Slow 2002 Club Car DS

[olmsrbl]

I was gifted a 2002 Club Car DS 48v. So we could ride our special needs child around in neighborhood. I bought new batteries because the batteries in it would not charge. I changed all battery cables during all of this. The cart goes forward and backwards. It is very slow going up hills and real fast on flat surfaces. I jacked the rear-end up and had my wife press the gas pedal so I could read the voltage to motor. It has 46v going to the motor. So is it the motor or something else? I have tried to find videos and such with no luck. Any help is appreciated because my son lights up when he just sits on the cart, so I can just imagine what is going to happen when it moves. Lol Thanks everyone.