Slow/sluggish response - upgrade controller?

Brianwhite81

I have a 2000 EZGO TXT 36V Series cart that I purchased last year. Backseat added, new tires on 10” wheels to replace stock. Replaced batteries last fall with the black box Trojan batteries.

Before replacing batteries cart had been driving slow at times on hills and slow to respond on throttle input. Old batteries had developed some leaks so I went ahead and replaced them. New batteries didn’t seem to have much affect on drivability.

It seems to happen worse during the day when the air temperature is warmer. When evening comes and it cools off, it seems to perform normally. I’ve tested voltages yesterday and everything seems to check out with solenoid and voltages at controller. Battery voltage is around 38.6V. When driving today it will come to normal top speed of this cart (12MPH on flat, 14-15 downhill, around 8-9 uphill) but it gets there slower than normal without the pull you normally feel when it’s running good. I ended up unhooking the 1/2 speed reverse yesterday because it got to where it wouldn’t even pull itself in reverse in the yard up a slight incline. Reverse works great now at full speed, you just have to be careful. It almost seems more responsive than forward.

Looking for advice from the group, does this sound like I need an upgraded controller to handle extra weight of backseat and passengers or is there another issue I should be looking at? I’d like to get a little more top end and torque out of this cart and better overall drivability for all conditions. If I upgrade controller, do I have to get a new motor too? How about F/R switch?

BGW

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yurtle

Try hooking your volt meter probes to the pack, either under the seat or in the charger port, then drive. Monitor voltage drop under load. If voltage drop is excessive, try measuring each battery one at a time while under load. You could have one bad one.

Try testing the throttle circuit with method posted below from the Stickies:

http://www.buggiesgonewild.com/elect...e-testing.html

As I mention there, there is a four wire Molex connector that can sometimes cause problems. Two wires are for the ITS - the throttle sensor - and two are for the throttle microswitch. You can unplug, spray contact cleaner, and repeatedly plug/unplug/plug and see if that helps. If it does, you may want to consider eliminating this plus and soldering or butt splicing the four wire pairs then covering with a good marine grade adhesive lined heat shrink. Moisture and/or corrosion in this connector can affect the throttle signal. It's located between the controller/solenoid, and the FNR - direction switch.

Attached Images

Molex.jpeg (254.5 KB, 0 views)

JohnnieB

The wheel diameter (10") only changes appearance, but the tire's diameter (tire height) has a major impact on performance. What is the height of your tires? (Stock height is 18")

A completely stock 2000 TXT with a series drive does about 14MPH on level pavement, so you cart is slower than stock for some reason(s).

Are any of the high current cables getting hot?

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To get more top speed and top end torque, the battery pack voltage needs to be increased, however replacing all 13 high current cables and installing a true HD F/R switch assembly (or reversing contactor) along with a 200A or greater solenoid and an Allltrax SR48400 (or larger) controller ought to give you something akin to stock performance with oversized tires and a rear seat powered by a 36V battery pack.

The motor might need brushes.

For more speed and better performance go to a 48V battery pack.

Brianwhite81

Thanks for the replies! I tried the molex connector cleaning and plug/unplug tonight, no change. Rode around for a bit tonight, cables are not warm to touch and controller heat sink is not hot either.

Next diagnostics I’ll do is the throttle test and load testing the batteries. I’ll respond back with those when I get a chance to get them done.

Thanks again!


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Brianwhite81

[QUOTE=JohnnieB;1621313]The wheel diameter (10") only changes appearance, but the tire's diameter (tire height) has a major impact on performance. What is the height of your tires? (Stock height is 18")




My tires are stock height. 18” tall tires on new 10” wheels.


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yurtle

One other thing to check would be to jack it up and see if the brakes are dragging.

Brianwhite81

Over the past few weeks, I’ve checked brakes, battery load, and throttle test. All seem normal.

Brakes are touching a little, cleaned everything up and adjusted tension and put back together but self adjust goes back to the way it was before.

Throttle test was normal. Battery test, only drops 2.5-3V on hills and full throttle take-off.

I do think I need to put in some new bearings and change rear oil but mechanically seems fine. Battery cables could probably stand to be upgraded (seems to be a mixed bag of what they had, most 4GA, could stand to be nicer cables).

I’m willing to put some money into this cart, what’s the best place to start on upgrades?


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scottyb

Go here and read this upgrade tutorial. Afterwards you will know more than most about what needs to be done and in what order. https://www.cartsunlimited.net/upgrade-suggestions.html

Brianwhite81

Thanks, great info! I’ve read through a lot of this over the past few days. I have considered doing the whole package (controller, switch, cables, and motor). Should I wait on the motor and just do controller, cables, and switch to start?



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