Possible overheat

I was using the range extender the other day there to burn off some of the old fuel that had been sitting for about 5 months. I was doing 70mph constantly along a dual carriageway. The engine wasn't quite able to keep up as the battery charge was still going down slightly. The coolant temperature went to 98 celsius and when I got home there was a slight burning smell and the fans were on in the back.

Sounds totally normal to me......

If you are using Rex, especially at full power, the fan will stay on when you stop, just as in an ICE car. I usually try to turn Rex off a few miles before stopping to avoid this. It is rather noisy and smells hot.

Think of it this way...at 70mph and you noticing that the battery level was still slowly dropping, that means that the Rex was running flat out. How often do you run a motor flat out? Now, it is rev limited, but still, things are going to get hot. FWIW, on an ICE under a heavy load, it is not at all uncommon for the coolant to get above the boiling point which is why it is under pressure so that it doesn't boil at the 'normal' 100C.

I repeated the test again today and noticed that the temperature reading increased from 86 celsius to about 95 after the engine was switched off. Strange.

sdobbie said:

I repeated the test again today and noticed that the temperature reading increased from 86 celsius to about 95 after the engine was switched off. Strange.

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Not really strange. The combustion chamber is MUCH hotter than the coolant, and when things shut off, that heat migrates. An ICE functions in the same manner. During operation, oil also acts like a major component of heat exchange, and with the motor stopped, that stops as well, and it's temperature goes up, too. Original turbo chargers used only oil for coolant, and if you didn't let them cool down after a hard run before shutting the vehicle off, long before synthetic oil became more common and they changed the turbo cooling to antifreeze, that could cook the oil, causing premature failure.

What you're seeing is normal after a hard run. That engine produces more power and can run faster when used on a scooter. IOW, it can handle it.

sdobbie said:

I repeated the test again today and noticed that the temperature reading increased from 86 celsius to about 95 after the engine was switched off. Strange.

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aka heat soak

...just addin': also the coolant stops circulating through the radiator when an engine is switched off, so the remaining heat cannot do anything else than warm up the lump of ICE iron. Every car does it.

Regards, Steven

And that rising heat warms the cargo area floor as well as the rear seat cushion! Will be perfect in the winter

rear heated seats :lol:

For men in the backseat it's known as..."Glow-ball warming"! ouch