2013 Low Battery Capacity AHr Battery Degradation

[TonyWilliams]

If memory serves, Tony asked for a battery temperature capacity coefficient. Jim has done an awesome job, and perhaps he will find some time to implement this in the future. In the meantime, I wouldn't trust the app blindly. It's amazing and provides so much information, but not all of it has to be 100% correct.

Here's a repost on this subject from the "other" thread:

Max charge on a new battery is reported to be 281 GIDs which would be 22.48 kWh.

1) Is the app showing a DTE (when 4 miles per kWh is selected) of 4 * 22.48 = 89.9 miles with no reserve?

2) Would it be possible to add temperature corrections, since you have the temperature data?

1) DTE is based on the current selection and remainng GIDs. For LBW that would be (remaining GIDs-49)*0.08*(miles/kWh). For VLBW change the 49 to 24. For DTE to "rsrv" it would be ((remaining GIDS*0.08)-Reserved energy in kWh)*(miles/kWh). There is no way to show DTE with no reserve since the lowest reserve is 0.2 kWh.

Ok, that's what I thought you were doing. For the record, I have never driven any LEAF of the dozens that I have tested to Turtle (and even my own car about two dozen times to Turtle) that met the 0.08kWh per GID times miles/kWh = range autonomy in miles. I don't know of anybody short of Nissan that has done this as many times as I have in so many controlled drives. Yes, I know what the Nissan book says a GID equals.

No sane driver is going to get to 0.2kWh remaining, so could we make the minimum reserve higher... maybe 0.48kWh? (6 Gids). It really is time to get off the road and the car will very likely be in Turtle, or very, very close to Turtle. Yes, I know what cell pair voltages are.

2) Just change your miles/kWh to adjust for temperature. There are no plans to make any auto adjustments based on temperature.

How would a technically disinterested person know to do that, or how much to "adjust" for? Heck, I wouldn't know how much to adjust for without some good number crunching, and I'd say that I'm pretty adept at this stuff. How much would you adjust the miles/kWh with a car cold soaked at -10F versus one at 70F?

Even more confusing would be that any adjustment would vary significantly from the readout on the dash. For the record, I do appreciate that you included a reference to DTE in the way I suggested it earlier. I'd just like it to be the best that it can be.

 

[surfingslovak]

I'd just like it to be the best that it can be.

Yes, well stated and a great post!

 

[Boomer23]

If you get close to 86 miles of range at an average of 4.0 mi/kWh or 98 miles of range at 4.5 mi/kWh, you shouldn't be concerned. Assuming we can believe the dash energy economy meter (a big IF, I agree), you'll be close to 21.5 usable kWh, which we believe is what the LEAF pack holds.

Which is exactly why we do range tests at a fixed speed, hence fixed power consumption on level, no wind dry hard surface roadways, tires at 36 psi (on the Ecopias... the new Michelins might be a little off).

Then, we can see the errors more clearly. If you car was doing funny business with the low end Gids, I would not trust it to be very accurate with the economy.

If the car can drive at 100km/hr ground speed (whatever that is on your speedometer, typically 65mph) for a distance of 84 miles, then you have 21kWh useable. On the flat terrain described above, it should be 4.0 miles/kWh. But, even if the economy showed some crazy number, the fact remains that the power consumed will be a constant.

Oh, and the battery needs to be close to 70F. If it's hotter, obviously it has a wee bit more oomph.

Tony's correct, of course. That constant speed and temperature will control for a lot of factors.

The energy required for recharge does, for my own purposes, add some credence to my range measurement, and gives me reason not to be concerned about my pack's health.

Something odd is going on with these 2013 packs, though. There seems to be something odd going on in the relationship between Gids at 80% charge and at 100% charge. I'm getting only 75.4% Gids at an 80% charge, but 97.8% Gids at 100%. In the older LEAFs, the 80% charge was always close to 80% when the car was new, but the 100% charge was lower than 100%. In this new car, that relationship seems to be reversed. It almost seems like there is more energy between an 80% charge and a 100% charge in the new cars than there was in the old cars. Just an idea, but that's the feeling I'm getting.

 

[surfingslovak]

Something odd is going on with these 2013 packs, though. There seems to be something odd going on in the relationship between Gids at 80% charge and at 100% charge.

Indeed, and I'm wondering if we will get to the bottom of this. Although, and thankfully, it does not appear to be as dramatic as the the capacity bar loss reports from Phoenix, which Drea kicked off last year. I remember that Jay purchased a 2011 LEAF with 265 GIDs on a full charge in Dallas and Matt bought a vehicle in a similar condition in Fresno last summer. Both baked on dealer parking lots for several months, which seemed like an acceptable explanation. The 2013 data coming in so far looks like a mystery to me.

 

[stjohnh]

Something odd is going on with these 2013 packs, though. There seems to be something odd going on in the relationship between Gids at 80% charge and at 100% charge.

GOOD NEWS !! My battery is fine, and probably those of the other people with 60-62 AHr capacity 2013 Leafs.

I ran my car to turtle (first time ever) AND Ta Da!! 28 miles from LBW to turtle, much more than predicted, which gives me total range from 100% to turtle of 90 miles at 4.0 mi/kwh.

Other VERY curious observations: as I got down around 10 gids, the energy effic meter suddenly jumped from 4.0 mi/kwh to 4.7 mi/kwh, without any change in my driving. Also, as I got below 10 gids I noticed that the miles/gid seemed a lot more than it should be. By the time I started measuring, I got 4 miles on one gid, going from 7->6 gids. Got turtle at 5 gids. The Leaf Battery app (v026) predicted 15 miles to from LBW to .6kwh (expected turtle) but I got 28 miles. I think Nissan has changed something in the programming. And I can go a lot farther per gid when gids are below 10 on my 2013 Leaf.

Also, as expected LBW came at 49gids, 18% SOC on the Leaf Dash.

Anyway, what's going on with the all this is unclear, hopefully someone can help explain.

 

[Staque]

Battery app version 0.26h

2013 SV with 4,000 miles
67.36AH, health 111.22%
282 GIDs full charge this morning, ambient 70 degrees.

 

[mkjayakumar]

Jay purchased a 2011 LEAF with 265 GIDs

FWIW: After 20K miles and into the 2nd summer now, I have 225 Gids.. tomorrow I am sure 224

 

[dm33]

Battery app version 0.26h

2013 SV with 4,000 miles
67.36AH, health 111.22%
282 GIDs full charge this morning, ambient 70 degrees.

Just curious, what range did the GOM predict?

 

[Boomer23]

GOOD NEWS !! My battery is fine, and probably those of the other people with 60-62 AHr capacity 2013 Leafs.

I ran my car to turtle (first time ever) AND Ta Da!! 28 miles from LBW to turtle, much more than predicted, which gives me total range from 100% to turtle of 90 miles at 4.0 mi/kwh.

Other VERY curious observations: as I got down around 10 gids, the energy effic meter suddenly jumped from 4.0 mi/kwh to 4.7 mi/kwh, without any change in my driving. Also, as I got below 10 gids I noticed that the miles/gid seemed a lot more than it should be. By the time I started measuring, I got 4 miles on one gid, going from 7->6 gids. Got turtle at 5 gids. The Leaf Battery app (v026) predicted 15 miles to from LBW to .6kwh (expected turtle) but I got 28 miles. I think Nissan has changed something in the programming. And I can go a lot farther per gid when gids are below 10 on my 2013 Leaf.

Also, as expected LBW came at 49gids, 18% SOC on the Leaf Dash.

Anyway, what's going on with the all this is unclear, hopefully someone can help explain.

That's good news and reassuring for you, now that you have done a full range test. I do encourage everyone with a new EV to do such a test, just to get a feel for how their car will behave as it nears very low charge, and to get a feel for range under driving conditions that they know personally. It's also reassuring for me to hear that your car performed similarly to mine at very low Gids.

Now let's take a step back and think of what Nissan has presented to the average driver, or even yourself prior to your recent range test, especially someone without a GIDmeter or ELM/Android app. The driver is faced with LBW at 2 bars of charge and a falsely low GOM estimate. Then VLBW occurs and GOM goes to ---. What is the driver to assume? That he should stop immediately and find a charge point. But he would be sacrificing perhaps 10 or 15 miles of available range.

Over the years, Nissan has released several software updates that have gone back and forth between being cautious and extra cautious about warning drivers when charge is seriously low. The behavior that you and I are seeing with these May 2013 cars seems to be overly conservative, and hiding 7 or 8 miles of reserve below the 10 Gid mark.

If we are going to take advantage of our cars' useful range, it seems to be more essential than ever to have some kind of GIDmeter or app, because much more useful range is "hidden" below 10 Gids. When taking longer trips, we maybe should also get used to feeling comfortable running our cars down to 10 Gids when we're trying to stretch range. It's a strange new world!

 

[stjohnh]

If we are going to take advantage of our cars' useful range, it seems to be more essential than ever to have some kind of GIDmeter or app, because much more useful range is "hidden" below 10 Gids. When taking longer trips, we maybe should also get used to feeling comfortable running our cars down to 10 Gids when we're trying to stretch range. It's a strange new world!

True, but I was getting used to the idea that the Leaf Battery App and my WattsLeft meter were accurate. Unfortunately, while accurate at predicting 100% to LBW mileage, I am now left with mental "adjustments" to get true range. I'm sure Jim will figure out how to correct that, but it will likely take further understanding of why there is more energy in the gids < 10 than other gids.

I didn't check to see if the app was accurate at predicting 100% to VLBW distance.

 

[dm33]

That's good news and reassuring for you, now that you have done a full range test. I do encourage everyone with a new EV to do such a test, just to get a feel for how their car will behave as it nears very low charge, and to get a feel for range under driving conditions that they know personally. It's also reassuring for me to hear that your car performed similarly to mine at very low Gids.

Its hard for me to perform a reliable test as there is no level road around here. All rolling hills. So its hard for me to judge what sort of mileage I should get from a charge.
My car was made in March 2013 and is reporting capacity around 93%.

GOOD NEWS !! My battery is fine, and probably those of the other people with 60-62 AHr capacity 2013 Leafs.

Did values changes in the LEAF app? Did your capacity, Ahr, GIDs change at 100% after performing this test? My battery maxes out at 21.6kwh. Sounds like you used 22.5 out of your battery. What kwh capacity does it show now at 100%?

 

[stjohnh]

Did values changes in the LEAF app? Did your capacity, Ahr, GIDs change at 100% after performing this test? My battery maxes out at 21.6kwh. Sounds like you used 22.5 out of your battery. What kwh capacity does it show now at 100%?

Don't know, haven't charged to 100%, I'll post when I do.

 

[bradbissell]

My leaf battery capacity seems to have dropped since the east coast heat wave. The Ahr reading and health seem to jump around quite a bit so one reading is not the most accurate way to judge overall battery capacity, but you can get a general trend over time.

My %CAP is based on my delivered battery Ahr of 67.362

Built 3/13 Delivered 3/31/13

Date-------Ahr------%CAP----%SOC----Health----- GIDS----V Max---mv Delta---Max Batt Temp F---- Total Miles
6/24/13---66.850---99.240--97.100----------------------4.135----10.000-----80.000
7/22/13---67.050---99.537--96.900----103.090----283----4.125----9.000------79.500
8/1/13----65.880---97.800--96.900----100.910----283----4.132----13.000-----79.700------------4960

 

[TonyWilliams]

GIDS----V Max
283----4.132

Now, this is something we rarely saw in a 2011-2012 LEAF.

 

[surfingslovak]

GIDS----V Max
283----4.132

Now, this is something we rarely saw in a 2011-2012 LEAF.

Indeed. Jens reported 283 occasionally from Norway. The voltage looks way too high. Any idea what the real SOC was? EDIT: 97%. Isn't that a bit like range mode on a Tesla?

 

[bradbissell]

I have seen 284 as a max GID count. Voltage does seem high, as if they are pushing the cells just a bit harder to increase performance. Perhaps this is due to the elusive chemistry tweak we have heard about?

Also pretty sure my pack is from Japan. I wonder if the packs in cars produced in May (or have lower Ahr) are the ones from Smyrna?

 

[stjohnh]

I have seen 284 as a max GID count. Voltage does seem high, as if they are pushing the cells just a bit harder to increase performance. Perhaps this is due to the elusive chemistry tweak we have heard about?

Also pretty sure my pack is from Japan. I wonder if the packs in cars produced in May (or have lower Ahr) are the ones from Smyrna?

For my S at full charge: (from Leaf Batt App ver026 gen release)
Vmax=4.134 Gids=262 cap=60.37 AHr

For my wife's SV:
Vmax=4.133 Gids=264 cap=60.83

Both cars made in May.

 

[TonyWilliams]

I have seen 284 as a max GID count. Voltage does seem high, as if they are pushing the cells just a bit harder to increase performance. Perhaps this is due to the elusive chemistry tweak we have heard about?

I suspect it is to make up for slightly lower battery density, as the range tests that I did with two separate 2013's were not even close to a 2011 - 2012 LEAF in ultimate range at 65mph.

Plus, the motor may be slightly less efficient with 40% less REM's. All guessing, of course, but the end result isn't. A 2013 has slightly less range with probably the same or improved aerodynamics and the same or lighter weight. That translates to less battery density or lower efficiency somewhere. The torque was also reduced for 2013.

 

[Rauv]

None of the theories here yet can explain why some 2013s have higher AH capacities than other 2013s, right? Is there a code in the VIN that can be used to separate all 2013s into two camps to see if there is any correlation to manufacture date (battery, not car)?

 

[LEAFfan]

I have seen 284 as a max GID count. Voltage does seem high, as if they are pushing the cells just a bit harder to increase performance. Perhaps this is due to the elusive chemistry tweak we have heard about?

I suspect it is to make up for slightly lower battery density, as the range tests that I did with two separate 2013's were not even close to a 2011 - 2012 LEAF in ultimate range at 65mph.

Plus, the motor may be slightly less efficient with 40% less REM's. All guessing, of course, but the end result isn't. A 2013 has slightly less range with probably the same or improved aerodynamics and the same or lighter weight. That translates to less battery density or lower efficiency somewhere. The torque was also reduced for 2013.

If all that's true, then how did that one poster obtain over 90 miles to Turtle at 4.0mpkW with a 2013?