How degraded is my battery ?

[madbrain]

I did the following round trips thursday after my car (MY2012 SL) was fully charged on L2 at work and had all 12 bars.
This is the data from carwings :

1) First leg
Total consumption : 9.7 kWh
Consumption : 10.4 kWh
Regeneration : 0.8 kWh
Distance traveled : 33.7 miles
Energy economy : 3.5 miles/kWh

This was driven at 65 mph with cruise control and A/C on.
Mostly freeway, maybe about 4 miles city driving.
No major hills were involved, but the freeway is not completely flat.

This correlates fairly well with Tony's chart which states 3.6 miles/kW for 65 mph speed.
The trip used 7 of the 12 battery bars.

2) return leg
Total consumption : 7.0 kWh
Consumption : 7.9 kWh
Regeneration : 0.9 kWh
Distance traveled : 33.6 miles
Energy economy : 4.8 miles/kWh

Given that I only had 5 bars left to make the return trip, I had to slow down. I was driving mostly 50 miles/hour on cruise control except that I hit some roadwork for about 3 miles during which there was stop and go traffic.
Even so, the end of the trip was still pretty scary. I drove about 5 miles past the Very low battery warning (---), including 3 on the freeway still at 50. I still did not hit turtle. But there couldn't have been too much energy left in the battery.

Tony's chart states that 50 mph driving is 4.6 miles/kWh, and again that is pretty close to the 4.8 miles/kWh I got - the difference is explained by the roadwork.

So, the miles/kWh relating to speed seem to be accurate on the chart.
My issue is with the range on the chart.

The range chart states that at 65 mph or 3.6 miles/kWh, I should get about 75 miles with 12 bars or 71 miles with 11 bars (assuming my 12th bar is just about to go). Either way, it should have been no problem to drive the return trip at 65 mph according to the chart. If I believed the instrumentation on the car, there is no way this would have been possible, given the fact that I already drove 5 miles past VLBW and felt quite lucky to have made it back to a charger.

I also note that the net consumption of the two trips is only 9.7 + 7.0 = 16.7 kWh - only 79% of the 21 kWh of usable capacity that a new Leaf is supposed to have. Even if my first battery bar is about to go, does that first bar really represent close to 4.3 kWh ?

The average consumption for both trips was (33.7 + 33.6) / (9.7 + 7.0) = 4.02 miles/kWh.
According to Tony's chart a Leaf driving 3.9 miles/kWh and 12 battery bars should have a range between 78 and 82 miles.
But I drove 67.3 miles including 5 past VLB.

On Tony's chart, at 3.9 miles/kWh a range of 67.3 miles corresponds to 10 battery bars - between 66 and 72.

So what is going on here ?

1) is the Carwings data wrong ?
I am not inclined to think so, given that the miles/kWh from Carwings are matching the miles/kWh from Tony's range for the speed I drove.

2) is the range of Tony's chart wrong ?

3) did Nissan's recent software update significantly change the capacity reflected in each battery bars vs when Tony' did his tests ? I know they claim that they didn't, but this seems suspicious.

My car is not 1 year old yet, and has only 9000 miles. I definitely think there is some capacity degradation since the time I first got it, despite all 12 bars still being there. This summer, I took a 3 weeks trip to Europe. I make sure to leave the car unplugged and with only 6 bars of battery charge. But a friend of mine who was doing house & pet sitting thought I "forgot" to plug in the car, and plugged it in the next day after I left. I told him to unplug the car t after I received the end of charge text. But the car ended up sitting with about 100% state of charge for 3 weeks in my hot garage in August. So, I'm sure the car now has some battery degradation as a result, and I wouldn't be surprised if the 1st bar is about to go. But still, the range I am observing doesn't even match a car with 11 bars on Tony's chart.

 

[Stanton]

The best way to check the capacity of your Leaf is by plugging it into one of the ODB/CAN bus meters to see the Ahr rating. However, there will be some residual settling from the recent software update that may affect that reading for several weeks (you didn't say exactly when you had the update).

Having said that, your friend definitely didn't do you (or your Leaf) any favors by plugging it in after you left: 3 weeks is a LONG time to sit @100%, ESPECIALLY in the heat.

 

[madbrain]

The best way to check the capacity of your Leaf is by plugging it into one of the ODB/CAN bus meters to see the Ahr rating. However, there will be some residual settling from the recent software update that may affect that reading for several weeks (you didn't say exactly when you had the update).

The update was done on July 3. I went on vacation on July 26.

Having said that, your friend definitely didn't do you (or your Leaf) any favors by plugging it in after you left: 3 weeks is a LONG time to sit @100%, ESPECIALLY in the heat.

Yes I know It wasn't at 100% anymore after the 3 weeks though; more like 88%.

 

[TonyWilliams]

...
Even so, the end of the trip was still pretty scary. I drove about 5 miles past the Very low battery warning (---), including 3 on the freeway still at 50. I still did not hit turtle. But there couldn't have been too much energy left in the battery...

The average consumption for both trips was (33.7 + 33.6) / (9.7 + 7.0) = 4.02 miles/kWh.
According to Tony's chart a Leaf driving 3.9 miles/kWh and 12 battery bars should have a range between 78 and 82 miles.
But I drove 67.3 miles including 5 past VLB.

Since your driving is largely consistent with your average economy, my guess is the only other logical issue... battery degradation.

It would be very easy for me to believe you had 10-15% degradation, particularly after the vacation ordeal.

The Range Chart comes in a 93% capacity and 85% capacity, amongst others.

You came very close to Turtle, so lets just say you had 70 miles of performance at 4 miles/kWh

85% of 21kWh = 17.85kWh

70 miles / 4 miles per kWh = 17.5kWh

See any patterns? You need to get a Gidmeter or the new LEAF Spy app to help verify the degradation.

 

[madbrain]

Tony,

...
Since your driving is largely consistent with your average economy, my guess is the only other logical issue... battery degradation.

It would be very easy for me to believe you had 10-15% degradation, particularly after the vacation ordeal.

The Range Chart comes in a 93% capacity and 85% capacity, amongst others.

You came very close to Turtle, so lets just say you had 70 miles of performance at 4 miles/kWh

85% of 21kWh = 17.85kWh

70 miles / 4 miles per kWh = 17.5kWh

See any patterns? You need to get a Gidmeter or the new LEAF Spy app to help verify the degradation.

Yes, I do think it's degradation. I plan on getting the OBD2 dongle to use the Leaf spy app.
(If anyone on the forum has a spare one and is local to San Jose, please PM me).

However, let me point out that your own chart states that a car with 85% of the full battery capacity should be one with 11 battery bars. According to your chart, 11 bars corresponds to 84% to 91.5% .
But my car still has all 12 bars, so in theory it should have between 91.5% and 100% according to the same chart. These numbers are from your chart at http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295" onclick="window.open(this.href);return false; , which was last updated by you on Sep 4.
I don't see the numbers 93% and 85% on that chart.

Also, the actual consumption from Carwings was 16.7 kWh which is 79.5% of 21 kWh, not 85%.
As you said yourself, I was likely pretty close to hitting turtle. Your chart says there is only 1.4% of the 21 kWh capacity left once you hit turtle, which corresponds to 0.294 kWh .

This would put my battery capacity closer to 17 kWh than 17.85 kWh. Ie. somewhere around 17/21 = 80.95% of the battery, which corresponds to the mid-way point of a car with 10 battery bars in your chart. Yet again, my car still has all 12 bars...

I am thinking that there is something fishy about the Nissan software update. I don't think it's a coincidence that they did this around the time they announced the battery warranty for "9 battery bars". It seems to me that Nissan can do whatever it wants in the firmware to change what 9 battery bars actually means over time. They could show all 12 bars on every car if they wanted to. So, I wonder what this battery warranty really is worth.

9 bars on your range chart means a state of charge of 70.8 to 77.9%. If my car is really already at 81% max, you would think it would pretty close to losing the 10th bar... Yet it's still showing all 12.

 

[madbrain]

Sorry, I just noticed you had another chart for "1 year old+ battery, all 12 bars still showing", where I do see the numbers 93.0% and 85.1%.

I don't understand why the battery bars charge boundaries should change over the life of the car.
Your "new car" chart claims 12 bars corresponds to 91.5% to 100% charge.
Yet on a "1 year old" car, 12 bars corresponds to "85.1% to 93.0%".
This is roughly the same range as a new car with 11 bars, which is "84.0% to 91.5%".
Why does the battery bar boundary change over time ? How can anyone rely on the bars if their meaning changes that much ?

But even that "1 year old car" chart shows a minimum of 85.1% battery for a car with 12 bars, which is 17.85 kWh as you said. But I think my car is already under 17.85, based on the 16.7 kWh consumed with 5 miles past VLB.

 

[RegGuheert]

Most reports here indicate the fist bar does not disappear until about 81% of 21 kWh is remaining, even though Nissan has said it is 85% of original.

I suspect the difference is that Nissan may consider the original nominal usable capacity to be 20 kWh. This is evidenced by the fact that they instructed their dealers to verify that the car had 19-21 kWh usable if they came in to complain about range. Given that, 85% of 20 kWh is 17 kWh.

BTW, for future reference, after the mishap in August, once your friend unplugged the LEAF, you could have used the remote control for the climate control system to run the battery charge level back down to 30% or so. It will run for two hours npwhen unplugged and then you can launch it again.

 

[madbrain]

BTW, for future reference, after the mishap in August, once your friend unplugged the LEAF, you could have used the remote control for the climate control system to run the battery charge level back down to 30% or so. It will run for two hours npwhen unplugged and then you can launch it again.

Thanks. Why didn't I think of that?

 

[TonyWilliams]

9 bars on your range chart means a state of charge of 70.8 to 77.9%. If my car is really already at 81% max, you would think it would pretty close to losing the 10th bar... Yet it's still showing all 12.

Sadly, no. The Nissan instruments just aren't that good. Sorry.

You could be down to 81%-ish and still have 12 bars.

 

[LEAFfan]

Madbrain, you will lose a CB very soon. Every one that I've tested was around 80%-81% Gids when they lost their first CB, including mine.

 

[madbrain]

9 bars on your range chart means a state of charge of 70.8 to 77.9%. If my car is really already at 81% max, you would think it would pretty close to losing the 10th bar... Yet it's still showing all 12.

Sadly, no. The Nissan instruments just aren't that good. Sorry.

You could be down to 81%-ish and still have 12 bars.

I got the OBDII bluetooth device today and got it working with Leafspy lite.

The app shows AHr=61.49 (93.73%) Health=86.14% , Odo = 9304, QC count = 12, L1/L2 Count = 411 .

 

[madbrain]

9 bars on your range chart means a state of charge of 70.8 to 77.9%. If my car is really already at 81% max, you would think it would pretty close to losing the 10th bar... Yet it's still showing all 12.

Sadly, no. The Nissan instruments just aren't that good. Sorry.

You could be down to 81%-ish and still have 12 bars.

I got the OBDII bluetooth device today and got it working with Leafspy lite.

The app shows AHr=61.49 (93.73%) Health=86.14% , Odo = 9304, QC count = 12, L1/L2 Count = 411 .

I'm not quite sure how to interpret these numbers from Leafspy.

Is it the 93.73% number that matters ? If so, it would indicate that I only lost 6.27%. I find it a little hard to believe given the range I'm getting.

Or is it the 86.14% (battery health) ?

 

[surfingslovak]

Julien, just use the Ahr value instead of GIDs.

AH = 61.49 (93.73%) 
GIDs = 0.9373 x 281 = 263

 

[madbrain]

Julien, just use the Ahr value instead of GIDs.

AH = 61.49 (93.73%) 
GIDs = 0.9373 x 281 = 263

OK. Well, if my battery truly has 93% of the capacity of a new one, I don't think I should be having the sort of experience I have had like I related earlier in this thread.

The meter is interesting though - I just came back from a movie at AMC 20 - the 15.1 mile from my house took the SOC from 93% to 78%, ie it cost 15% SOC or about 1% per mile.

But the return trips, which was only 14.2 miles, dragged the SOC down to 52%. Ie. 26% SOC or only 1.83% per mile.

And yes I drove the same speeds, never exceeding 65mph, using cruise control, for both trips. Even the 19°C temperature was the same outside at midnight and 3am.

The only difference is the downhill vs uphill. There was about 600ft of downhill in the first trip and the same amount of uphill in the return trip.

 

[dgpcolorado]

...The only difference is the downhill vs uphill. There was about 600ft of downhill in the first trip and the same amount of uphill in the return trip.

Yes, hills matter, as you've seen... So does wind, although you may not have had any in the middle of the night.

Being able to measure the energy use over a leg of a trip is informative and fun!

 

[Stoaty]

The only difference is the downhill vs uphill. There was about 600ft of downhill in the first trip and the same amount of uphill in the return trip.

It's only in a BEV (with a decent energy gauge) that you realize what you have been taking for granted in your ICE vehicle--it takes a lot of energy to move a 3000+ pound car up a long hill.

 

[surfingslovak]

The only difference is the downhill vs uphill. There was about 600ft of downhill in the first trip and the same amount of uphill in the return trip.

It's only in a BEV (with a decent energy gauge) that you realize what you have been taking for granted in your ICE vehicle--it takes a lot of energy to move a 3000+ pound car up a long hill.

Indeed. If you like the meter, you might want to invest in the version that shows GIDs and the remaining kWh figure. It's a little more accurate and crisp than the SOC % value. Based on some earlier calculations, I would expect the SOC to drop about 1% for each 100 feet of elevation difference. This assumes like-new battery condition, but you are not all that far from that it seems.

 

[RegGuheert]

I got the OBDII bluetooth device today and got it working with Leafspy lite.

The app shows AHr=61.49 (93.73%) Health=86.14% , Odo = 9304, QC count = 12, L1/L2 Count = 411 .

I'm not quite sure how to interpret these numbers from Leafspy.

Is it the 93.73% number that matters ? If so, it would indicate that I only lost 6.27%. I find it a little hard to believe given the range I'm getting.

Or is it the 86.14% (battery health) ?

Health may actually be important in your case. As the battery degrades, the capacity (Ah) is reduced and the resistance is increased. If you drive at low power levels (gradual acceleration, low speeds and no steep climbs) you will mostly care only about the Ah number. But if you accelerate hard or drive at 70 MPH or up steep grades at high power levels, the the increased resistance will tend to reduce your range more than the Ah reading alone would indicate. Some of us believe (but do not know for sure) the health value may be some calculation which takes both capacity and resistance into consideration. It's possible that value may better predict the range effect the battery has for your driving style/conditions.