Measuring the Total Energy Consumption of Your EV

[tezco]

Continuing to gather a few more data points:

 

[tezco]

I finally got the upgrade notice to migrate from 1.15.14 to v4.2 yesterday. Upgraded this afternoon. You'd think with all those bells and whistles going off during the upgrade process that there might be an increased energy drain from the battery, but check out the pink square on the graph (which is today's idle power usage). Not significantly different from the rest of the data points.

 

[neroden]

Thanks very much for all of this information. I've been trying to estimate expected electricity bills (without installing all the extra metering you installed), and this is giving me a good basis for estimating. (You live in a similar enough climate.)

 

[tezco]

Thanks for the feedback. My mileage graph are really variable and hard to predict--dependent on how much lead foot, how much heater use, how long the battery pack cools down between the two halves of a trip etc.

 

[neroden]

It's the idle power loss estimates which are most useful. The idle power losses are very high; I do hope that Tesla gets sleep mode fixed.

 

[tezco]

Latest data points show higher idle power losses with firmware v4.2 (1.19.42)

 

[Monto]

I just got my car and did not plug in the first night since I wanted to see the vampire load. It started at 100 miles left when I parked and was down to 94 in the morning. 6 X 300w is about 2kW. Then the next day I stopped at a charging station and took 10.8kW partial charge while I was at an appointment. When I got home I plugged in. The next morning it said it took 34kWh to top off the car. The trip meter was at zero to start and read 34.8kWh total energy used. It seems like I put in 10kW more than I used. Even with the 2 kW from the night before, I lost an additional 8 kW somewhere. Is that right? Where did it go?

 

[gregincal]

I just got my car and did not plug in the first night since I wanted to see the vampire load. It started at 100 miles left when I parked and was down to 94 in the morning. 6 X 300w is about 2kW. Then the next day I stopped at a charging station and took 10.8kW partial charge while I was at an appointment. When I got home I plugged in. The next morning it said it took 34kWh to top off the car. The trip meter was at zero to start and read 34.8kWh total energy used. It seems like I put in 10kW more than I used. Even with the 2 kW from the night before, I lost an additional 8 kW somewhere. Is that right? Where did it go?

The car continued to lose energy. You got 2kWh overnight, but probably 3kWh per day. Since you are talking about 2 days that accounts for 6 of your 10 kWh wasted power. The rest was probably charging loss (it takes more energy to replace the used kWh because the charger isn't 100% efficient).

For me, if I leave the car in the garage for the day I get a pretty consistent 3.5kWh charge each night. If I drive to work I use about 19kWh according to the car, but it takes about 25-26kWh to recharge. I figure 3.5kWh is the vampire loss, so I get about 22kWh to replace the 19kWh used driving, or 86% charging efficiency.