Post Your Battery Degradation Results

[cjs998]

Yesterday, 4/11/2016, my 2012 Leaf lost its 9th bar with these stats:

56,311 miles / AHr 42.55 / SOH 64.23% / Hx 43.69%

Lots of range anxiety for past 3 months trying to complete my daily 50 mile round trip commute.

Chris,

 

[WetEV]

2014 SL

Ahr = 60.32 SOH = 92% HX = 92.9%

21048 miles 14 QCs 1170 L1/l2

Bought in February, 2014.

 

[DaveEV]

Just over one month to go before 5 years of ownership:

50k miles
194 GIDS 100% 160 GIDS 80%
45.3 Ah
48.2 Hx

What is interesting is that the rate of capacity loss appears to be going up, not down as one might expect.

2014: 3.13 Ah/year 0.26 Ah/month
2015: 4.75 Ah/year 0.40 Ah/month
2016: 5.48 Ah/year 0.47 Ah/month

Now, my commuting habits did change (higher average speed) and I work in a hotter area further inland, but that still doesn't explain the partial year 2016 capacity loss rate. Unfortunately 2013 data is affected by the P3227 update so isn't usable.

Still looks like I'm about 3-4 months from losing the 4th bar, just out of warranty. Bummer.

Regenerative braking continues to get worse as well. Most of the time it's negligible to 10-15 kW. Really noticable at 55 mph+ where SOC has to be very low to get any substantial regenerative braking. Regen at highway+ speeds now is now all the time like what it used to be near 100% SOC the first couple years.

 

[analyser]

- Ah
- SOC
- SOH
- Hx

Can anyone define these Leaf Spy metrics? How are those related:
- to design capacity (of XX AH),
- to each other,
- to other [energy, kWh] metrics reported by Leaf Spy
- to the 2 levels of charge - 80% and 100% and
- to the lowest allowable threshold (minimum left in the tank - when you are no longer be able to drive)?

Is there any capacity number used as a reference (e.g. 60AH)?

Full Charged Capacity (AH) could be below or above Desing Capacity. That has been captured by Idaho Lab tests in 4 brand new Leafs.

I've got used to terminology utilised by Texas Instruments for "gas gauges" utilised in majority of Li batteries in Laptops and tablets (almost any Laptop make and model nowadays):

- Design Capacity (e.g. 4.4 Ah)
- FCC - Full Charged Capacity. That is discharge capacity of the battery (Ah), i.e., the size of the “tank”
- RM - Remaining Capacity of the battery (Ah), i.e., the amount of “fuel” that is left in the “tank” RM = RSOC*FCC
- RSOC - Remaining State Of Charge (%). Percent full. RSOC = Remaining Capacity/FCC
- ASOC - Absolute State Of Charge (Ah). ASOC = Remaining Capacity/Design Capacity

2014 Leaf Service Manual suggests that VCM captures couple of capacity related metrics reported by LBC (aka BMS) but those are not defined in SM either.

 

[RegGuheert]

2014: 3.13 Ah/year 0.26 Ah/month
2015: 4.75 Ah/year 0.40 Ah/month
2016: 5.48 Ah/year 0.47 Ah/month

Over the past 12 months (May 1, 2015 to May 1, 2016) capacity dropped from 53.79 Ah to 51.76 Ah in just under 8,000 miles of driving, so it is right at 2 Ah/year.

 

[DaveEV]

Over the past 12 months (May 1, 2015 to May 1, 2016) capacity dropped from 53.79 Ah to 51.76 Ah in just under 8,000 miles of driving, so it is right at 2 Ah/year.

Less than half of mine. Stoaty's LEAF Battery Capacity Loss spreadsheet continues to track real-life numbers very well, his predicts about 2 Ah/year for your area and about 4 Ah/year for my area.

 

[RegGuheert]

Over the past 12 months (May 1, 2015 to May 1, 2016) capacity dropped from 53.79 Ah to 51.76 Ah in just under 8,000 miles of driving, so it is right at 2 Ah/year.

Less than half of mine. Stoaty's LEAF Battery Capacity Loss spreadsheet continues to track real-life numbers very well, his predicts about 2 Ah/year for your area and about 4 Ah/year for my area.

Actually, the degradation in my LEAF is 25% higher than what is predicted by Stoaty's calculator (22% actual versus 17.5% predicted). This is exactly as I have predicted:

Stoaty assumed that calendar losses would slow as the battery degraded and that cycling losses would proceed in a linear fashion. I have long stated that I think it should be the other way around: calendar losses should proceed linearly and cycling losses should slow as the vehicle ages.

The result of all this is that for vehicles like yours and mine where calendar losses are dominant, I predict the model will underpredict total losses by a larger and larger fraction as time goes on.

Note that at the time I made that prediction, Stoaty's calculator was closely matching the degradation for my LEAF.

BTW, I fixed some errors that had accumulated on the "Input" tab of the online spreadsheet over the last couple of years. It should work properly now. If anyone spots any problems, please let me know.

 

[brycenesbitt]

2011 SL
27028 miles Ten Bars Shown
Leaf Spy Data: 26 Quick Charges, 1362 L1/L2 charges
SOH 74% AHr=49.08 Hx=68.78%
Climate: Coastal California (rarely over 80 F outside). Car not garaged.

GOM is wildly inaccurate, leading to much range anxiety.

 

[TimLee]

... GOM is wildly inaccurate, leading to much range anxiety.

Use LEAF Spy Pro :!:

 

[dhanson865]

- Ah
- SOC
- SOH
- Hx

Can anyone define these Leaf Spy metrics? How are those related:
- to design capacity (of XX AH),
- to each other,
- to other [energy, kWh] metrics reported by Leaf Spy
- to the 2 levels of charge - 80% and 100% and
- to the lowest allowable threshold (minimum left in the tank - when you are no longer be able to drive)?

Is there any capacity number used as a reference (e.g. 60AH)?

Full Charged Capacity (AH) could be below or above Design Capacity. That has been captured by Idaho Lab tests in 4 brand new Leafs.

I've got used to terminology utilized by Texas Instruments for "gas gauges" utilized in majority of Li batteries in Laptops and tablets (almost any Laptop make and model nowadays):

- Design Capacity (e.g. 4.4 Ah)
- FCC - Full Charged Capacity. That is discharge capacity of the battery (Ah), i.e., the size of the “tank”
- RM - Remaining Capacity of the battery (Ah), i.e., the amount of “fuel” that is left in the “tank” RM = RSOC*FCC
- RSOC - Remaining State Of Charge (%). Percent full. RSOC = Remaining Capacity/FCC
- ASOC - Absolute State Of Charge (Ah). ASOC = Remaining Capacity/Design Capacity

2014 Leaf Service Manual suggests that VCM captures couple of capacity related metrics reported by LBC (aka BMS) but those are not defined in SM either.

A new 24 kWh battery is ~66 Ahr. I think some have reported 66.25.

SOC% in leafspy is the SOC as reported on the can bus. No modification, no curve, no offset, just raw SOC%.

SOC% on the dash (2013 or newer) has a curve at the bottom and top of the scale and differs from can bus SOC% in that way.

The difference between the two is mostly academic as charging to full jumps from low 90s % to 100% on either scale and you can't drive to 0% on either scale.

80% SOC% is true can bus 80%, 100% SOC is whenever the BMS decides to interrupt charging no matter if that is just after 50% SOC or just after 95% SOC. In reality it tends to be somewhere around 91-95% can bus SOC% right before charging stops but if there were severe degradation, a bad cell, or temperature issue charging to 100% could stop way before normal.

Hx is undefined / undocumented. It seems to be a health metric with some sort of hysteresis. I is assumed to be used in the bar drop logic but we don't know for sure what metric or metrics are used to determine bar loss.

SOH% is a health metric with 100% = new battery and little or no hysteresis.

AHr, SOH% and Hx all degrade at slightly different rates and I'd assume that they are related but it's unknown / undocumented so we can't say exactly how.

Lowest metric for being able to drive is known in GIDS and kWh. I find it easier to think in kWh. The limit there is around 0.5 kWh remaining. In a perfectly balanced pack with perfect temps you might drive to 0.4 kWh remaining but with a typical pack on a typical day you'll stop at 0.5 kWh left.

By GIDS I can quote Tony Williams

because it's triggered by the lowest cell pair voltage. This can happen with a Gid range from 4 to 8

and by "it" and "this" he means when the car is undrivable, stopped, dead.

 

[TimLee]

...
Hx is undefined / undocumented. It seems to be a health metric with some sort of hysteresis. I is assumed to be used in the bar drop logic but we don't know for sure what metric or metrics are used to determine bar loss.
...

More discussion of Hx:

http://www.mynissanleaf.com/viewtopic.php?f=44&t=20924&p=461013&hilit=conductance#p461013

 

[brycenesbitt]

... GOM is wildly inaccurate, leading to much range anxiety.

Use LEAF Spy Pro :!:

I have LEAF Spy Pro: it is more murky, and just about as poor a predictor, as the GOM. Range anxiety remains high.

 

[cwerdna]

... GOM is wildly inaccurate, leading to much range anxiety.

Use LEAF Spy Pro :!:

I have LEAF Spy Pro: it is more murky, and just about as poor a predictor, as the GOM. Range anxiety remains high.

Why do you say that? IIRC, you have an '11 so you don't have the % SoC dash display. Would you rather depend on the GOM and not granular enough 12 fuel bars? At least you can go by gids and screen 4 (http://www.electricvehiclewiki.com/Leaf_Spy_Pro#Screen_4). LBW sounds at 49 gids and VLBW sound at 24.

For screen 4, if you know you need to go 40 miles more, then tap it until you get the the threshold you want (LBW, VLBW or 5%). Then use the +/- buttons to arrive an efficiency value in miles/kWh (say 4.0) that you'll need to achieve to make it 40 miles. Then, reset the car's miles/kWh meter and make sure you drive so that you achieve 4.0 miles/kWh or greater. Can the stupid GOM help w/that?

And, at least w/Leaf Spy, you have visibility once you hit LBW and VLBW. I believe turtle is triggered by what's mentioned at http://www.mynissanleaf.com/viewtopic.php?p=379287#p379287, which you also have no visibility unless you have something like Leaf Spy.

 

[lorenfb]

Use LEAF Spy Pro :!:

I have LEAF Spy Pro: it is more murky, and just about as poor a predictor, as the GOM. Range anxiety remains high.

Why do you say that? IIRC, you have an '11 so you don't have the % SoC dash display. Would you rather depend on the GOM and not granular enough 12 fuel bars? At least you can go by gids and screen 4 (http://www.electricvehiclewiki.com/Leaf_Spy_Pro#Screen_4). LBW sounds at 49 gids and VLBW sound at 24.

For screen 4, if you know you need to go 40 miles more, then tap it until you get the the threshold you want (LBW, VLBW or 5%). Then use the +/- buttons to arrive an efficiency value in miles/kWh (say 4.0) that you'll need to achieve to make it 40 miles. Then, reset the car's miles/kWh meter and make sure you drive so that you achieve 4.0 miles/kWh or greater. Can the stupid GOM help w/that?

And, at least w/Leaf Spy, you have visibility once you hit LBW and VLBW. I believe turtle is triggered by what's mentioned at http://www.mynissanleaf.com/viewtopic.php?p=379287#p379287, which you also have no visibility unless you have something like Leaf Spy.

Or just use the Ahr from LeafSpy, it's your simplest form of a true "gas gauge". It's not like SOC which is not
useful for a reliable range estimate. Once you have "calibrated" your typical miles per Ahr under various
driving conditions, you'll have a good estimate of your remaining range without the unreliable estimates
from the GOM, SOC, or bars remaining. Besides, you're not having to use data from multiple screens for
a simple calculation easily done in your head. Just think how it would be driving an ICEV without a gas
gauge and having total reliance on your trip computer for your only indication of remaining range.

I assume my "turtle" to be about 15 Ahr (my "tank empty") and calculate usable range based on that.

 

[brycenesbitt]

I think the issue here is I don't commute in the car: each trip is different so there's not a "typical" kwh/miles value I can enter in for a given trip...
combined with the deteriorating 2011 battery I'm scared to go anywhere more than 30 miles one way (assuming a charger at the destination).

 

[vrwl]

Why do you say that? IIRC, you have an '11 so you don't have the % SoC dash display. Would you rather depend on the GOM and not granular enough 12 fuel bars? At least you can go by gids and screen 4 (http://www.electricvehiclewiki.com/Leaf_Spy_Pro#Screen_4). LBW sounds at 49 gids and VLBW sound at 24.

For screen 4, if you know you need to go 40 miles more, then tap it until you get the the threshold you want (LBW, VLBW or 5%). Then use the +/- buttons to arrive an efficiency value in miles/kWh (say 4.0) that you'll need to achieve to make it 40 miles. Then, reset the car's miles/kWh meter and make sure you drive so that you achieve 4.0 miles/kWh or greater. Can the stupid GOM help w/that?

And, at least w/Leaf Spy, you have visibility once you hit LBW and VLBW. I believe turtle is triggered by what's mentioned at http://www.mynissanleaf.com/viewtopic.php?p=379287#p379287, which you also have no visibility unless you have something like Leaf Spy.

This is truly the BEST part about Leaf Spy Pro. A year ago, I had to make a trip that I normally wouldn't even consider in my LEAF. I live at the top of a mini-mountain, and so the trip down used very little energy. But I knew the trip back up would stress the limits of my degraded battery. So I did the exact same thing cwerdna suggested. I knew the milage I had to go. I reversed the predictive process of the Leaf Spy Pro and used my plus and minus signs to figure out what my minimum efficiency HAD to be in order to go the 35 miles I needed to go. The magic number was 3.2kWh. I reset my dashboard efficiency settings and started off.

As I continued to drive, I had to go slower and slower up the big hill in order to keep my efficiency at the minimum requirement of 3.2kWh. But that's ok. As long as I was able to keep it at 3.2 or greater, I knew I'd make it home. Luckily it was at night, on a less frequently traveled road, so I only had to pull over once to let a car behind me pass. I was incredibly nervous, but the Leaf Spy Pro was correct. I made it home with about 2 miles to spare on my car's GOM. Best thing I ever did was get that app for my phone.

 

[phxsmiley]

My 2011 Leaf just dropped it's 4th BAR this past week, with LeafSpy reporting the following:

GIDs: 184
SOC: 94.6
KWh: 14.3
AH: 40.99
Miles: 73,401

What's unique here is that I might be the first one posting 4BL on their 'second' battery. My battery was replaced in 2013, before the 2015 batteries were available.

The car still functions well, except for the capacity loss of course.

 

[GerryAZ]

My 2011 Leaf just dropped it's 4th BAR this past week, with LeafSpy reporting the following:

GIDs: 184
SOC: 94.6
KWh: 14.3
AH: 40.99
Miles: 73,401

What's unique here is that I might be the first one posting 4BL on their 'second' battery. My battery was replaced in 2013, before the 2015 batteries were available.

The car still functions well, except for the capacity loss of course.

I would be there also if the 2011 had not met its demise since its replacement battery (installed 10/4/2013) was already down to 11 bars. The "lizard" battery is doing much better in the 2015.

Have you talked to Nissan about getting a 2015 battery? There was some discussion from one of the Nissan managers that those getting early battery replacements could get updated batteries after they became available, but I did not receive any information regarding that.
Gerry

 

[phxsmiley]

I have had some discussions with a couple of Nissan contacts, but no final word yet. I had contacted them earlier in the year, and they encouraged me to check back with them when the weather warms up and range decline accelerates again.

Unfortunately, I had a recent job change and would like to keep the car longer, but it is running near the end of it's usable life for me. I usually keep my cars much longer than this.

 

[DaveEV]

Unfortunately, I had a recent job change and would like to keep the car longer, but it is running near the end of it's usable life for me. I usually keep my cars much longer than this.

It's running near it's usable life because of lack of range?

It's crazy that you've gone through two packs in less than 5 years and 73k miles. That Arizona heat!

IMO this is a case where you should have received a lizard pack given what was stated publicly and given that the settlement stated that you should have received a battery with the latest, aka lizard, tech.