doubts about my efficiency

[sput]

hello all, I am a leaf owner since four weeks ago. I'm checking the kWh used, the miles driven...

From july 1st to july 18th these are my figures:

- I charge it until 80%. This is important, how much kWh do I charge in this situation?. I suppose 80% of 21kWh because nobody knows the total capacity (or usable). So I supose I charge until 16,8 kWh each time.
- total miles 271.7
- total kWh 69.5 (84.1 - 14.6 generated).
- 3.91 miles per kWh.

My last distance was 48.7 mi and 7.5 remaining. It would be a total of 56.2 miles at 80% of charge.

But if you make make calculations, it would be: 3.91 mi/kwh, with 16.8 kwh = theoretically 65.7 mi.

Here is the problem. I suppose I could have done 56.2, but if you look at averages, it must be 65.7 mi. ??!!??

Could you help me?

 

[planet4ever]

First, you can't assume a constant battery capacity like 16.8 kWh. The capacity varies with the temperature of the battery, and probably based on how well the battery controller has "learned" your particular battery. To compound things, Nissan uses an inexpensive and not very accurate measuring tool to keep track of how much electricity is being used. Finally, we suspect that some cars come from the factory with more usable capacity than others.

Second, you really can't depend on "miles remaining" numbers. Those are based on what we call the "GuessOMeter" because a computer in the car is trying to guess how you will be driving in the future. Only you know that! From the numbers you are presenting it would appear that you are looking an information maintained by CarWings. That can provide one more level of rounding errors, delayed updates, and possible misinterpretation of the data.

Finally, a number of us have seen odd results when we have tried to calculate using the m/kWh meter. It is possible that it is less reliable in 2013 cars than in earlier ones.

You might want to watch the battery state of charge meter which is available on one of the screens of the Trip Computer. That's the display in the bottom center of the dashboard, controlled by the four buttons in a square layout between the steering wheel and the door.

Ray

 

[sput]

Hi Ray, and thanks. I have to point out some things:

- I check figures on Carwings. Miles are accurate because I check miles and are the same.
- My Leaf is bought in June'13 but is 2012 model. This is Europe. 2013 model comes now. So I haven't the battery state of charge meter in the display.
- I charge at about an ambient temperature of 75ºF (+/-). I assumed that this was an optimum temperature...

It seems that I'll have to assume that my battery has 18 kWh usable. Far from 21-22 kWh.

(3.91 m/kWh, doing 56 miles at 80% -> 14.3 kWh at 80% -> 17.9 kWh at 100%.)