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

[DaveinOlyWA]

And then we have the charger cooler that needs to run consuming some power when charging (which doesn't make it to the battery).

ps : The life time m/kwh of wall and Leaf I show in my sig comes to 76%. Hmmm ....

i had reported that i might be improving from my originally reported 75% due to possible weather changes, but it was just an anomaly caused by only occasionally going to full charge. i am getting a pretty consistent narrow range of results that run from 75-77% so it would appear that there is no significant difference in charger performance efficiency-wise from 120 to 240.

move date is set to June 8th. wont really be settled for at least a week. hope to have a 240 option for my mod EVSE. but will be unable to track its performance or amount of charge.

anyone find a relatively cheap option for that? looking at ~ $50

 

[ERG4ALL]

Evnow wrote:

As for Nissan, they have always said the total capacity of the battery is 24 kwh with Leaf using a very high % of that (the % varies from media to media). Mark Perry told me Leaf has a 24 kwh total capacity battery, he wouldn't tell me how much of it is useable. Infact saying Leaf has 24 kwh usable goes against what Nissan has been saying.

When you are concerned about usable energy from the battery, I presumed (apparently mistakenly) that the concern was the range that could be achieved with that usable energy, otherwise why are we interested? I'd still be interested in anyone that would perform the LA4 test, read the remaining energy in the battery, and then extrapolate that into the claimed 100 mile range.

 

[edatoakrun]

Now that I Finally have my LEAF, I'm also trying to run down the lower efficiency rate for L1 charging and total battery capacity questions on this thread.

On Tuesday night I recharged at the Sierra Nevada Brewery, Chico CA (Many thanks, and my nominee for "official beer of MLN") chargepoint.

From my previous full charge at (edit) Davis Nissan, my LEAF went to 2 bars at about 82 miles, and had still had both after another 8 miles at about 55 mph, for 90 miles total. I restarted to check the numbers just before plugging in, and only 1 bar then showed. Charging took 5 hours and fifteen minutes. I didn't see a total charge number, but the charger reported constant kWh that only seemed to range from 3.696-3.702, so I believe my reported total charge was very close to 19.425 kWh. (edit-Chargepoint reports I got 19.601 kWh)

I planned to make the final 87 hour trip home on this charge. But my bars/range didn't last nearly as long, I expect due to lights, wipers, and (possibly) the high winds and heavy rain. So I detoured to Redding, adding about 10 miles to my trip, and got about 2 hours ( and went from 2 to 6 bars) of L2.

I am very glad I did. I left Redding with 49 miles and six bars, for a 28 mile trip, but in just the final 10 miles with 1500 feet of climb I lost 3 bars, going to 1 bar about a mile before I got home, with only 5 miles of range remaining when I got home-and no warnings. After recharging to 100%, My range display now shows only 32 miles, if that is useful info to anyone. It certainly proves to me how useless LEAF "range estimates" are if you drive in the hills.

It took 19 and a half hours to recharge, 23. 81 kWh as measured by kill-owatt. It's not practical for me to get much closer to empty, so this is about all the info I can contribute. All indications, to me, are that I had very close to identical levels of discharge (if bars are to be believed) and it took about 20% more kWh to charge the same car (albeit probably at lower battery temperature,about the same average ambient temperature) at L1 as opposed to L2.

Why is 120 so inefficient? Can it be that the water pump (it seems to run constantly while charging for me) and other loads consume much more power for the much longer charging session? As to DaveinOlyWA's question, I also plan to use Ingineer's modified EVSE for all charging. anyone been able to track it's efficiency? If efficiency is mostly a function of charge time, wouldn't it be far more efficient than the supplied L1, but less efficient than a 16 amp L2? Anyone checked?

 

[gbarry42]

Looks to me like the way to get to the bottom of this charge efficiency thing is to capture all losses while charging is in progress. Since all losses will eventually appear as heat somewhere, all we need to do is place the vehicle in a thermally insulated tank of water and measure the temperature rise at the end of the charge cycle. All you need to know is the mass of the water, and convert calories back into kilowatt-hours, and :ugeek: presto...we have our answer. Since my garage is a tad to small, and April 1 has passed, I may have to leave this experiment and accompanying fame to someone else.

In the interest of keeping all the nonsense in a single message, I also offer this: Rumor has it that at least one of the rebates (Federal, maybe?) is based on the kWh capacity of the battery pack. This is allegedly how they got the Volt to qualify as being an EV. If this is true, I would expect that there would be an official document somewhere with a declaration by Nissan Motor Company as to the true pack capacity. Assuming they were honest, and that they were required to report the figure we are hoping to find. And that the premise is more than a rumor.

 

[DarkStar]

FYI: We have purchased (and sold) all of Nissan's remaining stock of EVSE's in North America, so they are now on national backorder from Japan. Word is end of the month before we get the next shipment.

Yep, you should just go direct to Panasonic!

 

[LEAFer]

...

On Tuesday night I recharged at the Sierra Nevada Brewery, Chico CA (Many thanks, and my nominee for "official beer of MLN") chargepoint.

...

All indications, to me, are that I had very close to identical levels of discharge (if bars are to be believed) ...

Interesting trip data, Ed. Thanks for that.

I don't know if you have a ChargePoint account and used it at the Brewery, but if you did, you can login and get an accurate accounting of how many kWh's were used.

 

[DaveinOlyWA]

well if we make the assumption that the amount of power devoted to cooling is relatively static between 120 and 240, then we need to guesstimate as to how much power is used to circulate the water. the monitoring system would be the same so if we are taking 86% for charger efficiency, then we are looking at say...8-10% for cooling.

so i would have to say since there is no evidence that there is that much of a difference between the 120 and the 240 (although we really need more people chiming in with their 240 volt figures to know for certain)

i kinda have to assume that 120 volt charging is slightly more efficient but that improvement is lost due to the additional time to charge and the static overhead power used for the approx 120-130% greater charge time.

now, i have rarely charged to 100%. only once in the past 2 months. so my efficiency would be higher due to charging at full power? since the end of the charge cycle lowers the charge rate which increases the impact of the static cooling power penalty?

so 120 could be at the low 70% range were i to fully charge? i feel this to be the cause of my small bump in efficiency.

 

[edatoakrun]

...

On Tuesday night I recharged at the Sierra Nevada Brewery, Chico CA (Many thanks, and my nominee for "official beer of MLN") chargepoint.

...

All indications, to me, are that I had very close to identical levels of discharge (if bars are to be believed) ...

Interesting trip data, Ed. Thanks for that.

I don't know if you have a ChargePoint account and used it at the Brewery, but if you did, you can login and get an accurate accounting of how many kWh's were used.

Thanks LEAFer- I just checked, Chargepoint reports I used 19.601 kWh

As to Sierra Nevada Brewery, I was told the owner has a LEAF on order, but only "about ten" EV's had used the charger, so far. There is a restaurant and pub with a theatre upstairs, if anyone wishes to catch Dinner and a show-with a recharge. There is also a brewary tour, but I got there too late, and I believe you have to make reservations, so I could only wander around public areas of the brewery-some very interesting displays.

The 2 L2 chargers are posted as public, though chargepoint seems to say one is restricted. Maybe the owner plans to keep it private, once he (and other employees?) have their cars?

I felt a little guilty taking a full charge. I promise the owner I intend to make it up to him, in future liquid fuel purchases.

http://www.sierranevada.com/index2.html

 

[evnow]

ps : The life time m/kwh of wall and Leaf I show in my sig comes to 76%. Hmmm ....

i had reported that i might be improving from my originally reported 75% due to possible weather changes, but it was just an anomaly caused by only occasionally going to full charge. i am getting a pretty consistent narrow range of results that run from 75-77% so it would appear that there is no significant difference in charger performance efficiency-wise from 120 to 240.

I think there is some problem with my lifetime stats - either I didn't note down everything correctly or blink played some tricks. I get between 80% and 90% between m/kwh at the wall and what Leaf reports.

Earlier I used to go by memory about the m/kwh and miles driven that Leaf showed. Now I record that on my phone everyday - so it is much more accurate now.

 

[DaveinOlyWA]

I think there is some problem with my lifetime stats - either I didn't note down everything correctly or blink played some tricks. I get between 80% and 90% between m/kwh at the wall and what Leaf reports.

Earlier I used to go by memory about the m/kwh and miles driven that Leaf showed. Now I record that on my phone everyday - so it is much more accurate now.

do you have updated stats? that is the reason i started reporting MTD figures for MPK. they are changing rapidly with the change in season. granted our "change" has only begun and we still have not had any real warm weather. (i will take this week all year!! but a bit cooler than most would want)

 

[bowthom]

Hello,
I'm not seeing much difference yet. It's 60* ~ 70* during the day but still in the mid 40's at night when it's charging. I now have 5 bars showing on the battery temp though.

 

[Ingineer]

As for charge efficiency, I'll try to take a measurement soon and get the real numbers.

Battery charge efficiency typically increases at lower rates. (this is just the battery itself)

The charger internally probably has a "sweet spot" where it's most efficient, and they usually optimize for the higher side, so I would side with 240v being slightly more efficient.

However, the white elephant is the charging overhead. The coolant pump, the ECU's, the main contactor, etc. all drain a fixed amount, so the faster you charge, the lower % wise this fixed load is.

-Phil

 

[gbarry42]

I wonder if you can fiddle with the pilot signal, and reduce the charge to the point where there's little or no charging going on. Then, the measured power input would be all overhead. Simpler than my other experiment, anyway

 

[Ingineer]

I wonder if you can fiddle with the pilot signal, and reduce the charge to the point where there's little or no charging going on. Then, the measured power input would be all overhead. Simpler than my other experiment, anyway

It's far easier just to measure the current at the battery with a clamp-on DC amp probe, and then compare that to the power going in at 120v and then at 240v. All we care about is total systemic efficiency, although it would be easy to also measure the DC output at the charger but before the DC-DC converter, which would show the overhead on the 12v system just for curiosity.

-Phil

 

[planet4ever]

Rumor has it that at least one of the rebates (Federal, maybe?) is based on the kWh capacity of the battery pack. This is allegedly how they got the Volt to qualify as being an EV. If this is true, I would expect that there would be an official document somewhere with a declaration by Nissan Motor Company as to the true pack capacity. Assuming they were honest, and that they were required to report the figure we are hoping to find. And that the premise is more than a rumor.

Not a rumor. The amount of the federal tax credit (it's not a rebate) is indeed based on the battery capacity. BUT ... It maxes out at $7,500 for 16 kWh. It seems pretty clear that Michigan legislators were heavily involved in creating the formula, and they probably knew how big GM was planning to make its battery. As for Nissan, all they had to do was certify that their capacity was at least 16 kWh. Nothing beyond that mattered.

Ray

 

[bowthom]

Hello,
I am getting what appears to be better efficiency using my Phil modified mini evse. Part of it may the reduced overhead of the smaller unit. At any rate I'm seeing ~ 90%, up from 87% with the blink.

 

[Coffee_Slurry]

It would be great if Nissan would allow entry of some "calibration factors" to tune the system.

Or the Blink, for that matter. Mine is consistently reporting 1.4% low for energy consumption. I'd like to dial that out.

Then I'd like to make a closed-loop with the LEAF to inform it how much power it drew from the tap, and use THAT value to compute Miles/kWh.

Because really, I don't care about the losses before, inside, or coming out of the battery.. I care about what it does to the power meter.

 

[planet4ever]

To tell the truth, I have long doubted the 75% charging efficiency that DaveinOlyWA has been reporting for months, suspecting that there must be something wrong with his methodology. Sorry about that, Dave. I am now becoming a believer.

On Thursday I ran a fairly tightly controlled test, driving three round trips on a country road, using ECO and cruise control set at 45 mph. The speed limit was 45, and traffic was light enough that only once did I have to slow a bit. I stopped at each end of each run to log data, but other than that there were no stops on the run. Climate control off, lights off, audio off.

I won't bore you with all the data, but here is the bottom line for this post:

• Starting condition: Fully charged with unmodified Nissan L1 EVSE, reset trip odometer and m/kWh meter in dash.
• Ending condition: 42.0 miles, 5.0 m/kWh, 7 SoC bars (fifth one lost at 39.9 miles).
• Recharge: To full charge (after 3 charging lights in the car went off), same L1 EVSE through Kill A Watt, 11.04 kWh.

(42.0 miles) / (5.0 m/kWh) = 8.2 kWh
(8.2 kWh) / (11.04 kWh) = 74%

Either Dave's and my Kill A Watts are both grossly inaccurate, or the m/kWh meter in the dash is grossly inaccurate or the charger is grossly inefficient at 120v.

I don't have any way to measure voltage at the wall when charging at 240v, but two nights ago I did closely monitor bars as reported by the Owner's Portal during 240v charging, and my conclusion from the time required below bar 12 (which takes a very long time) was that each bar, at least #7 through #11, represents only about 1.6 kWh at the wall.

On my test run, the first bar lasted longer than the others, but each of the rest was running about 7.8 miles. If I had charged at 240v that presumably would have meant 7.8 / 1.6 = 4.25 m/kWh total usage from the wall, which is 85% charging efficiency when compared to 5.0 m/kWh.

Is there really that much difference between 120v and 240v charging efficiency? edatoakrun seems to think so, and bowthom is reporting even better numbers than I came up with. My numbers for 240v are very rough. We need someone (like Phil) to make some accurate measurements, or at least someone who can measure wall usage both ways to do two comparable runs, one at each voltage, to see what is going on.

If there is a large difference maybe we are discovering the real reason Nissan recommends L1 for occasional use only.

Ray

p.s. The numbers I've thrown out here also have significant implications for total battery capacity, but I'll leave that for another day.

 

[edatoakrun]

The only reasonable explenation I've seen for the (apparent) much lower charging efficiency at L1 is the car's energy consumption during (much longer) charging. Could an owner with a modified EVSE please post results and methodology of their electricity use and charge time, comparing 12 amp 240 to either/both 12 amp 120 and 16 amp 240? Until someone can accurately measure total energy consumed during charging, this might be the best way to estimate.

And it could also, I believe (on topic!) help clear up some of the measurement uncertainties of battery capacity.

 

[evnow]

Here is my scatter chart of Dash / Wall m/kwh vs Wall kwh. As you can see it is all over the place - but larger the amount of charge I put in, the lower the %.

Avg : 83%
Median : 82%