the system will help with performance once more amperage is allowed to flow.

[quailwood_shop]

you guys are awesome and the help is very much appreciated .