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Discuss data from the LEAF Battery app, and Comparisons

Posted: Mon May 13, 2013 9:01 am
by garygid
Please use this thread to discuss the meaning of data obtained
from the LEAF Battery app, and comparisons with data obtained
from other devices or sources (like direct measurements).

Re: The meaning of data obtained from the LEAF Battery app

Posted: Mon May 13, 2013 9:03 am
by garygid
We have data in these areas, some are less well understood:

Cell-pair
96 Voltages
96 Shunts (we assume, but not well understood yet)

Battery Pack
four Temperatures
SOC, high precision, but unknown accuracy
Amp-hours (possibly related to pack capacity)

Brake Force
Mechanical
from Regen

Calculated Vatues:
CAP
DTE
'GIDs

Others:

Re: The meaning of data obtained from the LEAF Battery app

Posted: Mon May 13, 2013 9:04 am
by garygid
misc 2

Re: Discuss data obtained from the LEAF Battery app

Posted: Thu May 16, 2013 4:21 am
by RuneW
jclemens wrote:I have 30,000km (18600mi) on a Nov 2011 Leaf and Cap is 97.3%
Is that good? I dunno. I was hoping for 98+
I have a CAP of only 92.93% and I think this is quite disappointing considering that:

- The car is only a year old
- I have driven it only 11.000 km
- I have fast charged only 2 times
- I'm charging to 80% most of the time (charging to 100% biweekly to balance the cells as advised)
- I have only gotten low battery warning 3 times in total
- I have never experienced "very low battery" or "turtle"
- I live in Norway with an ideal climate for batteries (or so they say)

Image

I feel that the SOC value is surprisingly low under these conditions! Is this value within the "norm"? or is there a chance that the app is calculating something wrong? The CAP values seem to be between 97 and 102 for all other vehicles (in Norway at least)...

Re: Discuss data obtained from the LEAF Battery app

Posted: Thu May 16, 2013 7:00 am
by garygid
For lower battery pack Temperatures, like the 10 degrees C that
you show, there is possibly some reduction in effective capacity,
just because of the lower temperature, or lower temperature
cycles in the car's recent history.

If so, then the nominal capacity might only appear after operating at
nominal temperatures, perhaps closer to something like 20 degrees C?

Please remember, CAP is not THE CAPACITY, but a guess based on
an estimate of an unfamiliar quantity.

Re: Discuss data obtained from the LEAF Battery app

Posted: Thu May 16, 2013 9:01 am
by edatoakrun
="RuneW"... is there a chance that the app is calculating something wrong? ...
Probably not the app, but our LEAFs, IMO.
garygid

...For lower battery pack Temperatures, like the 10 degrees C that
you show, there is possibly some reduction in effective capacity,
just because of the lower temperature, or lower temperature
cycles in the car's recent history.

If so, then the nominal capacity might only appear after operating at
nominal temperatures...
Or maybe not.

My capacity reports at app-reported temps from ~59 f to ~86 F are extremely consistent, varying only ~0.20 % since the first capacity report I got at the SF BayLEAFs meeting over a month ago. Most recently:

Image

That being said, I think they are consistently wrong, in showing an ~12.5% loss of capacity, which has not shown up in my LEAF by either recharge or range capacity tests.

What I have seen that has surprised me is that there is only a rough correspondence between the (erroneous, IMO) loss of capacity indicated by CarWings in total kWh use from "100%" to ~VLBW (as reported less accurately, in the nav screen m/kWh and dash m/kWh reports) and that reported by the app.

For example, the app showed kWh use of 16.8 for my last 108.7 mile capacity/range test on 5/11, while CarWings reported 16.4 kWh use for the same trip.

But after multiple tests I now believe this is because the app is picking up “gauge error”, quite likely temperature dependent, in real time as I drive.

While I was running errands yesterday, the app showed increasing kWh capacity, gid counts, and negative Wh use, corresponding to increases in battery temperature reports, and the (very unusual, in my experience) increase in charge bars from six to seven.

I took this screenshot shortly after I restarted both the app and my LEAF, which had dropped to six charge bars on the restart:

Image

Over the next ~1.5 miles, and ~ 1 hour, as I ran some errands and while I made three stop/restarts of my LEAF, I watched the charge reports by the app increase, (and at some point the seventh charge bar reappeared !) until reaching this point:

Image

As I used WH as I drove, the negative Wh decreased, but whenever I was not driving, it continued to increase.

This was fascinating to watch, but I had to get home. As I drove further, the Wh use went positive, and
I lost the seventh charge bar for the second time after another ~6 miles just before I took this shot:

Image

I think these observations may explain a lot about the erratic behavior of the charge bars...

Re: Using clone ELM327 Bluetooth OBDII adapter with Leaf

Posted: Thu May 16, 2013 10:04 am
by sorphin
So I did my 100% charge.. then did my running.. Before and After pics below... Not sure what thread to put anything in at this point. So i'm putting it here. Note: I had to adjust my Ahr on the settings screen to 67.35 to get a CAP of 100.02%

Note: I also changed the 'reserve' to 8%, based on the post from yesterday.

Before: (Dash said 100% / Range 103mi)
Image

Image

Image

After: (Dash said 57% (iirc) / Range: 59mi)
Image

Image

Image

Re: Discuss data obtained from the LEAF Battery app

Posted: Sat May 18, 2013 8:18 pm
by JPWhite
I noticed I had lost quite a bit of battery capacity in short order. I found it was Thursday (May 16th) and did an analysis of what was going on to cause the 0.3 reduction in Ah in a single day.

As one might predict based on what happened (and is happening) in Arizona, high battery temp is the culprit.

Here's a graph of battery temp and Ah of the battery on Thursday this week. My battery got to 90F. :o

Left axis an orange line is battery temp
Right Axis and blue line is Ah of the battery.

Image

Battery Ah never recovered overnight after cooling.

Daily degradation appears to be .02 or .03 Ah. So once battery temp gets above 86 or so, the degradation accelerates by one order of magnitude !!

This is just one day, but it does look like single incidences can impact overall battery health.

Re: Discuss data obtained from the LEAF Battery app

Posted: Sat May 18, 2013 8:33 pm
by DaveEV
JPWhite wrote:I noticed I had lost quite a bit of battery capacity in short order. I found it was Thursday (May 16th) and did an analysis of what was going on to cause the 0.3 reduction in Ah in a single day.
I'm 99% sure that the Ah reading is temperature compensated in some way as we know that GIDs are - reading lower in hotter temperatures and higher in colder temperatures.

In fact, cliff found that the formula GIDs = SOC * .31 - 15 - in a couple of spot checks I have found the formula to match up on my car, too.

Re: Discuss data obtained from the LEAF Battery app

Posted: Sat May 18, 2013 8:34 pm
by Stoaty
JPWhite wrote:I noticed I had lost quite a bit of battery capacity in short order. I found it was Thursday (May 16th) and did an analysis of what was going on to cause the 0.3 reduction in Ah in a single day.

As one might predict based on what happened (and is happening) in Arizona, high battery temp is the culprit.

Here's a graph of battery temp and Ah of the battery on Thursday this week. My battery got to 90F. :o

Battery Ah never recovered overnight after cooling.

Daily degradation appears to be .02 or .03 Ah. So once battery temp gets above 86 or so, the degradation accelerates by one order of magnitude !!
I would want longer follow-up when the battery had cooled to 5 bars to be certain the loss is permanent. However, doesn't look too good. How did you get your battery to 90 degrees? QC? Parking on hot blacktop? What was the ambient temp?