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Free spinning a motor (a lot) without cooling

Posted: Thu Nov 13, 2025 10:56 am
by Scrappyjoe
Hello,

I'm midway through a hybrid camper conversion project, and one diff has an outlander rear motor on it, and the other has the original petrol engine. The outlander rear motor turns when the wheels turn, but it is not hooked up to an inverter or cooling lines.

December is coming, and we are planning a long (200km+) camping trip. Is it safe to just plug the coolant holes and drive for such a long time, or do I need to implement cooling (pipes + radiator + water pump) before we go? There will be no load to speak of on the electric motor, but the diff and motor will be spinning at highway speeds for several hours at a time.

Re: Free spinning a motor (a lot) without cooling

Posted: Thu Nov 13, 2025 5:34 pm
by tom91
This is fine. Motor can freewheel.

Just do not join any of the phase leads.

Make sure to plug all holes not to get an debris or moisture in there.

Re: Free spinning a motor (a lot) without cooling

Posted: Thu Nov 13, 2025 7:59 pm
by Scrappyjoe
Thanks Tom. Yes, that’s the plan - seal all holes well and isolate the phase wires with multiple layers of insulation and then wrap it all in thick plastic and cable tie to the underbody. It’s a high vehicle so it should be fine.