This is a new one to me in four years of Tesla ownership. I'm used to the projected range numbers on the battery from my TeslaMate data tracker getting lower in winter as the battery is less efficient and spends more time heating the battery, but yesterday I saw something very odd. Took it to a supercharger to do a full battery charge and balance the cells. From the time the charge indicator indicated it was at 100% until it actually stopped charging was 40 minutes (when it hit 100% it was at 8KW of charging and slowly dropped over the 40 minutes). I've seen that behavior before. What I had not seen before is that on the trip meter, the battery level indicated 100% for almost 18 miles after I left the supercharger (see picture below). Then when it did start to drop, it stayed at 100% until the battery was at about 97% according the graph scale...and then it jumped to 99% (see second picture below). About 10 miles later the percentage readout matched the scale.
My first thought was that the computer was recalculating what "100%" is and it would normalize out, raise the projected range data, but it did neither. In four years of ownership, I've never seen it sit at 100% (or any other percentage for that matter) for such an extended period. Note this was all highway driving at around 65mph so I have a good feel for how the battery line drops at those speeds. The behavior was almost like an ICE car that has been topped off such that there is fuel in the fill pipe leading to the tank and the tank float stays at "full" for a while until that fuel all gets used up. Obviously there is no equivalent of storing excess energy in a BEV, but I am at a loss to explain this behavior. My guess is that the BMS calibration is off.
So my questions for the wise experts on this group: Have any of you seen this behavior before? Is it normal or a sign of a BMS issue? Is there a way to correct/recalibrate it? I'm looking at taking my car in for the four year service next month (yes I have the prepaid service plan and am debating whether to cancel it and get the refund or force the service center to do everything that is on the plan contract...year four is quite extensive). If I need to get the service center to do something regarding this potential BMS issue, that would be the time to do it so would appreciate thoughts/feedback/suggestions.
My first thought was that the computer was recalculating what "100%" is and it would normalize out, raise the projected range data, but it did neither. In four years of ownership, I've never seen it sit at 100% (or any other percentage for that matter) for such an extended period. Note this was all highway driving at around 65mph so I have a good feel for how the battery line drops at those speeds. The behavior was almost like an ICE car that has been topped off such that there is fuel in the fill pipe leading to the tank and the tank float stays at "full" for a while until that fuel all gets used up. Obviously there is no equivalent of storing excess energy in a BEV, but I am at a loss to explain this behavior. My guess is that the BMS calibration is off.
So my questions for the wise experts on this group: Have any of you seen this behavior before? Is it normal or a sign of a BMS issue? Is there a way to correct/recalibrate it? I'm looking at taking my car in for the four year service next month (yes I have the prepaid service plan and am debating whether to cancel it and get the refund or force the service center to do everything that is on the plan contract...year four is quite extensive). If I need to get the service center to do something regarding this potential BMS issue, that would be the time to do it so would appreciate thoughts/feedback/suggestions.