Pulling max amps (2x30A) for more than 30s (AX1500)

9 years 11 months ago #29526702 by Anonymous
We are designing a an autonomous robot for a competition and I am using the AX1500 to control the motors. We did a calculation and need to pull 30 amps from two motors for a few minutes. I see in the manual that it is not recommended to pull 30 amps for more than 30 seconds. It says if we manually cool, we can pull 20 amps for an extended period of time. What we are looking to find out is this: Can be pull 30 amps from each motor for an extended amount of time (about 6-7 minutes) if we force cool it well. We just want to know the limitations of the controller. We understand that it is a temperature sensor that controls the current limitation, so if we cool it rapidly, can we pull 30 amps from each motor for 6-7 minutes? We are just trying to find out the current limitations without breaking it. Is this possible? We can use a heat sink and or force cool with fans, but we figured we would write before we tried it so that we did not blow the controller.

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9 years 11 months ago #29526703 by Roboteq
It should work. You may want to put a fan.
FYI, at 2 x 20A, the controller will generate around 2 x 20A * 20A * 0.12 ohm = 96W. That is quite a bit of heat energy you will need to remove.
The controller will start cutting max power when reaching 70o C.

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9 years 11 months ago #29526704 by Anonymous
I just want to clarify some things:
1. We were looking for the total resistance, I am guessing it is 0.12 Ohm.
2. We were going to try to pull 30 amps from each motor (60 amps total) from the battery through the controller to the motor for about 6-7 minutes at a time. As long as we keep the temperature below 70 degrees C, we will be okay? Do we need to wait any amount of time in between the 6 minute cycles of 60 amps?
We are probably going to use a combination of heat sinks and fans, so I think we should be safe.

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9 years 11 months ago #29526705 by Roboteq
The key thing is to stay below 70o. If you can cool it enough that it remains below 70o, you could run forever. If it overheats you will need to wait for it to cool down. It is not really possible to predict how long this could take until you run tests.

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