Amp pull “at rest” for Curtis Controller

OnI have an electrical go kart using a 48 V AC-9 motor and a Curtis 1236 SE controller. The controller software menu (under controller current and controller temperature), shows that the current (amp) range is between 2.0 and 4.2 Amps with no throttle action at all and the Controller temperature seems to be rising very slowly. Keep in mind this is with no throttle. Does that sound right? Why would there be between 2A and 4 A of current when there is no throttle action? Thanks for any suggestions. Gary

garolittle said:

OnI have an electrical go kart using a 48 V AC-9 motor and a Curtis 1236 SE controller. The controller software menu (under controller current and controller temperature), shows that the current (amp) range is between 2.0 and 4.2 Amps with no throttle action at all and the Controller temperature seems to be rising very slowly. Keep in mind this is with no throttle. Does that sound right? Why would there be between 2A and 4 A of current when there is no throttle action? Thanks for any suggestions. Gary

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Hi Gary,

If the controller is on and enabled (signal to forward or reverse command input), then it is supplying magnetizing current to the motor in anticipation of soon getting a torque command. This shortens the response time. It is often called no load current. It is 3 phase AC. But mostly reactive so a low real power and low DC from the battery.

Also the controller outputs the coil power for the contactor(s) and sensors. This comes from the battery.

Are you seeing DC or AC as controller current? I'd expect AC to be higher. Also check to see you are getting zero throttle command. A few percent could draw some power yet be too low to move the vehicle.

Regards,

major

major said:

Are you seeing DC or AC as controller current? I'd expect AC to be higher. Also check to see you are getting zero throttle command. A few percent could draw some power yet be too low to move the vehicle.

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major .... Thanks. This is great information. I will double check but I am nearly certain that there is zero throttle power unless I’m pressing the pedal. In the meantime I have an embarrassing question ..... It is an AC controller so why would there be DC current? Basically the controller acts as an inverter (among other things) so I would think that no DC power “comes out” of the controller. Forgive me if this is a simplistic overstatement. I do not have an electrical engineering background so I have to state things in plain language. Thanks again for your great information. I really do appreciate it. Gary.

No worry. DC refers to battery current. Been a while since I used the Curtis AC drive and I don't recall if they monitor and display DC or not. That's why I asked.

Edit. BTW. The controller does output some DC, like 15, 12, & 5V for throttle pot, communication, and sensors. And also a selectable DC voltage to drive contactor coils.

Ahhhh. Understand. You are correct. There are 5V and 12 V DC outputs. I know this because I’m about to install a charger for my iPhone. I can also monitor the DC voltage from these outputs as well. Let me run some checks tonight and I will let you know what I find out. In the meantime thank you very much for your reply. I really appreciate it. :thumb:

major said:

No worry. DC refers to battery current. Been a while since I used the Curtis AC drive and I don't recall if they monitor and display DC or not. That's why I asked.

Edit. BTW. The controller does output some DC, like 15, 12, & 5V for throttle pot, communication, and sensors. And also a selectable DC voltage to drive contactor coils.

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OK. So I was wrong (which is great because it means I just learned something). The throttle voltage is present “at rest”. As you can see from the first photo the throttle is pulling about .26 V at rest. Also I can see the amps pulled by the controller at rest (see second photo below) but I cannot determine if that is DC or AC power. Thanks again for all your help. Any other suggestions would be great.

Current (RMS) would be AC.

RMS = Root Mean Squared

major said:

Current (RMS) would be AC.

RMS = Root Mean Squared

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Thanks major. Hope all is well.