Wall kWh's used for 0 to 80% charging

[MikeD]

I'm sure this has been mentioned here/there before, but I thought a separate post could be valuable for owners wanting to have an approximate benchmark to compare their own charging experience. This number is readily available to Blink owners as the difference between the Stats screen month's cumulative "Energy(kWh)" for last and just previous charging sessions. It probably would be worthwhile to include the approximate temperature range during charging, particularly for very cold/hot conditions.

If some people have 0 to 100% charging wall kWh statistics, that would be of interest to see as well.

This statistic should be a good indicator of one's current battery pack capacity, I think, and could serve as an early warning of a pack problem if significantly lower than the average new pack value.

 

[Herm]

Since EVSE manufacturers are charging a stupid $1000 for their devices, this is a function that they should provide.

 

[DaveinOlyWA]

i agree. but "general" rule of thumb says if charging with the supplied 120 volt EVSE, you are getting about 75% efficiency. with the 240 Volt 16 amp system getting 85-86% and with the modded EVSE at 12 amps about 81-82%

now that is half the battle. to determine what you are charging, you will have to reset the miles/kwh on your Leaf daily and track daily mileage.

one thing i found out is that the meter on the dash always reads a bit lower than the one on the Nav Display. now part of that i "used" to assume was because it covered a longer period (reset it once a month, the other daily)

but my average on the daily over the month still came out .2 mpk higher

 

[davewill]

...one thing i found out is that the meter on the dash always reads a bit lower than the one on the Nav Display. now part of that i "used" to assume was because it covered a longer period (reset it once a month, the other daily)

but my average on the daily over the month still came out .2 mpk higher

One theory is that the NAV is using the GPS instead of the odometer to measure distance traveled, which has a tendency to "cut corners".

 

[DaveinOlyWA]

...one thing i found out is that the meter on the dash always reads a bit lower than the one on the Nav Display. now part of that i "used" to assume was because it covered a longer period (reset it once a month, the other daily)

but my average on the daily over the month still came out .2 mpk higher

One theory is that the NAV is using the GPS instead of the odometer to measure distance traveled, which has a tendency to "cut corners".

ahhh...hmm. well ok. my theory is that every morning when i reset the NAV meter, it takes about 10 seconds before it starts to record despite its resolution being less than a second.

when moving from a standstill, you will notice a large amount of power used. i see 25 kwh or more even when moving under 15 mph but i can cruise at 25-40 mph at 5-8 kwh. so that means the initial startup is usually inefficient

 

[MikeD]

OK, I would like postings to this thread to concentrate on the NUMBER(s) that I originally requested, and (much) less on tangential issues...

I'm sorry, I should have started my OP with at least one kWh measurement for myself, but I've yet to discharge less than 2 bars. I will be sure to do so in the next 2 days and report back!

Since I understand one can still drive a number of miles after the last SOC bar disappears, I will try to park the car for charging shortly after the last bar disappears in an effort to pinpoint what I mean by charging from 0% to 80% (the latter determined by the Leaf's internal 80% automatic charging cutoff).

Except for temperature (and pressure?) differences, I would expect that the kWh's input from the Blink charger in this situation should be related (by a constant factor?) to the kWh's available to be output from the battery pack (i.e. its capacity) before the last bar disappears.

So, again, it is this kWh's input reported from the Blink charging station to charge from 0% to 80% that I would like interested owners to please post so that an average value can be calculated that can be used as an (indirect) benchmark for normal new battery pack capacity.

 

[DaveinOlyWA]

ok. something like that would be hard to quantify easily.

first; a base line would have to be established. and other than specific # of power circles in turtle mode, it is not really possible. using a general guideline of having a certain bar disappear might work, but would be an inconvenience at best and difficult to find others in the same situation. we all have different driving commutes.

2nd; i am not convinced that 80% charging is a hard stop figure. i believe it only to be a general hit.

3rd; your best bet is to gather as much data as you can by reverse engineering the #'s. i can track charge from the wall but i use a slightly less efficient method with 240 volts @ 12 amps. my efficiency thus far with a week of data is about 82%.

what i can try to do tomorrow is run the car down to a certain level like 2nd low battery warning or something then plug it in and get that.

 

[Boomer23]

My charge from "turtle" to 100% took 26.1 kWh from the wall, measured by my TED system installed in my power panel.

I haven't done a charge from "turtle" to 80% yet. The closest I've come is charging from 1 bar to 80%. That charge took 16.3 kWh. I happen to have a prototype State of Charge meter on loan from garygid et. al., and prior to charging, when the dash read that I had 1 bar remaining, the SOC meter showed 14% of battery charge remaining and 41 out of 281 SOC "counts" or "numbers". Note that I've had the firmware reflash done, so I have "new bars".

You can take this data for what it's worth. Simple math would estimate that if the LEAF took 16.3 kWh from the wall to go from 14% to 80% charge, that each 1% of charge took 0.247 kWh. But for my "turtle" to 100% charge, it took 0.261 kWh per 1% of charge. We know that there is non-linearity in the charge and discharge curves, so this isn't too surprising.

 

[MikeD]

Boomer23: Thanks for your results!

I just finished getting my own charging results. After driving my range remaining down to 3 miles in the immediate neighborhood of my charger, I got the 2nd low charge audible warning and my range remaining was replaced by dashes. I drove a short distance to my charger and connected my Blink, scheduled to begin an 80% charge (after about 90 minutes) at 11:00p. (Note I had driven 73 miles on the previous 80% charge, but the last 5 miles or so had been driven uncharacteristically inefficiently -- driving also with the high beams and the front window defroster on trying to quickly use up the remaining capacity before any neighbors called the police on the suspicious car driving around and around the same parts of the neighborhood. Good thing the Leaf is so quiet!) The charging took 4:40 hours and consumed 17.16 kWh according to the Blink's cumulative Energy values (kWh's after - kWh's before). I then immediately turned off the 80% Leaf timer, and the 80% to 100% charging began. That charging took 1:25 hours and consumed 4.69 kWh, so this implies the 0% to 100% charging took 6:05 hours and consumed 21.85 kWh. The temperature was near constant at 72-74 degrees and the charge took place outdoors (it was rainy as well). I have had my Leaf just over 2 months and 877 miles is now on the odometer. It has been driven conservatively in eco mode for most of those miles. Except for when the car was delivered, I have always charged to 80% up until this charge. My long term average mi/kWh has recently been 5.0 to 5.1, and 19.67 kWh x 5.0 mi/kWh = ~98 mi, which if correct is nothing for me to complain about -- in fact I would be quite pleased with.


Anybody else? Assuming the Leaf's charger is 90% efficient (since 17.16 kWh / 4.66 h = 3.68 kW and 3.3 kW / 3.68 kW = ~ .90), 90% of 21.85 kWh = 19.67 kWh would seem to be an estimate of my battery pack's current usable capacity. Does anyone think I have a battery pack problem or are my results typical?

Thanks in advance for anyone else's results!

 

[Boomer23]

Boomer23: Thanks for your results!

I have some additional data to add. I also drove my LEAF down to the second ("very low") battery warning and three flashing dashes and then charged to 80% last night. Before charging, the prototype SOC meter showed 6% charge remaining. The charge from my AV EVSE to 80% took 18.2 kWh per my TED system. The charge took 4 hours and 54 minutes.

I think that DaveinOlyWash and evnow would have the most experience to be able to discuss your charging data. Your estimate of available pack capacity looks low to me, and very low compared to most other estimates that I've seen.

 

[DaveinOlyWA]

I don't think your charger is that efficient. Since u were not to thelast bubble in turtle mode will have to assume u replaced less than the full 21.5 kwh estimated to be available.

Most here seem to report about 85-86 % efficiency at 16the amps 81-82 % at 12the amps and 75 % at 120 volts

 

[MikeD]

Boomer23: Your 0 to 80% charge session time of 4:54 is not much different than my 4:40 time (~5% difference). I had intended to measure the voltage last night during the charging, but it is currently 2 x 119v = 238v. I theorize that one possible explanation for the 14 min charge time difference could be just a difference between average charging voltage. It is harder to explain the 18.2 - 17.16 = 1.04 kWh charging difference -- I would not expect the EVSE should make much difference. Of course I would welcome any additional battery pack capacity below the second warning, even though I never intend to need it. If you are correct that there may be an additional 6% of battery pack capacity beyond the 2nd warning point, I calculate Total Capacity = 19.67 kWh / .94 = 20.93 kWh (again assuming 90% charger efficiency). If I assume a charger efficiency of 85% I calculate Total Capacity = (.85 x 21.85) / .94 kWh = 19.76 kWh. It would be of interest to know what efficiency the charger manufacturer claims for its Leaf charger.

In any case the MAIN REASON for this thread was to try to establish a standard (new) battery pack charging benchmark that would be easy for owners (at least for Blink owners) to determine now via specific charging data, which could be useful for owners to determine substandard battery pack capacity now and in the future.

I encourage and welcome additional "0 to 80% wall kWh's" data! "0 to 100% wall kWh's" data is also welcome. Multiple data points will show if there appears to be a low degree of "data scatter", and if so allows calculation of a useful average.

I am not trying to discourage SOC meter development/possible sales -- I am trying to investigate a possibly simple low-cost battery pack charging benchmark.

 

[Boomer23]

By the way, one small datum to add. After I posted last on this thread, I checked the state of charge using the prototype SOC meter and it read 82% after charging to 80% and before driving.

 

[planet4ever]

Dang! That must mean the SOC meter is reading the wrong data. I mean, after all, we can't have it agreeing with CarWings, can we? :lol: I've wasted a lot of ink explaining that the CarWings numbers are stupid lies, based on nothing more than counting bars.

Ray

 

[DaveinOlyWA]

ok here is my story; drove yesterday until i hit the _ _ _. was going to turtle but got tired of driving around. i live on a street that is one block long situated between two lakes so cruising the neighborhood is not as easy as one might think

ok, anyway drove 81.6 miles Car states 4.3 miles/kwh or about 19 kwh used.

plugged in and used just under 23 kwh to recharge on Modded EVSE which works out to be about 82.6% we will say 83% for reference.