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Originally Posted by e*clipse
I wonder what would happen with the cooling fluid, seals and all that stuff when it gets to -40C ? I've heard they just run the trucks 24/7 when things get that cold up north.
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Diesels, I'm told, sometimes have trouble starting even when they have had engine block heaters used. I have heard stories from truckers that they leave their diesel rigs running all winter, but that is further north.
50/50 glycol/water mix is good to -50F. Thankfully I have not seen that mixture start to gel. Gasoline DOES start to freeze up around -40F and our winter gas has an antifreeze additive included.
On my gas vehicles, I normally plug in the engine block heater, at work and at home, plus a small interior warmer on a timer - about 4 hours before I go to work and 4 hours before I leave. They vinyl seats are much uncomfortable when they are frozen. If your battery is a couple of years old, a trickle charger on the battery when parked helps as well.
My 92 mazda MX6 has CV boots that do NOT like that cold weather (early Japanese design). If I run it at -40F the life of the boots is measured in weeks, not years. Al of the rest of it - seals, gaskets, etc - appear to have paid attention to the full operating temperature range
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Another issue - for EV's would be can the batteries handle those extremes? As with many compromises, it really wouldn't pay to match an extreme rating in one critical part if another critical part couldn't handle the same conditions.
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The performance of the batteries is expected to be poor at the extreme temperatures. The energy is not lost, but the batteries need to heat up in order to have the chemical reaction release it's stored energy.
I have some ideas on battery box insulation, a battery warming system that I can plug in and circulate warm glycol around the battery box, etc. Of course, I have to get the MX6 finished (to a point) and on the road .. then when it's running I can experiment with that sort of stuff. I have it from EVTV that charging lithium cells below 32F does permanent damage, so unless I get some sort of warming going on, it will be a 3 season car.
The controller could very well be in the engine compartment or near the motor. No warming available until the electric motor needs cooling. The current sensor is one of those things that needs to work, within temperature spec, to make the controller function properly, right? It's not optional, like the LCD. If the accuracy drops to 5% instead of 1% - no big deal. If it stops working at all, or is damaged ... well, that's another story!
I do not mean to make a big deal of this. This is one design decision in a long list of design decisions. If the design decision is to have -10C as the lower limit, it's simply a limitation that must be listed. Anyone that has to deal with lower temperatures will need to deal with the limitation somehow or spec a part with a wider temperature range.