8 bar battery replacement metrics

[fooljoe]

In discussing with a very EV Savvy friend about how might be estimating battery capacity at any given time, he suggested that one way would be for them to integrate Amps for a given time (thereby getting Ah), looking for the point at which the battery voltage drops a given amount (thereby essentially having a Ah vs. V plot), and then comparing that to the expected for a new LEAF battery. If that is true, then part of their Algorithm could be that no data are collected unless the battery is discharged for sufficient time during one charge/discharge cycle. If this is true, then a statement like "my last 10 charges have reach an Ah or GID value BELOW the bottom end of the 9th bar, and it hasn't dropped off" would be misguided. Perhaps most of those charges were not even counted by Nissan's Algorithm, due to insufficient discharge time before recharging. It's food for thought! Does anyone know how LEAF-Spy estimates capacity on a fully charged LEAF Battery?

Let me try to correct a few misconceptions here:

Ah and Gids can't be used interchangeably. Ah is independent of state of charge (SOC, or "percent full"), so the Ah (capacity) of a battery is the same whether a battery is empty of fully charged. A 10 gallon tank is a 10 gallon tank regardless of how many gallons are currently in it. Gids are a measure of energy, so they're affected by both SOC and Ah - Gids show how many "gallons" are currently in the tank.

LeafSpy doesn't estimate capacity; it simply spits out metrics that are entirely generated by Nissan hardware and software and passed around on the car's internal network.

It's likely true that something like the method your friend described is used to come up with the car's internal estimate of capacity (i.e. Ah). But how Ah is estimated is not the question here. The question is how the car's controller that determines bar loss uses the Ah estimate (and probably other data as well - but all data that we'd expect to be able to see via LeafSpy-like tools) to determine when to stop displaying a bar.

 

[iamchemist]

In discussing with a very EV Savvy friend about how might be estimating battery capacity at any given time, he suggested that one way would be for them to integrate Amps for a given time (thereby getting Ah), looking for the point at which the battery voltage drops a given amount (thereby essentially having a Ah vs. V plot), and then comparing that to the expected for a new LEAF battery. If that is true, then part of their Algorithm could be that no data are collected unless the battery is discharged for sufficient time during one charge/discharge cycle. If this is true, then a statement like "my last 10 charges have reach an Ah or GID value BELOW the bottom end of the 9th bar, and it hasn't dropped off" would be misguided. Perhaps most of those charges were not even counted by Nissan's Algorithm, due to insufficient discharge time before recharging. It's food for thought! Does anyone know how LEAF-Spy estimates capacity on a fully charged LEAF Battery?

Let me try to correct a few misconceptions here:

Ah and Gids can't be used interchangeably. Ah is independent of state of charge (SOC, or "percent full"), so the Ah (capacity) of a battery is the same whether a battery is empty of fully charged. A 10 gallon tank is a 10 gallon tank regardless of how many gallons are currently in it. Gids are a measure of energy, so they're affected by both SOC and Ah - Gids show how many "gallons" are currently in the tank.

LeafSpy doesn't estimate capacity; it simply spits out metrics that are entirely generated by Nissan hardware and software and passed around on the car's internal network.

It's likely true that something like the method your friend described is used to come up with the car's internal estimate of capacity (i.e. Ah). But how Ah is estimated is not the question here. The question is how the car's controller that determines bar loss uses the Ah estimate (and probably other data as well - but all data that we'd expect to be able to see via LeafSpy-like tools) to determine when to stop displaying a bar.

So, are you saying that there is no data available from a LeafSpy that will effectively act as a "gas gauge" for a LEAF? That is, if your battery has 60% of its new capacity (I believe that would be 39.75 Ah) remaining and you charge it fully, then a LeafSpy will simply continue to tell you 39.75 Ah as you drive and run the battery down?

I don't agree that "how Ah is estimated is not the question". That's like saying it doesn't matter how data are generated, but only how I process it afterwards. Both things matter a great deal to what final value is arrived at. Like I said, it is common to see a statement on this Forum like "my last 20 charges have yielded an Ah capacity value that is below the expected value for the bottom of the 9th bar, but it hasn't yet disappeared". Unless we know Nissan's criteria for determining capacity, than we have no idea whether such a statement makes any sense. It could look like there is a huge range of Ah capacity over which a bar disappears, when the range is really very tight, but we don't know what data counts.

 

[TimLee]

So, are you saying that there is no data available from a LeafSpy that will effectively act as a "gas gauge" for a LEAF? ...

It reports four values that relate to energy stored in the pack.

Remaining kWh:
Pack will disconnect at 0.3 kWh.
So if you know how many miles per kWh you are getting based on speed, elevation change, driving practices, HVAC use, etc you know how far you can go.
It also gives you miles based on miles per kWh you set and threshold you pick either LBW, VLBW, Or reserve kWh you select.

GIDS:
A Nissan measure of stored energy

% SOC:
Based on theoretical maximum and minimum cell voltages.
Full on a LEAF is 93% to 94% range.
Empty is usually near or below 0% when pavk disconnects.

% GIDS:
LEAF Spy calculates GIDS divided by Maximum GIDS for a fully charged new pack with no capacity degradation

 

[fooljoe]

% GIDS:
Leaf Spy calculates GIDS divided by MAX GIDS for a new pack with no capacity degradation

FTFY

So, are you saying that there is no data available from a LeafSpy that will effectively act as a "gas gauge" for a LEAF? That is, if your battery has 60% of its new capacity (I believe that would be 39.75 Ah) remaining and you charge it fully, then a LeafSpy will simply continue to tell you 39.75 Ah as you drive and run the battery down?

That's correct - Ah stays fixed as you drive and run the battery down. Each time you start the car up or charge the estimate moves a little bit, but how it moves is not related to what your SOC is at the time. There are data available from LeafSpy that will act as a "gas gauge", as Tim pointed out, but Ah is not included in that list. Ah tells you the size of the tank, not how much is in it.

I don't agree that "how Ah is estimated is not the question". That's like saying it doesn't matter how data are generated, but only how I process it afterwards. Both things matter a great deal to what final value is arrived at. Like I said, it is common to see a statement on this Forum like "my last 20 charges have yielded an Ah capacity value that is below the expected value for the bottom of the 9th bar, but it hasn't yet disappeared". Unless we know Nissan's criteria for determining capacity, than we have no idea whether such a statement makes any sense. It could look like there is a huge range of Ah capacity over which a bar disappears, when the range is really very tight, but we don't know what data counts.

We don't know how exactly Nissan computes the Ah number or other numbers we read via LeafSpy and the like, but we know that it's a pretty accurate measure of capacity by comparing its predictions to what we see via range tests. So if your Ah value (or the related SOH percentage) indicates you're at 65% capacity, it's a good bet that you actually are. But as I often advocate in here, if you want to complain to Nissan you should back your claims with actual range tests and not LeafSpy numbers.

The "expected value for the bottom of the 9th bar" can be interpreted in a number of different ways: If your expectation is based on the language of the settlement that indicates it should correspond to "about 70%" capacity, then you'd expect to see the bar drop at around 46.4 Ah (and you'll be very disappointed.) If your expectation is based on Nissan statements referenced elsewhere that the lower limit of the 9th bar corresponds to 66.25% capacity, then you'd expect to see the bar drop at 43.9 Ah (you'll still be disappointed.)

So if your expectation is at all based upon "official" statements or documents then you'll be disappointed. However, if you base your expectation upon what drivers have reported in here (anywhere from roughly 41.5-43.5 Ah), you'll have a very realistic expectation, but you'll still be pissed at Nissan since that means you must expect your capacity to fall as low as 62.5% before your car becomes eligible. And you'll be very confused as to how there could be such a wide spread in reported Ah values at which the bar drops.

 

[TimLee]

^^^ 62.5% is quite a lot less than 70%.
If Nissan claims in the settlement could be demonstrated to be fraudulent, would that be a basis to petition the Federal Court to throw out the settlement, and force the parties to start all over :?: :shock:

 

[iamchemist]

% GIDS:
Leaf Spy calculates GIDS divided by MAX GIDS for a new pack with no capacity degradation

FTFY

So, are you saying that there is no data available from a LeafSpy that will effectively act as a "gas gauge" for a LEAF? That is, if your battery has 60% of its new capacity (I believe that would be 39.75 Ah) remaining and you charge it fully, then a LeafSpy will simply continue to tell you 39.75 Ah as you drive and run the battery down?

That's correct - Ah stays fixed as you drive and run the battery down. Each time you start the car up or charge the estimate moves a little bit, but how it moves is not related to what your SOC is at the time. There are data available from LeafSpy that will act as a "gas gauge", as Tim pointed out, but Ah is not included in that list. Ah tells you the size of the tank, not how much is in it.

I don't agree that "how Ah is estimated is not the question". That's like saying it doesn't matter how data are generated, but only how I process it afterwards. Both things matter a great deal to what final value is arrived at. Like I said, it is common to see a statement on this Forum like "my last 20 charges have yielded an Ah capacity value that is below the expected value for the bottom of the 9th bar, but it hasn't yet disappeared". Unless we know Nissan's criteria for determining capacity, than we have no idea whether such a statement makes any sense. It could look like there is a huge range of Ah capacity over which a bar disappears, when the range is really very tight, but we don't know what data counts.

We don't know how exactly Nissan computes the Ah number or other numbers we read via LeafSpy and the like, but we know that it's a pretty accurate measure of capacity by comparing its predictions to what we see via range tests. So if your Ah value (or the related SOH percentage) indicates you're at 65% capacity, it's a good bet that you actually are. But as I often advocate in here, if you want to complain to Nissan you should back your claims with actual range tests and not LeafSpy numbers.

The "expected value for the bottom of the 9th bar" can be interpreted in a number of different ways: If your expectation is based on the language of the settlement that indicates it should correspond to "about 70%" capacity, then you'd expect to see the bar drop at around 46.4 Ah (and you'll be very disappointed.) If your expectation is based on Nissan statements referenced elsewhere that the lower limit of the 9th bar corresponds to 66.25% capacity, then you'd expect to see the bar drop at 43.9 Ah (you'll still be disappointed.)

So if your expectation is at all based upon "official" statements or documents then you'll be disappointed. However, if you base your expectation upon what drivers have reported in here (anywhere from roughly 41.5-43.5 Ah), you'll have a very realistic expectation, but you'll still be pissed at Nissan since that means you must expect your capacity to fall as low as 62.5% before your car becomes eligible. And you'll be very confused as to how there could be such a wide spread in reported Ah values at which the bar drops.

Well, it seems to me that you have come full circle, which is a good thing, since I believe that your contention that Ah and GID's can't be compared is dead wrong. Ah X V = Wh, which is proportional to GID's, Or to be more accurate, you would integrate the area under the Ah vs. V curve that you get as you discharge a LEAF battery. The voltage of a fully charged LEAF battery is 364.8 V. As you state "So if your Ah value (or the related SOH percentage) ...". Yes, SOH is related closely to Ah and is proportional to % GID. You see, a 20 gallon fuel tank is always a 20 gallon fuel tank, but it is the amount of fuel in the tank (read energy, SOH, %GID) that is related to the range you can get. This close relationship with Ah is why you will see many posts on this Forum that say things like "I lost my 10th Capacity Bar at n Ah.

 

[fooljoe]

Well, it seems to me that you have come full circle, which is a good thing, since I believe that your contention that Ah and GID's can't be compared is dead wrong.

Obviously Ah and GIDs should be related, since they're both metrics describing the same pack! I'm not sure exactly what you're referencing about what I said before, but most likely I was just trying to make sure it's clear that GIDs vary with SOC while Ah doesn't.

The voltage of a fully charged LEAF battery is 364.8 V.

No, it's 390-something Volts when fully charged.

You see, a 20 gallon fuel tank is always a 20 gallon fuel tank, but it is the amount of fuel in the tank (read energy, SOH, %GID) that is related to the range you can get.

This is why I again must stress how Ah and GIDs are different - SOH does not belong in this grouping, as it's a measure of the size of the tank, not how much fuel is in it. Perhaps you meant to say SOC.

many posts on this Forum that say things like "I lost my 10th Capacity Bar at n Ah."

This is what they should be saying, as Ah is the correct metric to reference with respect to the capacity bars.

 

[bmetzner]

Hi. I have a 2012 Nissan Leaf SL which I purchased used 3 months ago with 10 capacity bars. It has just lost another bar, I'm down to 9.

I called Nissan EV and they said battery will be replaced if it goes to 8 bars by 12/14/16. They also seemed pretty confident that I would lose the next bar before the warranty expired.

The car has 25,000 miles on it. I live in Florida and anticipate putting about 8,000 miles on it over the next year.

My questions are:
1. What are the chances of losing that ninth bar over the next 13 months?
2. Is there anything I can do to improve my chances?

Thanks,
Bill
(I don't have LeafSpy, but I'm getting it set up next week.)

 

[dhanson865]

Hi. I have a 2012 Nissan Leaf SL which I purchased used 3 months ago with 10 capacity bars. It has just lost another bar, I'm down to 9.

I called Nissan EV and they said battery will be replaced if it goes to 8 bars by 12/14/16. They also seemed pretty confident that I would lose the next bar before the warranty expired.

The car has 25,000 miles on it. I live in Florida and anticipate putting about 8,000 miles on it over the next year.

My questions are:
1. What are the chances of losing that ninth bar over the next 13 months?
2. Is there anything I can do to improve my chances?

Thanks,
Bill
(I don't have LeafSpy, but I'm getting it set up next week.)

To increase degradation and get your new pack sooner or to increase the odds of getting the pack at all in Florida


* Park in the Sun not in the shade whenever possible
* Park on the hottest material (asphalt vs concrete vs dirt and so on)
* Park inside or outside (garage vs driveway) based on which one stays hotter in the middle of the night.
* Charge to 100% not 80%
* Drive as fast as you want, don't conserve energy
* Charge as often as you can keep the pack recharged
* Run your AC set to 60F if you can stand the cold. No reason for the cabin to be hot, the pack is under the car.

You could do more but it doesn't sound like you'll need to.

 

[QueenBee]

2. Is there anything I can do to improve my chances?

To increase degradation and get your new pack sooner or to increase the odds of getting the pack at all in Florida

You could do more but it doesn't sound like you'll need to.

One thing not to do is:
"This warranty does not cover damage or failures resulting from or caused by:..Physically damaging the lithium-ion battery or intentionally attempting to reduce the life of the lithium-ion battery."

 

[dhanson865]

2. Is there anything I can do to improve my chances?

To increase degradation and get your new pack sooner or to increase the odds of getting the pack at all in Florida

You could do more but it doesn't sound like you'll need to.

One thing not to do is:
"This warranty does not cover damage or failures resulting from or caused by:..Physically damaging the lithium-ion battery or intentionally attempting to reduce the life of the lithium-ion battery."

Yes warranty voiding actions would be something like

* Putting your car in a paint bake oven
* Driving your car to death valley national park just to leave it in the sun at 130F or so
* Exposing the battery pack to flames
* Placing heat lamps or a heat blanket under the car specifically to heat the pack in the spring/summer/fall.

There are many actions that a Leaf owner can take to reduce or increase degradation rates that aren't specifically under the category of fine print you mentioned because they have a practical real world purpose in the use of the car.

You just have to be sure that you don't cross the line between using the car and destroying the battery pack.

 

[GerryAZ]

Hi. I have a 2012 Nissan Leaf SL which I purchased used 3 months ago with 10 capacity bars. It has just lost another bar, I'm down to 9.

I called Nissan EV and they said battery will be replaced if it goes to 8 bars by 12/14/16. They also seemed pretty confident that I would lose the next bar before the warranty expired.

The car has 25,000 miles on it. I live in Florida and anticipate putting about 8,000 miles on it over the next year.

My questions are:
1. What are the chances of losing that ninth bar over the next 13 months?
2. Is there anything I can do to improve my chances?

Thanks,
Bill
(I don't have LeafSpy, but I'm getting it set up next week.)

Bill,
Others have already given you some advice on increasing the chance of losing the ninth bar by maximizing heat in the battery. Here are my thoughts: You have plenty of miles and over a year to lose the ninth bar so I am sure you will qualify for a new battery. If your car has not received the P3227 software update, you should have the dealer perform that update as soon as you can schedule it. Since you have plenty of miles left on the battery capacity warranty, try to use the Leaf as much as you can. Charge to 100% each charge and don't be afraid to run it down to low battery warning or very low battery warning to maximize cycling of the battery. On my 2011, I lost the 12th bar a little over one year after purchase and the 11th bar a month or so later. The 10th bar dropped a little over two years after purchase and the 9th bar dropped a month or so after that.

Gerry

 

[QueenBee]

Hi. I have a 2012 Nissan Leaf SL which I purchased used 3 months ago with 10 capacity bars. It has just lost another bar, I'm down to 9.

I called Nissan EV and they said battery will be replaced if it goes to 8 bars by 12/14/16. They also seemed pretty confident that I would lose the next bar before the warranty expired.

The car has 25,000 miles on it. I live in Florida and anticipate putting about 8,000 miles on it over the next year.

My questions are:
1. What are the chances of losing that ninth bar over the next 13 months?
2. Is there anything I can do to improve my chances?

Thanks,
Bill
(I don't have LeafSpy, but I'm getting it set up next week.)

Bill,
Others have already given you some advice on increasing the chance of losing the ninth bar by maximizing heat in the battery. Here are my thoughts: You have plenty of miles and over a year to lose the ninth bar so I am sure you will qualify for a new battery. If your car has not received the P3227 software update, you should have the dealer perform that update as soon as you can schedule it. Since you have plenty of miles left on the battery capacity warranty, try to use the Leaf as much as you can. Charge to 100% each charge and don't be afraid to run it down to low battery warning or very low battery warning to maximize cycling of the battery. On my 2011, I lost the 12th bar a little over one year after purchase and the 11th bar a month or so later. The 10th bar dropped a little over two years after purchase and the 9th bar dropped a month or so after that.

Gerry

Is getting the update a good idea and required at this point? I would expect it to improve the accuracy of the SOH which I would read as taking longer for SOH to decrease. I'm not sure if not having it done would cause any concern with regards to warranty coverage but one would expect it to be done when the battery is replaced.

 

[GerryAZ]

My 2011 got down to a little over 40 AHr before it lost the 9th bar (prior to having the software update). I believe most are seeing the 9th bar drop around 43 AHr after the update. If Bill has the update done now, any artificial increase in capacity numbers will be dissipated long before his warranty expires. If his car goes to the dealer for anything else closer to warranty expiration, the dealer will do the software update then and the numbers may not stabilize before the warranty expires. Therefore, I think it is best to make sure the software update is done sooner rather than later. Also, the dashboard instrumentation will be more accurate after the update.

Gerry

 

[TimLee]

With a year to go for Bill having it done early is probably better approach.

But it may cause some regeneration loss.

If the tech does just P3227 it is unlikely that capacity bars will be gained.
But some techs are idiots and also end up doing the clearing of all capacity loss data.

If they do that , it could eliminate all the loss of capacity bars and might take more than six months to be accurate again.

So someone like myself that only has about six months to capacity warranty runs out may be better off to wait and lose four capacity bars first.

Yes Nissan probably will then require P3227 be done.
But having already lost four bars there will be some better chance to get pack replacement.
If the tech messes up and clears all capacity loss data, then there would be very little chance to lose four capacity bars in time.

 

[bmetzner]

Thank you all. I am not going to do anything malicious, just wanted some thoughts. I have instructed my wife to USE the car!
I have level 2 chargers at work which I leave it plugged into most of the day 4 days a week...

I had the car to Nissan dealer a 6 weeks ago for a check out after purchasing used. It had 10 capacity bars at that time.
They did the brake fluid, wipers, and said everything else was good.

I'll let you know what the readings are when I get LeafSpy running.

 

[Reddy]

Be a "spirited driver", accelerating with gusto at each green light, drive fast, slam on the brakes, etc. Hmmm, sounds like you should drive it with an EV grin all the time.

 

[QueenBee]

Be a "spirited driver", accelerating with gusto at each green light, drive fast, slam on the brakes, etc. Hmmm, sounds like you should drive it with an EV grin all the time.

Wait, isn't that every LEAF driver does?

 

[bmetzner]

OK. I got LeafSpy running. Here's what I see right now:
AHr=47.64
SOH=72% 379.OV
Hx =66.11%

I have 9 bars, 25,726 miles on odometer and 376 days until 5 years.

 

[kolmstead]

You're going to have a difficult time qualifying for the capacity warranty. Some folks manage to lose 9th bar with 43.75 Ahr capacity, but the majority lose it around 43.3. Some batteries have run down into the high 41s before losing 9th bar. So you have about a year to lose 4 to 6 Ahr, and virtually all of that has to happen in the summer. A typical hot climate loss would be 3-4 Ahr per year.

High battery temperatures are the key; below 85 degrees F, degradation is very slow. Driving hard (uphill or fast), recharging immediately and using L3 charging whenever available will keep that battery hot. Good luck.

-Karl