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I'm trying to build a robot that will use two motors at 24V. Yet to measure how many amps they will consume. My motors controllers can only do 23A. Planning on accelerating slowly with the hope that I never exceed 23A on each controller. I will also be running a wireless router (12V 2A rated), small computer (12V 3A max), arduino, couple of logitech cameras off a USB Hub (hub is rated at 12V/5A).

I'm considering using standard SLA batteries.

What is the best way to protect from shorts, accidental current overdraw, and reverse connections? I have seen some automotive circuit breakers rated at 50A. Is there a single solution that addresses all of these or will I have to have separate solutions to address each (shorts, over current draw, and reverse conditions)?

I see that this topic addresses similar question, but is targeted for low amps. I need something that can handle 60-80A.

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Bot Builder
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  • I think you have failed to grasp that showing no research into possible solutions does not bode well for getting reasonable answers and avoid closures - in this particular case I suspect that it might be on soliciting opinion - opinions may be right today but next week they'll be out of date and the chosen answer for today will be wrong. Try and find one that folk can comment on. – Andy aka Nov 13 '15 at 15:00

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The best way to handle a short, is a fuse. It is a device that is guaranteed to clear (open) on a fault, they can be purchased to be anywhere from extremely fast blowing to time delayed, and still today, ultra fast acting fuses are the method of choice to protect power components in motor drive controllers.

A sufficiently large diode will protect downstream components from hooking up the battery wrong.

What do you mean by "Accidental Current Overdraw"? For a medium duration, moderate overload condition, a thermal trip breaker or even a motor starter protector might work, but I'd put such a protective device on each power drawing component (or subassembly), and not just one on the source (Battery).

R Drast
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  • I could have phrased "accidental current overdraw" better. I meant when the motor is stalled, it will likely pull many more amps than normal operation. Wanted to prevent the motor from going crazy and killing the controller somehow. – Bot Builder Nov 13 '15 at 14:34
  • Any recommendations on a large diode? Or types of diode for applications like this? – Bot Builder Nov 13 '15 at 14:34
  • For the motor stall condition: Ideally, your motor controller will have an internal current limiter. The typical motor drive control has an outer speed regulator loop driving an inner current loop. There are almost always adjustable limits on that. For the diode, any old diode rated for your maximum current should work. Look for one that mounts easily for you. – R Drast Nov 13 '15 at 15:50