Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24 KWh

[Coffee_Slurry]

Those of us with a Second Meter for the EVSE should be able to get perfectly accurate long-term data.

Odometer in the car & EVSE kWh consumption.
What else is there to know?
That, with your power bill, has the most irrefutable unfudgable data on what the car costs per mile, and how much power it uses overall.

Trying to break it down further into Charger consumption vs Battery consumption, driving habits, and so on will always introduce some unknowns. But cost and mileage are absolute.

 

[evnow]

Here is another data point. Everyone with a separate meter (or kill-a-watt) can try this.

First use a timer to charge Leaf to 80%. If you are using Blink, note the monthly KWh consumed.
Then, charge again by either disabling timer or as I did, through the web. Note the Kwh consumed.

This method gave me 5.1 Kwh of energy consumed to go from 80% to 100%.

Here is the table showing various charging efficiencies and resulting assumed battery capacity.

Modern battery chargers have high efficiency - above 85%. I see numbers between 85% and 90% mentioned in various places (with some new charging methods claiming more). This places the Leaf battery capacity (allowed to be charged) in the range of 21.5 to 23 kwh.

BTW, the change/discharge round trip efficiency for Lithium battery is very high. I saw several mentions of 99%.So, in practical terms, what you put into a Li battery is what you get out. The losses are mainly in the charger, inverter, controller and the motor. Mains to wheels efficiency is about 75%.

 

[Smidge204]

What guarantee do you have that when the car stops charging at 80% that the battery is actually at 80% and not, say, 81% or 79%? It is also possible that the average efficiency from 80%-100% is not the same as 0%-80%.

The problem so far is that nearly all the attempts to independently verify battery capacity rely on the car's internal programming to provide at least some of the information. There are heaps of evidence to suggest this programming is not to be trusted, therefore any conclusions you reach about battery capacity that rely on it is suspect.

The only way you will know for sure is you disassemble the battery pack and examine the individual packs within, or install your own calibrated DC power metering between the charger and battery. A slightly less reliable method would be to drive it until it is absolutely 100% dead (like what Edmunds did) and fully charge it, measure the power from the wall and then see if the numbers are reasonable... you'll still have to make a few inferences but it's a lot easier.
=Smidge=

 

[evnow]

What guarantee do you have that when the car stops charging at 80% that the battery is actually at 80% and not, say, 81% or 79%? It is also possible that the average efficiency from 80%-100% is not the same as 0%-80%.

Given that the efficiency itself is not known and we are considering a wide range, a slight diviation from 80% will not add much to that variability. Check the numbers using 79% or 81%, you will see what I mean.

The avg efficiency for a battery from 0% to 80% is likely not the same as from 80% to 100%. 80% to 100% is lower. But then, we aren't really talking about "real" 100%, but 100% of the allowed capacity. If the efficiency in the region we are charging is lower (say 80%), then the capacity is lower at about 20.5 kwh as shown.

 

[starry]

Finished charging to 100%, as shown by Carwings. That may be about 80% of battery capacity. Car showed expected range of about 82 miles. House electric meter shows 24Kwh used while charging in period 645pm to 630am or about 12 hours. My daily use is almost 17Kwh last month. That includes some house fan, refridge, lights, wallwarts, TV, computers. Only about 18 hours from car in April. Given my poor math skills, I would say that the car was 5/6ths discharged (indicated 2 bars or 17 miles range after trip of about 62 miles), then the empty part of battery capacity would have been about 20Kwh. The fact that 24Kwh was used during the charging period is about right after subtracting about 4Kwh for house use in the lowest draw overnight hours. Cost for that 5/6th charge was 20Kwh x $0.27/Kwh in "Tier3" of SDG&E billing rates for $5.40 cost of charging car. That covered a 62 mile trip. That is an 8.7 cents per mile cost. It is quite a bit less than my 1993 minivan cost of 19.76 cents per mile for gasoline.
Gregg

 

[thankyouOB]

how much of these calcs about battery usage and miles/kWh are thrown off by the unknown factor of regenerative add to the pack?

I don't now of anywhere that is calculated except on the web-based car wings tools you access through leaf account with nissanowner.

 

[evnow]

how much of these calcs about battery usage and miles/kWh are thrown off by the unknown factor of regenerative add to the pack?

I don't now of anywhere that is calculated except on the web-based car wings tools you access through leaf account with nissanowner.

We don't know how m/kwh is calculated in the Leaf dash/console. It should be based on net energy output from the battery i.e. energy out - energy in from regen.

Carwings seems to use too much of regen to reduce kwh used, resulting in bloated m/kwh. If only 40% of the regen reported by Carwings is used to calculate m/kwh, carwings figure will match that of Leaf console.

 

[gbshaun]

how much of these calcs about battery usage and miles/kWh are thrown off by the unknown factor of regenerative add to the pack?

I don't now of anywhere that is calculated except on the web-based car wings tools you access through leaf account with nissanowner.

We don't know how m/kwh is calculated in the Leaf dash/console. It should be based on net energy output from the battery i.e. energy out - energy in from regen.

Carwings seems to use too much of regen to reduce kwh used, resulting in bloated m/kwh. If only 40% of the regen reported by Carwings is used to calculate m/kwh, carwings figure will match that of Leaf console.

Remember, regen can only happen when there is a prior, or subsequent, additional draw. ie either you just powered up a hill and are now breaking going down, or it was a dip in the road, or you had to slow (traffic, stop sign, red light etc) and will have to accelerate back up to speed. The energy recouped will always be less than the extra energy used, but at least now we get something back ! Maybe Carwings doesn't take into account the losses involved in the process. Sounds like it need an update.

 

[DaveinOlyWA]

ok, let me go back a bit.

first of all what i do know or can verify with high assurance of accuracy and that is how far i went and how much power went in from the wall. using Killawatt which is listed as much greater than 99% accurate. so will consider that figure to be indisputable.

so i also am recording what the car states its using from the energy screen for its MPK figures.

it is over optimistic but is the only real measure of battery used. so would have to assume that removing the power that accessories used would give us that figure, but accessories still use power and is controlled by us like any other external option like heat, speed, etc.

so if assuming the charger is 90% efficient, then we would have to say any other discrepancy would be due to power being used to cool the charging process.

now, we have several reports using various sources for figures that say the efficiency is running from 80 to 90+%. the most seem to be in the 85% range.

mine has become relatively stable at 75%. i am using 120 which is apparently a penalty. i am guessing this penalty is due to the cooling process which may not be tied to the amount of heat generated making any longer time to charge a set use per unit time and unrelated to the amount of heat produced during the charging process.

so if charging at 120 volts taking twice as much time, it would correlate that my efficieny drop would be about double that of someone charging at 240 volts. so instead of getting 85% efficiency at 240 which is 5% less, i am getting 15% less efficient at 120 volts.

wondering since the charge rate drops for the last hour or so, that if avoiding that part of the charge cycle would increase anyones #'s?

it would have been nice for Nissan to have advised us that 120 was a much less efficient use of power

 

[edatoakrun]

it would have been nice for Nissan to have advised us that 120 was a much less efficient use of power

Couldn't this be easily verified by one of the 240 v crowd doing one or more monitored 120 volt charges, for comparison?

If the 120 v efficiency is this much lower, it should be apparent.

 

[evnow]

it would have been nice for Nissan to have advised us that 120 was a much less efficient use of power

Couldn't this be easily verified by one of the 240 v crowd doing one or more monitored 120 volt charges, for comparison?

If the 120 v efficiency is this much lower, it should be apparent.

I'll do it one of these days. Just that I don't want to lose the easy stats I get out of Blink now ...

 

[MrFish]

Last night I ran all the way to battery cut off (had to push the car up the driveway) and I recharged with L1 and a Killawatt meter. It required 27.65 kw AC to charge to 100% from dead, so it is safe to say that there was around 24kw available from the battery pack, even with a 88% charging efficiency.
I did have the software update 2 weeks ago.

 

[DaveinOlyWA]

27.65 is just over a kwh more than people report on 240.

Ah were it tone that easy. What was the temperature when u were charging? . Unfortunately all that will hangs battery capacity some.

But the contention I have is that 24 kwh was not replaced

 

[awolfe63]

Has anyone taken this up with a dealer? There must be a battery capacity diagnostic that they can run.

My best estimate is that I am only getting 18-19KWH usable. I'm trying to get Nissan to verify this.

 

[DaveinOlyWA]

Has anyone taken this up with a dealer? There must be a battery capacity diagnostic that they can run.

My best estimate is that I am only getting 18-19KWH usable. I'm trying to get Nissan to verify this.

this appears to be a corporate secret we may not be privy to. now some have reported 24 kwh on diagnostic equipment used by Leaf techs but like...who knows?

 

[evnow]

My best estimate is that I am only getting 18-19KWH usable. I'm trying to get Nissan to verify this.

How did you come up with that figure ?

 

[EVDRIVER]

Has anyone taken this up with a dealer? There must be a battery capacity diagnostic that they can run.

My best estimate is that I am only getting 18-19KWH usable. I'm trying to get Nissan to verify this.

this appears to be a corporate secret we may not be privy to. now some have reported 24 kwh on diagnostic equipment used by Leaf techs but like...who knows?

It is 27kwh in the system based on the ah rating not 24kwh. This means a potential of 27kwh.

 

[evnow]

It is 27kwh in the system based on the ah rating not 24kwh. This means a potential of 27kwh.

Interestingly 80% of 27 = 21.6 kwh. Agrees nicely with our other data.

 

[awolfe63]

My best estimate is that I am only getting 18-19KWH usable. I'm trying to get Nissan to verify this.

How did you come up with that figure ?

The in-car reported miles/KWh over a long test period is 3.8 miles/kwh. Average distance over a wide variety of trips over the same period, I seem to be averaging 5.5-6 miles/bar. This works out to ~1.5KWh/bar.

Charging times roughly correspond to this number. About 30 min/bar each night. (at 3.3KW from the wall)

Admittedly rather rough - but rather than me trying to devise a better experiment, I'm certain that Nissan has build in monitoring and measurement software that they can access.

 

[evnow]

Admittedly rather rough - but rather than me trying to devise a better experiment, I'm certain that Nissan has build in monitoring and measurement software that they can access.

Yes rough. You can see the first post of this thread why I think it may be less than 24 kwh.

Ofcourse Nissan knows exactly how much they use - they designed this. They don't want to talk about it. When I chatted with Mark Perry, he deftly dodged the question & I didn't press.