what controller to buy?

[outdoorsed]

Hi All
so here is the latest in my saga with this golf cart.
when i bought it it was a 9mph cart (stock 99 ezgo 954 36v) Over the last three years, I bought new 6 v batteries put on nicer tires and wheels that are maybe 1.5 inches taller then stock and then I bought a PQ Bandit motor. At this I got the cart (with two adults and 3 teen kids aprox 500 lbs) up to 13 MPH but not much torque. So if any of you had read my threads, you know that I've been wanting to get more out of the cart, so last Fall after talking to techs at buggies unlimited I decided to buy a curtis 500 amp controller. So last fall when I installed it my speed dropped to 9mph, I called b.u. back and the tech without running any tests determined it was a faulty controller and sent me a replacement. So this spring I upgraded to 2 ga wires and installed the new controller, and still 9mph at best. Trying to trouble shoot failed to find the problem, so I took the cart to a repair place. $300.00 later I had a new 200 amp solenoid and a cart that still only went maybe 9mph. Over two days of testing with the b.u.techs they decided that my problem was the I.T.S. switch so one hundred and something dollars later a new switch arrived on my door step. I installed the switch and again, 9mph at best (and by the way that's with just me on the cart) Frustration..... So I decided to put back in my old curtis 350 that the cart came with, and the cart took off back up to 13 MPH no problem and probably would have hit 14 mph if I had had more running room. Now b.u. swear that that controller was programmed for 36v. I have a hard time believing that and tomorrow I'm going to make arrangements to return it for a refund. I would still like to get more torque and a few more MPH. but I'm gun shy of curtis.
I am open to suggestions of where to go next.
Thank you

[mgray70]

It is hard to beat the Alltrax! You yourself can install software on your computer and check/change settings, monitor the ITS input, motor current, etc. You can troubleshoot it yourself and not have to rely on someone that wants to sell you more parts.

Sent from my SM-G930R4 using Tapatalk

[JohnnieB]

I wholeheartedly agree with mgray70.

Since it is a heavy cart, put an Alltrax SR48500 (or larger) Alltrax controller in it.

However, the amperage throughput of the controller translates into low end torque rather than top speed. Voltage applied to the motor translates to speed.

In a nutshell, your cart should run at the same top speed, with either the original Curtis 350A controller or the Curtis 500A replacement controller, or an Alltrax SR48500. The 13 MPH top speed you've seen is mostly a combination of cart weight, battery pack voltage, tire height, rear end gear ratio and motor type. The 500A Curtis on doing 9 MPH is most likely due to its output not reaching 100% duty cycle for some reason. At 100% duty cycle, the voltage applied to the motor is equal to the battery pack voltage and it appears that only about 70% of the battery pack voltage is being applied to the motor, so the cart is only doing 9MPH with the 500A controller.

Mathematically, the 19.5" tall tires should give you a 8.3% speed gain accompanied by a 7.7% torque loss, so on stock height tires the cart had a top speed of about 12MPH.

The PQ Bandit probably isn't the best choice of motors for your cart. Something with longer case that has 20% or 30% more torque than stock and has stock speed would have better performance.

The next time you replace the batteries, go to 48V and you'll get a 33% speed increase as well as a 33% torque increase.

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To check if a controller is going to 100% duty cycle, connect a DVM between the controller's B- and M- terminals. You should measure FULL repeat FULL battery pack voltage (38.2V when fully charged) when the pedal is pushed just far enough to make solenoid click and it should drop to ZERO VOLTS when pedal is on floor.

[outdoorsed]

Update:
So I returned my Curtis to Buggies Unlimited. The tech says he has reprogramed it. I'll be interested to see how it works.