I am close to finishing a project which will control some garden lighting. An LED strip and LED deck uplights.
The 24v and 12v drivers are IP67 rated so that's cool, but I need something to house the Wemos and the MOSFETs. I can buy IP67 cases from Ebay no probs, but I am concerned about heat build up, as IP67 rated is going to be practically air tight.
Am I better keeping that stuff inside, running power to the drivers and then run a signal loom from the WEMOS outside to the lights? Or should I look to modify a waterproof box with some cooling in someway?
You can do the thermal calculations if you like. I would suggest you pick MOSFETs with a low RDSon, they will cost a little more but run a lot cooler. Be sure when you drive them they are fully saturated and nothing greater than 50 Ohms to the gate with the pull down resistors on the arduino pin not the gate. The gates are capacitive and PWM without proper drive will cause them to get very hot. You can always get a small fan and place it in the case, that will help distribute the heat to all sides of the case. Since I do not know the size of the case, the loads, the material the case is made out of I can only take a guess but it is probably close.
Yes heat build up is a problem with airtight boxes especially plastic ones.
You could use a metal die cast box for better thermal conduction, or you could bolt a heat sink on both the inside or outside of the box.
If doing this use plenty of bolts because they are the only thing conducting the heat from the inside to the outside. Don’t use stainless steel as they have a poor thermal conductivity, I would have thought brass would be the best material.
Ah yes, didn't think about a metal box. The MOSFETs are in TO 220 package. Could potentially attach directly to the case to disapate the heat directly.
Only concern with the metal box is blocking the WiFi signal.
Thinking keeping the controller inside and running a multi core wire to carry the light channel signals and bring a common ground back might be the best way.
I would use a plastic box then. Although any opening in a metal box is not going to have much effect on a Wi-Fi signal, much less than many people think.
You could cut a hole in the metal box and fit an acrylic patch over it. Have nuts and bolts holding it on and use bathroom sealer to make it water tight.
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