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48v or 24v motors for an electric cart

I am building an electric cart with two drive wheels and two front steering wheels. I have two 24V, 650W motors. I am wondering if I should buy a 48V controller and run the motors in series or buy two 24V controllers and run each motor off its own controller. It would be cheaper to go 48V. I have a good selection of batteries to choose from to keep the weight reasonable. I can do 2 big batteries for 24V or 4 smaller batteries for 48V. Also, I will be using the cart in the woods where I have a 48v solar system, so charging a 48v system will be easier. What are the issues I need to consider? I have hooked up the motors in series and touch the leads to the 48v battery and the wire draws many amps and somewhat melts the battery post. I'm hoping this won't be the case when I use a speed controller.
I have not tried wiring two motors together in series before on an electric cart, so I do not have any experiences with that type of wiring arrangement. It sounds great in theory though and I imagine that when one motor is loaded more than the other when the vehicle is making a turn more power would be supplied to the motor on the outside of the turn which would be optimal. I have not done this before though so I am not sure exactly how it would work out on a real build. My feeling is that it would work great though.

However running each motor from a separate 24 Volt controller would be the safer thing to do since that is a tried and true method.

Regarding the battery posts melting when the motor leads are touched to them that is caused by the massive amount of power required to bring the motors from a standstill to running speed. A controller will eliminate this problem by ramping the power that the motors receive at startup.

Please let me know if you have any further questions.
thanks for the reply. i have received the 48v controler SPD481500 and Throttle THR-115. I hooked everything up but have a question. The speed of the motors seems to be the same regardless if the throttle is connected or not. Once i make the battery connection, the motors turn on at what seems to be full speed. i eventually disconnected the throttle completely and again, once i hook up the battery, the motors jerk on, at full speed. any ideas?
That type of problem is usually caused by a wiring misinterpretation. Would it be possible for you to attach a photo of the wiring so I could have a look at it?

thanks.  I could not get a good picture, but here is how I wired the system.

The THR-115 instructions say the BLACK wire is GROUND but there is no BLACK wire on the unit.  I assume the
BLUE wire is the GROUND.  I left the YELLOW unconnected.


The throttle is wired correctly in your drawing. The blue wire is ground. I corrected the THR-115 wiring instructions on the website to show blue as the ground wire.

If the motors run at full speed with the throttle unplugged from the controller then the throttle could not be causing the problem.

The wiring in the drawing is correct. The motor running at full speed could be caused by incorrect polarity. Do you have a multimeter that can be used to test the Voltage and polarity at the motor disconnect with the motors disconnected?
Thanks for the assistance. I am an experienced electromechanical tinkerer. I have checked the wiring before connecting the power. I just now re-checked the polarity. At the motor disconnect, I have the proper polarity and 50.4v. I am thinking the controller is defective. What do you think? Thanks again.

It is starting to sound like a faulty controller. Before we narrow it down to the controller though could you please check and verify that the cart's frame is not grounded to the battery pack?


Grounded frames are known to cause problems like this. The frame should not be connected to the ground or positive leads of the battery pack.

I have confirmed that the battery, controller and frame are not grounded. Thanks.

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