After the charger failure, I'm keeping a closer eye on the new one and have been reminded that after several hours of charging, the top cover is extremely hot to the touch (actual temperatures coming soon), much warmer than the outbound coolant line. My pump is running and there is vigorous circulation, but of course, that heat exchanger is in the bottom of the box where it can't do the most good. Since the little filter box on top of the charger is in firm contact with the sound insulation on the underside of the motor room hatch, it has little chance to cool off.
For how much heat we're dealing with, at 96% assumed charger efficiency, 4% of 3300W= 132W or 640 Watt-hours per full recharge.
Throw in the DC-DC operation and I'd bet we're dealing with as much as 1 kWh of waste heat. To remove just 0.5 kWh of heat we'd need to soak up 1706 Btu.
SO, I'm considering the following unprioritized list of options.
#1- Remove some insulation to create an air gap above the charger. (and then likely add Dynamat to offset any increased noise)
#2- Add a ducted fan fed by the charger AC input to blow cool air across the top of the charger or pull hot air away.
#3- Add a liquid-cooled cold plate atop the charger and plumb it into the coolant loop.
(here's a candidate https://www.shopaavid.com/Product/416401U00000G
Once could alternatively make a copper coil or use a tiny radiator designed for computer overclocking. I also a tiny heater core that serves to preheat winter combustion air in a Honda Odyssey.
#4- Add a bladder full of phase-change wax to serve as a heat sink atop the charger. Paraffin with a phase change at 84 degrees F will absorb 87 Btu/lb in the melting process. So, a whopping 20lbs of wax would be needed to reduce the heat by half, and not help at all on a warm summer day... wow. no go there
#5- Cut a hole in the motor room hatch and put a butterfly vent in so that the hot air rises into the cabin. Free heat in winter, but less effective in summer when needed most. https://www.etrailer.com/Enclosed-Trailer-Parts/Redline/371800.html?feed=npn&gclid=EAIaIQobChMItfjtpeqX3AIVGMRkCh3JYQoxEAQYASABEgLEK_D_BwE
#6- prop open the motor room hatch during recharging and open the windows a crack...
Comments please. Is any of this worthwhile, or is a charger replacement every 50-90k just to be expected?