So stopped at my usual Petro Can. to charge. In the past it charged at about 44watts or whatever. The temp out at those times was about 6*c Today at 0*c it would only charge at 25Watts It was like the charger Had been tapered down . Saying that was it the charger or my Kona. I even changed chargers . Both did the same ..
If you used the same charger you always use, it could be several reasons. The charge speed depends on: - state of charge of your car/battery - temperature of the battery So it's hard to say why exactly you experienced a slower charge rate. But it's likely one of those.
Until the battery warms up, the car slows down the DC charge rate to protect the battery. I thought you Canadians had the battery heater on your cars though. Have you turned on winter mode? How long did you leave it plugged in, and did it speed up after charging for 10 minutes or so? Also, out of curiosity, how long had you been driving before charging? The only time I've had to DCFC below freezing, it was in the middle of a long drive, and we had nice fast charging rates at -3C. I figured it was because the highway driving had kept the battery warm.
So the car was warmed up in winter mode. after 10 KMS I charged for 1 hour and it never sped up at all. temp 0*c it did puzzle me. I also changed charger as stated... next week i will see how it goes. This charger has been down twice since it got up and running..
My guess would be that 10 km isn't a long enough drive to get the battery warmed up. I've planned my trips to charge later in the trip, so that I've done at least an hour of driving before DCFC. It would be interesting to hear from someone with the monitoring app how the battery temp changes during a highway drive on a cold day without a battery warmer.
I have good luck rapid charging after driving an hour or two. But I have no battery warmer, so that's the only way I can get it warmed up to get a decent charge rate. At home I have a L2 charger. No issues there.
I think I had read somewhere else, possibly even on this forum regarding winter mode and charging that the car has a threshold of 78 degrees F for the battery before it will allow full speed charging. So if your battery was near ambient temperature of -6 C from cold soaking overnight and you simply pre heated the car for say 10 minutes then drove 10 km, its very unlikely you would have had enough heat in the battery to get anywhere full speed charging. Likely had you have either driven longer, say 50 km or pre heated for over half an hour while pluggedin at home then you might have got the batter up to temp. You have to remember that the battery warmer is only 2 KW so even if it was running the whole time, getting a cold soaked battery at -6 C up to over 20 C isn't going to be a fast endeavour.
Its not too bad last time I was fast charging at -9C the battery warmer increased the battery pack by 15C in about 25 minutes.
