Speed issue - Tried Everything ! Seeking Advise

sthreatt

I am working with a 2016 EzGo TXT48, 1 yr old batteries, will only run 10 MPH. It is in Freedom Mode 5 and will run and show 19.5 MPH on jack stands. Will only run 10 MPH on road. Have replaced with new speed sensor and magnet, no help. Replaced new/rebuilt 1206HB-5201 controller, no change. Removed motor and probed A1 to A2, S1 to S2, all checked good and no continuity to motor case from either, no continuity from A to S . Disassembled motor and looked at brushes. Blew out a lot of carbon dust, but all appears excellent. No evidence of overheating anywhere or sticking brushes in springs and guides. Put it back on, no change. I am reading 100% throttle from ITS to controller. The only fault code I am getting is LOW BATTERY VOLTAGE and after clearing, it re-appears after every test ride. Have changed and replaced with new solenoid switch, no help. Have checked all connections and cables. Pulling my hair out ! WHAT AM I OVERLOOKING ?

BGW

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

scottyb

A voltage sag under load?

sthreatt

Yes, I am assuming that is what the Curtis handheld is telling me, but I have monitored voltage under road driving and it shows a battery voltage drop from 51 to 41 volts at full throttle road speed. I did the same on a 2016 RXV and it also showed the same drop at full throttle on the road, but with the RXV we were actually moving about 26 MPH, so I assumed the voltage reduction was normal.

sthreatt

Also for got to mention. I have pulled the batteries and replaced with a new set. Same situation. No change. I have worked on many carts of many descriptions but this is the first one that has whipped me well in a fair fight and left me laying in the dust.

cgtech

41v at max speed, full throttle is absolutely horrible. You have a bad cable, or a bad solenoid, dropping a ton of voltage.

BobBoyce

The loaded battery voltage is directly proportional to the load placed upon the motor, the high current cables guage, and the condition (health) of the batteries. A number of factors determine motor loading. Tire size, tire pressure, cart weight/load, surface and grade of where you are operating it, ect. I am very familiar with the 1206HB-5201 controller. I reprogram them to deliver more power to the motor, which equates to more torque. At 41 volts, your controller is starving for energy. The most common issue is oversized and/or underinflated tires causing increased rolling resistance that the controllers maximum current cannot overcome. Therefore the controller cuts back in order to survive.

Bob

sthreatt

I did consider rolling resistance. Checked tight brakes, none, bad front bearings, none, cart has a 6 inch lift and 23 inch tires, brand new and properly inflated. No resistance issues to be seen. Operating on level paved road.

sthreatt

When I say that I am monitoring battery voltage during a test ride, what I am looking at is the handheld diagnostics monitoring battery. I am not actually looking at a VOM connected to pack voltage at + and - . Maybe I need to do that and see if it's actually corresponding with what the controller is telling the handheld. Just assumed it would be.

JohnnieB

What is the maximum inflation pressure stamped on the tire's sidewalls?

If they are the low pressure type (<10PSI Max), they take more torque to turn than higher pressure type 23" tall tires, and even the high pressure type 23" tall tires require 22% more torque the stock (18") height tires.

scottyb

Just reviewed a monitor file for a similar cart using the Alltrax toolkit. The file showed where the throttle went to 100% the the motor pulled 400 amps drawing the voltage very low. Something similar could be happening here, a good pack should not drop more than a few volts at full throttle unless you are in a very steep climb.