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Cooling strategies

Hello, I have three OpenEVSE units in two locations. One unit is set to 16 amps max due to the circuit. The other two are connected to 14-50 outlets and set to 40 amps, and these both experience overheating cutbacks in hot weather. Today is in the mid-to-upper 80's, and the past two weeks were in the 90's (F). Charging my car, max load around 29 amps, these two units will cut back at 65°C. Attached file is a screenshot of the current charging session. The blue line is approaching 7kW, and the red line is just touching 65°C before the cutbacks. I've read the various other threads on ventilation, I'm running the latest firmware on all units. I even added a 1" 12v fan to one unit to stir the air, which helps. But I'd like to reduce the heat buildup itself. Are there mounting options that would help? Spacers for an air gap behind the unit instead of mounting directly to drywall or plywood? A metal backing plate? Should I add solder to the crimp connections to reduce resistance? I've also noticed that the contactor has little sharp turned up corners where the ring terminals meet. These make it hard to get the ring terminals to seat flush. Are there any strategies that help with that? Just looking for some ideas.
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3 CommentsSorted by Oldest First

The temperature monitoring and throttling feature is very conservative. If you can afford a few extra minutes of charge-time then let the throttling happen as designed otherwise use the menu or WiFi to disable the feature.


The idle temperature will be about 2 - 5C over ambient, there is very little that can be done here as a station is only using about 1.5w with WiFi running.


During a charge session temperature rise is dependent on current. Reducing resistance will reduce heat, the largest factor is the wiring gauge. Thicker wires will reduce resistance/heat. Improving the connections to the relay may help but should not be a factor unless the connection is loose.

I added a 1" 12v fan internally to the unit, it seems to help a bit. I checked the connections, everything is tight. I also added some stick-on heat sinks to the sides of the unit, it's questionable if they have any affect.  At 65C / 149F the button is hot to the touch, I'd hesitate to remove the temp threshold as I'd worry that my daughter would burn a finger if it got much hotter.


Idle temperatures aren't a problem, as you said they end up a bit over ambient.  I'm still getting occasional overheating when charging, and my car only pulls 28 amps (on the 40 amp unit).  If I upgrade to a higher power EV I would like to be able to feed it full power.


Even with the recent modifications, I had another temperature event this September evening (it was a warm day).  I'll keep playing with it to see what I can do.  I was just looking for some guidance to see if you had luck with other types of mods.

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How about longer mounting screws and 1" spacers on the back? This would allow cooling and airflow on the backside as well and keep heat from the structure from soaking into the enclosure.



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