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

It has been two months since I got Leaf - and after a modest 1,000 miles on the odometere I propose that both Leaf & Carwings Miles / KWh are wrong.

We have has these assumptions in this forum for a while now
- Carwings m/kwh numbers are too optimistic and wrong (acknowledged by Leaf CS)
- Leaf has 24 kwh usable battery
- Leaf dashboard m/kwh is correct (somewhat unstated)

I've been collecting stats for almost 2 months now. We have also had many others posting their observations and stats. From all these we now have
- M/KWh reported by Leaf & by Carwings
- Miles traveled reported by Leaf & by Carwings
- KWh consumption at the wall reported by Blink/TED/kill-a-watt

The above three need to agree with each other and with the assumptions stated above. They don't.

- We already know that Carings m/kwh is too high. So, let us ignore that.
- We already know that Leaf reported Miles traveled and what Carwings reports are slightly different. Possibly due to GPS being less accurate. Let us ignore this difference.
- Leaf reports m/kwh in two ways. On the dash and on the central console. They are slightly different. The difference is explained by the difference in the mileage reported by Leaf dash & carwings. We can ignore this difference.

But we can't ignore the following.
- Reports of miles traveled divided by m/kwh reported when the battery is almost out (Turtle or near turtle), only give about 20 or 21 KWh.
- People are consistantly reporting above 4 m/kwh. If our assumption of 24 kwh battery is correct, we should be hearing a lot of above 100 miles of range achieved. But, we have almost never heard of anyone getting above 100 miles of range on one charge, though a lot of people have hit turtle and with better than 4 m/kwh efficiency reported by Leaf.

This can only mean one of 2 things.
i. Leaf battery's usable capacity is no more than 21 KWh OR
ii. M/KWh reported by Leaf is also bloated.

One interested aspect was brought up by bowthom.
- Take electricity consumption reported by Carwings (motor + accessories)
- Look at the electricity consumption reported by Blink
- They are in fine agreement (within about 90%, as one would expect)
- Using this electricity consumption and the reported miles traveled, I seem to get more reasonable m/kwh, mainly below 4 as I expect in this cold weather and above 4 a couple of times. 10% to 20% less than what Leaf reports.

What this means is that M/KWh reported by Leaf is also bloated (ii above). There is still a possibililty that i above is correct i.e. Leaf battery's usable capacity is no more than 21 KWh.

Pre or post ECU update numbers?

nader said:

Pre or post ECU update numbers?

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Is there a difference ?

We have only heard about estimated range differences - not m/kwh calculation.

What sort of mi/AC-KWh figures are you seeing using Blink/Kill-a-Watt readings and the car's odometer?
I almost don't care what the car reports (though nice if it was accurate) unless it's measured in what I pay for: AC kilowatt-hours.

DeaneG said:

What sort of mi/AC-KWh figures are you seeing using Blink/Kill-a-Watt readings and the car's odometer?

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Between 3 & 4.2.

Disappointing and kind of basic to get these numbers right. Perhaps marketing overruled engineering and plumped the numbers a bit. The third generation Prius is 5-7% high on the MPG readings (both reported on Priuschat and proven by my brother who kept meticulous notes to the thousandth of a gallon of all the fuel used for 10,000 miles). Also, if they have known about this carwings bug for quite some time, why hasn't it been fixed? What's the point of having these figure if they are wrong???

On the other hand, if the Leaf doesn't really have 24 KWH usable, then Nissan is guilty of false advertising. Any way you slice it, not a class act.

The Energy Screen on the center console (Nav screen) shows the average miles/kWh since the last "Reset" (a touch button on that same screen).

The dash-cluster can show an average miles/kWh, but it does not seem to change much, and does NOT match the value shown on the Energy screen. Watch both and Reset the one on the Energy Screen.

What resets the one in the instrument cluster?

garygid said:

What resets the one in the instrument cluster?

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The buttons to the left of the steering wheel on the dashboard.

LEAFer said:

garygid said:

What resets the one in the instrument cluster?

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The buttons to the left of the steering wheel on the dashboard.

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Specifically, the upper right of the four buttons is the reset for the various center dash displays.

I've suggested a couple of times in other threads, with no response, that miles/kWh on the Energy screen may be based on plus and minus energy flow through the motor rather than energy flow in and out of the battery. It seems to me to be a logical thing to do as it would then be stating the efficiency of the power train without being masked by aux uses such as heater, A/C, or lights. It would also help explain the discrepancies evnow has pointed out.

Ray

planet4ever said:

I've suggested a couple of times in other threads, with no response, that miles/kWh on the Energy screen may be based on plus and minus energy flow through the motor rather than energy flow in and out of the battery. It seems to me to be a logical thing to do as it would then be stating the efficiency of the power train without being masked by aux uses such as heater, A/C, or lights. It would also help explain the discrepancies evnow has pointed out.

Click to expand...

But on a daily basis the use of heater affects my m/kwh. I usually get above 4 if I don't use heater and below 4 when I do.

Be careful!! When isuggested that we did not have 24 kwh two months ago they started heating up the tar and plucking chickens!

Hello,
I have a nice nifty excel sheet with all my carwings and blink data correlated on a daily basis for the month of April. When both carwings and blink are reporting it does line up pretty well using the "consumed" figure. Unfortunately there are times when I don't get emails from carwings or the Leaf starts cycling the charger over & over. Also times when the blink fails to report a charge or reports it as zero kWh. I send my sheet to blink with all the reporting problems highlighted so they can look into what is happening. The report that is generated at blink (seen by their operators) has separate columns for |plug-in | unplug | charge start | charge stop | power events|.




I was in fact NOT charging, the leaf was sitting at work.
The last line should be 8.8 kWh not zero

I had posted this a while ago, but think this might be useful here:

Some "inside" person at Nissan told me that the total battery capacity is 24 kWH of which 20 kWH are used for driving.
This is consistent with my observations so far and it looks like its also consistent with what others report. Nissan
has been sort of hedging, when pressed about the battery capacity, not sure why.

The problem with driving the car empty and then checking how much kWH a full charge takes with "conventional" methods, e.g. using a kill-a-Watt and the trickle charger or Blink is that this just measures how much AC energy went in. In order to get at the "true" battery cap, one would have to measure the DC power that the charger provides. Stopping the time how much it takes to charge and assuming it is indeed 3.3 kW would work?
Anyway, my experience from our PV system, which is not directly grid tied but goes via batteries, is that between DC to AC grid conversion you get about 85%, and that is without the charge efficiency of the Lion battery. I.e. ~15% are just lost in the charge controller and the inverter.

I just checked my April numbers....


Blink reports 507.47kWh used.
TED reports 503.931kWh used.
Carwings reports 302.4kWh used.

Blink and Ted are <1 % different. Carwings is 40% different. I know Carwings 'adds' the regen energy, but 40%????

Guys, keep in mind the battery is not a "perfect tank" like a gas tank is. There is a phenomenon called "Peukert's Law" that allows a mathematical model to constructed of the battery to show how this non-linearity works.

Basically, the less you draw current from a battery, the less is wasted in internal heating. If you draw high currents (such as an EV does), a lot of "usable" capacity is burnt off as heat in the pack. This means if you drive at 10mph, you might get closer to the actual "usable" capacity, but if you drive at 70mph, you'll get a huge loss of capacity.

Now, the LEAF's Battery ECU maintains an internal calculation of each cell's internal resistance, so it's possible for it to calculate all this and provide you with a corrected calculation of energy consumption, and range estimation, but clearly this would take more work.

The energy consumption is measured between the battery and the car electronics, (current shunt) so it doesn't include loss in the battery.

-Phil

I drive pretty conservatively with most driving under 45 mph.

My very rough calculations say I can use around 21.4-21.8 kwh

I charged exclusively at 120 with killawatt so know exactly what went in...so there no question on that.

DaveinOlyWA said:

I drive pretty conservatively with most driving under 45 mph.

My very rough calculations say I can use around 21.4-21.8 kwh

I charged exclusively at 120 with killawatt so know exactly what went in...so there no question on that.

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I would assume the LEAF's on-board charger is somewhere from 80%-90% efficient. I seriously doubt it's over 90%! So take that into account as well. The energy going in is always more than coming out!

-Phil

My estimates of effciency is between 80-86%.

For reasons I am not sure of. The effi iency seems to be somewhat better when the weather is warmer. Was seeing #'s suffering an efficiency in the mid 70's...

I was already thinking to start a similar topic regarding confusing m/kwh readings.
I even took a photo of the dash board yesterday that shows typical picture (at least after the software update):



After inititial 80% charge and driving for two days, I ended up with my usual near 5 miles per kwh.

As you can see my total would-be range is short of 75 miles on 80% charge.

That gives me just 15 kwh of used battery. After adding 20%, it is freaking 18 kwh for the whole pack!
Not even 21 or 20 what others reporting here.
Where are the rest 6 kwh?
It is definitely something very wrong either with capacity or with the average economy reading.

I would appreciate guys if you give me any reasonable explanation.

And today after another 80% charge, I see usual overly optimistic 93 miles in ECO mode which is going to drop like a rock after a few lost SOC bars.