Sealed cooling
-
tinkeringtechie
- Posts: 9
- Joined: Wed Jul 12, 2017 9:53 am
Sealed cooling
My project has relatively low power requirements: 24VDC with ~1A per channel on the 2x15A roboclaw. Originally I thought I could get away with just putting it inside a sealed enclosure, but on hotter days the controller has been getting scary hot (90C). Unfortunately my project is in a very dusty and even occasionally damp environment, so open ventilation isn't an option. Any ideas for ways to cool it that are "outdoor friendly". Ideally I was thinking of a heatpipe solution that could get the heatsink out of the enclosure while keeping the electronics safe inside. I haven't been able to find one that would fit the roboclaw though.
-
Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: Sealed cooling
What is the temperature in the enclosure without actually running the motors(eg the controllers on but just sitting there doing nothing? Whats the ambient temp outside the enclosure? Is it in direct sunlight?
90C is WAY too hot for 2x 1A motors so something else is definitely going on. Under normal conditions you shouldnt see any significant heat increase above ambient(a couple degrees C but you'd get that just sitting idle as well) in the 15a from 1A current loads(its basically nothing). Im assuming you are measuring the temp by reading the Roboclaw values?
I also assume you are reading the current from the Roboclaw? If you are measuring it from the battery manually then the current could be alot higher at the motors(where it counts) so you hsould be reading current from the Roboclaw directly.
Note fully sealed plastic enclosures are not going to work in general. Most plastics thermal conductivity is horrible so you could be basically boiling the controller slowly(eg the heat has no were to go so even a little heat is builting up. You need a metal or at least partially metal enclosure so the heat can get out since you cant have any air flow. Mount the roboclaw so its plastic base is touching the metal(its thermal conductivity sucks but its better than nothing).
You should also check the board temp when running the system without being in the enclosure(or at least open to air) to see what the temp differences are.
90C is WAY too hot for 2x 1A motors so something else is definitely going on. Under normal conditions you shouldnt see any significant heat increase above ambient(a couple degrees C but you'd get that just sitting idle as well) in the 15a from 1A current loads(its basically nothing). Im assuming you are measuring the temp by reading the Roboclaw values?
I also assume you are reading the current from the Roboclaw? If you are measuring it from the battery manually then the current could be alot higher at the motors(where it counts) so you hsould be reading current from the Roboclaw directly.
Note fully sealed plastic enclosures are not going to work in general. Most plastics thermal conductivity is horrible so you could be basically boiling the controller slowly(eg the heat has no were to go so even a little heat is builting up. You need a metal or at least partially metal enclosure so the heat can get out since you cant have any air flow. Mount the roboclaw so its plastic base is touching the metal(its thermal conductivity sucks but its better than nothing).
You should also check the board temp when running the system without being in the enclosure(or at least open to air) to see what the temp differences are.
-
tinkeringtechie
- Posts: 9
- Joined: Wed Jul 12, 2017 9:53 am
Re: Sealed cooling
It's in a black plastic enclosure that it also shares with a Solo. So basically the worst of all characteristics. Sounds like I need to hunt for an aluminum enclosure and see how that goes. Bolting the solo to a metal enclosure should take care of that one, and the 2x15 should benefit as well. Thanks for the ideas.
-
Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: Sealed cooling
Yes. The solos are specifically designed to be mounted directly to metal. Conduction through he plastic bottom on the 2x15 isn't great(its designed to cool primarily from the heatsink) but the current is so low it shouldn't heat up very much. The critical thing is the ambient and if its in direct sunlight. Enclosures in direct sun get extremely hot.
-
Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: Sealed cooling
Do you mean you cut a whole in the NEMA case or the MCP case?
With thermal paste less is more. You want to use just enough to fill the small irregulatiries so there are no air gaps. If you have a large gap that needs to be filled you want to use a thermal gap filler instead. They have a much higher conductivity than most pastes and are designed to conform to irregular shapes.
With thermal paste less is more. You want to use just enough to fill the small irregulatiries so there are no air gaps. If you have a large gap that needs to be filled you want to use a thermal gap filler instead. They have a much higher conductivity than most pastes and are designed to conform to irregular shapes.