I did a little more testing recently while I was on a road trip and tried to optimize charge times. I was keeping close track of energy going in and out of the battery on the CAN bus. I noticed when discharging the battery (driving) some of the energy is lost.
Here is an example. The BMS reports I have 40 kWh usable left in the battery. I drive 100 miles and measure the amount of energy I have taken out when I arrive. It shows I have taken out 39 kWh from the battery. Now you would expect there is 1 kWh usable left, right? But in reality, there is 0 left. In other words, aprx 2.5% is lost inside the battery as you discharge it. This isn't surprising at all. A battery has a small internal resistance that causes some losses. 2.5% is actually really good. The efficiency is worse at lower temperatures. The fact that using Range Mode increases battery temperature supports that.
Tesla actually keeps track of this precisely. The BMS measures and keeps track of the entire amount of energy the car has use in it's life. But it keeps track of energy amount charged and discharged separately. This allows one to determine the round trip efficiency of the battery.
What does that mean for range? When the battery is charged fully, the BMS takes the total capacity and divides it by the rated consumption and this gives you the rated range. In normal driving you will have 2.5% losses that occurs over the entire time of the discharge. It means you end up getting 2.5% less range. This definitely confirms the data @supratachophobia has collected.
Here is an example. The BMS reports I have 40 kWh usable left in the battery. I drive 100 miles and measure the amount of energy I have taken out when I arrive. It shows I have taken out 39 kWh from the battery. Now you would expect there is 1 kWh usable left, right? But in reality, there is 0 left. In other words, aprx 2.5% is lost inside the battery as you discharge it. This isn't surprising at all. A battery has a small internal resistance that causes some losses. 2.5% is actually really good. The efficiency is worse at lower temperatures. The fact that using Range Mode increases battery temperature supports that.
Tesla actually keeps track of this precisely. The BMS measures and keeps track of the entire amount of energy the car has use in it's life. But it keeps track of energy amount charged and discharged separately. This allows one to determine the round trip efficiency of the battery.
What does that mean for range? When the battery is charged fully, the BMS takes the total capacity and divides it by the rated consumption and this gives you the rated range. In normal driving you will have 2.5% losses that occurs over the entire time of the discharge. It means you end up getting 2.5% less range. This definitely confirms the data @supratachophobia has collected.