How many kw hrs am I using?

[ontariomonkey]

Would someone be so kind as to tell me how to figure out how many kw hrs I am using either on each trip or in total (like weekly or monthly or whatever).

I am estimating that each bar of power is 2 kwH (2x12=24) and I could just keep track of that I suppose. I need to figure out how much power to write off for my taxes.

Please keep it simple and step by step please please please. I have no idea how you guys are getting so much info from carwings, I am not even sure I've ever been in carwings.

Cheers!

 

[Randy]

I have a separate meter for my LEAF and keep track of the mileage on a monthly basis to compare with the electrical usage. It varies by month and probably temperature, but 3.3 to 3.4 miles per kWh consumed from the wall is probably a good average for me...

Randy

 

[TNleaf]

Easiest way to figure how many kWh you've used would be to have a meter installed on your EVSE. (This would capture your total usage from the utility)

An easy way to estimate would be before you start a trip, reset the NAV or center console economy and reset one of your trip meters.

At the end of your trip, record both the economy and the mileage.

Example:
Reset Trip A
Reset Economy
<Trip Begins>
<Trip End>
Record mileage from Trip A (ex: 50 miles)
Record Economy (ex: 4 miles/ kWh)

Mileage / Economy = kWh used from the car
(50 miles) / (4 miles/kWh) = 12.5 kWh used from the car

 

[Stanton]

The simple answer is get on CarWings: it's provided for free so use it! While it may not be 100% accurate (maybe off a couple of percent), all the data you seek is easy to read by day/month/year.

 

[HighDesertDriver]

You should have been able to set up your CARWINGS account about the same time you received an estimated delivery date (not month). With that information from you, your dealer should have set up your Leaf with that info during delivery, but you can do it yourself through the menu system.

Assuming you have been pressing "accept" when you first turn on your car, the info should be getting to Nissan and be available to you through CARWINGS.

Go to the CARWINGS address, https://www.nissanusa.com/owners/login" onclick="window.open(this.href);return false;, and log in. At the bottom of the page in small yellow print you will find ">Launch CARWINGS". Click on this, and then at the next page click on the "Driving History" tab. You will find your daily and monthly kWh usage, drive times, etc. here. With a bit more browsing (an exercise left to the student ) you will find where you can download this information.

The problem with using CARWINGS data is that it reflects only what the car is using, not what you paid the electric company for the power to charge your Leaf. For the full story, you will have to install a separate electric meter as TNleaf suggests or a capable monitoring system like TED (http://www.theenergydetective.com" onclick="window.open(this.href);return false. TED is probably your less expensive option and provides a wealth of additional valuable information.

 

[ontariomonkey]

Thank you guys. Yes it seems that I definitely have not been using carwings, I will see about getting that set up. Also using the km/kWh idea is great, I already keep track of the mileage so it is just one more thing. A separate meter is a great idea but I really don't want to put any more money into this EV situation. I just found out that my insurance doubled with this new car! Oh brother.

 

[lpickup]

As has been said, using the in-car equipment or Carwings will not yield your actual electricity use. You will need to account for losses in the charging system and batteries. As has been suggested, you could get some add-on equipment to meter your use, which understandably you don't want to spend money on.

But there are 1 or 2 other simple (and free) methods:

1) Your EVSE may have a meter built into it. See if that's the case first. If so, you're all set! Even my Aerovironment EVSE has metering capability and I can log onto their web site and see exactly how much power it is using from the wall. Granted, it may be a special unit because I'm in a pilot program through my utility so they needed extra monitoring equipment.

2) The other method is to just assume a loss factor. Once you go through the math (or check on Carwings) to determine how much kWh the car thinks it used, you would then divide by that loss factor to determine how much you used from the wall. The usual loss factor for L2 charging quoted is 85%, so for example if you determined you used 18.0 kWh, you would divide by 0.85 and get 21.2 kWh from the wall.

I recently did a fairly controlled experiment to determine my own factor, and while the accuracy available from the car/Carwings is pretty low, it does give a reasonably good figure. Here is my data:

Miles driven: 117.5
Car efficiency meter reading: 4.4 mi/kWh
Consumed power from the car's info: (117.5 / 4.4 = 27 kWh; actually considering it could have been anywhere from 4.35 to 4.45 mi/kWh, the range is actually 26.4 to 27.0 kWh)
Actual power usage from the EVSE (two charging events): (13.83 kWh + 18.77 kWh = 32.6 kWh)
Loss factor = 27 kWh / 32.6 kWh = 83% (calculating the range, it's between 81.0% and 82.9%)

One of the two charging events was a 100% charge, so it's going to be less efficient due to the taper-off in charging, while the battery fan still runs, causing overall less efficiency. But since I sometimes charge to 100%, I think it's fair to include that as part of my measurement. This would account for the fact that my loss factor is less than the 85% usually quoted.

 

[planet4ever]

I am estimating that each bar of power is 2 kwH (2x12=24)

There are quite a few problems with that approach:

1. Nissan advertises a total capacity of 24 kWh, but in order to prolong battery life the car won't let you use that much. You can maybe use up to 21 kWh in warm weather, more like 19 kWh at freezing temperature.
2. As the battery ages its capacity will go down, but "full" will still be 12 bars, so each bar will "hold less electricity".
3. The battery isn't empty when you get to zero bars. You probably have 10% to 15% of its capacity left then.
4. The precision is very low. An apparent drop of two bars could actually be the amount of electricity normally represented by 1.1 bars or 2.9 bars.
5. The bars don't even all represent the same amount of electricity.
6. As others have said, there are significant losses in charging and some in battery storage, so this won't tell you how much electricity you are buying.

Ray

 

[DeaneG]

Could you just use the IRS standard rate per mile instead? Let them catch up with EV-specific costs on their own time. Plus, who can say what Leaf depreciation will amount to.

Oops, maybe you are in Canada rather than California. Which Ontario are you located in?

One other approximate solution is to keep track of your business travel distance, and multiply it by about 0.3 (if in miles) or aboot 0.18 (if in km) to arrive at a kWh consumption equivalent.