I do not understand why my Clarity is charging at a lower rate (in the cold) sometimes. It starts at about 7kW then drops to 4kW. I have noticed on public charge stations (where it should only take me 1 hour to recharge, it is now taking 1 hour 20 minutes. I originally thought that the battery warmer was running and drawing power - extending the recharge time. Then I looked at my home charger graph (below). Does anyone know what is happening?
Can you provide more information about the plot that you attached? 13.51 kWh is about right for a 'full' charge. Your graph shows an overall time span of ~8 hours. The 1st section looks like approximately 25% of this time (or 2 hours). That is about right for a 'full' charge too. Are you saying you connected to the charger at 9:12 PM, and did nothing else throughout this entire duration (until 5:39 AM), and this pattern just happened entirely on its own? It looks to me like you had a normal full charge cycle that terminated in the evening, and then something else happened in the morning (maybe preconditioning for a while, then the beginning of another charge cycle)? Not enough information to help decipher...
This is very interesting. Was your car outside. It might be that it was too cold for the BMS to allow the battery to accept a charge. When it warmed up a little maybe the battery warmer came back on and then finished the charge or replaced the energy it had consumed keeping the battery warm overnight. The temp at the Ottawa airport never got above 16 on the 13th and the temp actually started to rise around 3:00am on Thursday. If your car was always outside and the battery was cold soaked then this behavior would make sense. Sent from my iPhone using Inside EVs
The car is in the driveway outside. What is odd is it starts to charge at “full” power (7kW) then drops. I guess it could be the battery warmer turning on - but you would think that would draw more power - unless the warmer can only draw from the batteries not the 240v line. So maybe the batteries are too cold - but I thought charging the batteries would also warm them up. Also interesting how much power the pre conditioning (cabin heater) draws - and it draws straight from the 240v line. you can also see the battery warmer turn on around 4am and it is drawing from the 240v line.
I’d say it is the BMS at work. Typically a Lithium charging protocol will not allow the batteries to accept a charge if temperatures are below ~25-32F. I guess that would be -2-0C. Temperature sensors immediately began to control the charge. Once the batteries had accepted some charge and warmed up, the charging rate was increased, then tapered down at the end of the charging cycle.
