The obvious answer is that the cold temperatures mean the chemical reaction in the battery is slower.
But, can anyone with a better understanding of motor controllers than me explain how this is different from the battery only being, say, 30% charged?
At first I thought it was because in the cold this is all the power the battery could push through the motor’s coils, but (a) I’m sure if you stuck a spanner across that cold battery it would still push an insane number of amps before it exploded and (b) the “powerbox” would do absolutely nothing in cold weather… which I’m sure isn’t the case.
Then I thought maybe it was a simple mark-space/PWM modulation scheme in the controller (like a domestic light dimmer *edit - not an exact analogy, plus the battery is DC…) which didn’t compensate for the reduced input voltage… but then the Twizy would get slower and slower as you drove, through the normal discharging of the battery.
Presumably then, the motor controller modulates power (not just voltage OR current) in a more sofisticated way. So back to my question which is just, how is cold weather different from partial state of charge? Can anyone enlighten me, just because I’m interested! Thanks!!