I just finished building a home made "mini" golf cart. I am having issues with the motor stalling though.
1000W - 48V Brushless Motor with gear reduction 1:5
1000W 48V rated controller
Full load current :28A / No load current: 5A
Rated Torque : 3.4 N.m
Rated RPM: 2850rpm motor / 570rpm shaft after gear reduction
Motor Sprocket: 20 T
Axle Sprocket: 41T
4x 12V 8Ah with 6-AWG Wires
~350lb Golf Cart + ~180lb Driver
Initially the motor came with a 14T sprocket, and I had 13" Tires installed. The golf cart was accelerating well but I had a max speed of 9mph. The top speed I am looking to achieve is about 13mph so i decided to change the motor sprocket to 20T and install bigger tires. That is when the issues began.
The golf cart stalls when I press the pedal throttle. It tries to start moving but it seems that the controller cuts off power to the motor. It feels like a lot of torque and instantly stalls. I have to let the pedal go and try again. Sometimes, if I press the pedal very slowly, it starts moving, yet it keeps stalling, thus never reaches max speed.
Surprisingly, I have no issues with reverse on flat ground, but sometimes the motor stalls when I try to go reverse over a driveway "curb" or in the grass.
It also feels like it generates a lot of torque once I initially press the pedal, (both forward and reverse), meaning no smooth acceleration at low rpm.
I understand that by changing the sprocket ratio to gain speed, I also loose torque, yet the motor seems to initially "kick" strong for a second, just before it stalls. Also it is good to mention that the motor does NOT get hot at all !!
I checked the batteries individually under load as well as a pack and they seem OK. They are 8Ah batteries, but once I get the golf cart fine tuned I will purchase good 35Ah batteries.
Now, below are my thoughts in regards to the cause of the issue and I will appreciate any support/suggestions based on your knowledge and experience.
A. The pedal might be defective (Chinese unbranded pedal)
B. The Controller is damaged
C. The sprocket ratio is way off the maximum capabilities of the motor
Possible Solutions that I am thinking:
A. Go back to 14T motor sprocket (or maybe try 16T), sacrificing max speed but gaining torque
B. Replace the pedal and/or controller (costly solution without solid confirmation that will resolve the issue)
C. Replace the motor and controller to 48V or 60V but 2000W. (costly and yet still unknown if the problem is the existing controller failing)
D. Over volt my existing 48V/1000W motor to 60V. (chance to burn the motor and also I will need to purchase a new controller since my existing controller is rated 48V 1000W). BUT I will appreciate your thoughts on this topic since I haven't over volt a motor yet.
I will appreciate any support/suggestions based on your knowledge and experience, in order to resolve this issue.