David asked: “How much has heat management been an issue for others?”
In my case, I have an ETEK motor and ALLTRAX controller both mounted inside my outboard motor cowling. This could be a recipe for heat-induced disaster had it not been for some attempt to keep this all cool. And while my controller is mounted vertically to a heat sink that itself has a muffin fan blowing on it, and while the motor has an aluminum shroud that connects its own 7” muffin fan to pull air thru the motor to cool it, all this wouldn’t be enough without providing some means to get the heat out of the cowling itself. The air inside would gradually just get warmer and warmer---add to this the graphite dust from the motor brushes and it wouldn’t be pretty. Fortunately, even with the muffin fan above the motor and aluminum shroud, there’s still about 1” above the fan and the cowling itself has a vent at the rear. Solution: Build an air plenum or “false top” inside the upper part of the cowling which accepts the motor fan’s exhaust air--- cool outside air is pulled up thru the motor, out the fan on top, then up into this new upper chamber of the cowling, then vented out the top. While this works fine all the way up to the 6HP that can be dished out, ideally it could use even more forced air to run a little bit cooler. At 10% heat loss, 4.5kw (6HP), there’s 450watts of heat that the motor is trying to shed at full power---that needs to be taken seriously.
-Myles
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