12% capacity loss in 9 months is "normal"

[LTLFTcomposite]

Wow, just read through this thread. I know the battery warranty is nebulous but took it on faith that if the battery capacity diminished significantly in a short period Nissan would be all over it for the sake of the image of the vehicle and concerns over wanting satisfied customers.

Next Sunday I'm meeting up with some GCEAA folks at a car show; if it's anything like the other car show I went to I expect to be inundated with questions about the Leaf, which I have always answered positively and forthrightly. After hearing this how am I supposed to recommend it to others knowing that Nissan doesn't really have our backs? This is on top of the grabby brakes problem that also appears to be getting swept under the rug.

The second thoughts over leasing are fading by the minute.

 

[gbarry42]

Continuing on the charger angle, now that it getting noticed, how long does it take to charge from 80 percent to 100? Anything shorter than 90 minutes would be suspect.

 

[TickTock]

Continuing on the charger angle, now that it getting noticed, how long does it take to charge from 80 percent to 100? Anything shorter than 90 minutes would be suspect.

Thanks for the suggestion. I'll let you know tomorrow.

 

[garygid]

I suspect that Ingineer knows how to read those 96 cell-pair voltages, and hopefully his LEAFscan will append them to a CellVoltage report file on the SD card.

Then, we can make these tests anytime we want.

Hopefully he will also read which shunts are ON, so we can avoid reading the cell-pair voltages during "balancing".

 

[Ingineer]

Yes, the balancing system modes for each cell are available. You can watch them cycle on and off.

-Phil

 

[Ingineer]

Since a level 2 charge is on the order of 10 amps DC it seems a 1-A shunt is capable of reducing the charge going into a given cell pair by about 10%. Since there are 96 cell pairs in series, that only comes to about 0.1% of overall charge power per shunt. Do you know how many shunts can be turned on at any one time?

In theory all of them can be, in practice usually not as only some of them need balancing at any given time. I can tell you that they never hit 100% duty cycle though. But if you add a few percent in for this, and all the other losses, I think we're in the ballpark from what I've seen. There are a lot of bad numbers here posted by people, not intentionally, but just from using poor instrumentation.

Lithium Ion charging losses increase near 100% SoC and as the battery gets closer to the top, more of the charge energy is turned into heat rather than stored as potential. That's also when the balancing system is more active.

-Phil

 

[TickTock]

Continuing on the charger angle, now that it getting noticed, how long does it take to charge from 80 percent to 100? Anything shorter than 90 minutes would be suspect.

Last night it took 65 minutes to bring an 80% charge to 100%. Carwings predicted 90.

 

[RegGuheert]

]In theory all of them can be, in practice usually not as only some of them need balancing at any given time. I can tell you that they never hit 100% duty cycle though. But if you add a few percent in for this, and all the other losses, I think we're in the ballpark from what I've seen.

Thanks! That's helpful!

If you also have the ability to measure each of the cell voltages, would you mind running through the "Cell Voltage Loss Inspection" procedure on page EVB-65 of the Service Manual and provide a list or a histogram or the max and min voltages for your Leaf? That would be very interesting to compare with what TickTock's dealer saw and also for everyone in general. I think it will also be interesting to see this kind of data right after a balancing charge to 100% compared with the same data following two weeks or so of only 80% charge.

We all know you are very busy, but I figure it doesn't hurt to ask!

TIA!

 

[vegastar]

Continuing on the charger angle, now that it getting noticed, how long does it take to charge from 80 percent to 100? Anything shorter than 90 minutes would be suspect.

Last night it took 65 minutes to bring an 80% charge to 100%. Carwings predicted 90.

65 minutes means a max of 65/60 * 3.8 = 4,12kW.h from the wall. Probably less because the last 10 minutes are at a reduced current (CV phase). It's a low value, I think. Will check this week in my car the value.

 

[surfingslovak]

Continuing on the charger angle, now that it getting noticed, how long does it take to charge from 80 percent to 100? Anything shorter than 90 minutes would be suspect.

Last night it took 65 minutes to bring an 80% charge to 100%. Carwings predicted 90.

65 minutes means a max of 65/60 * 3.8 = 4,12kW.h from the wall. Probably less because the last 10 minutes are at a reduced current (CV phase). It's a low value, I think. Will check this week in my car the value.

I checked my ChargePoint usage history, and last time I did this, I saw the following:

kWh: 4.826
Time: 01:29:31

 

[vegastar]

65 minutes means a max of 65/60 * 3.8 = 4.12kW.h from the wall. Probably less because the last 10 minutes are at a reduced current (CV phase). It's a low value, I think. Will check this week in my car the value.

I checked my ChargePoint usage history, and last time I did this, I saw the following:

kWh: 4.826
Time: 01:29:31

It's just one datapoint but 4.12/4.826 = 0.85 or a 15% degradation, but probably more because of the lower charge rate in the last 10 minutes.

 

[Stoaty]

It's just one datapoint but 4.12/4.826 = 0.85 or a 15% degradation, but probably more because of the lower charge rate in the last 10 minutes.

Yes, but since we are talking about only the top 20% of the pack, the degradation amount applied to the whole pack would be just 3%. Doesn't really give any useful info.

 

[IBELEAF]

Interesting, so for people who don't have Gid meter, is this a good way to determine degradation? normal 80% charge to 100% at 1.5 hours?

 

[GaslessInSeattle]

seems questionable to me since core temp of battery can effect charge rate.

Interesting, so for people who don't have Gid meter, is this a good way to determine degradation? normal 80% charge to 100% at 1.5 hours?

 

[IBELEAF]

seems questionable to me since core temp of battery can effect charge rate.

Interesting, so for people who don't have Gid meter, is this a good way to determine degradation? normal 80% charge to 100% at 1.5 hours?

Why not? What if you let the car sit for a few hours before starting your charge from 80% assuming that ambient temperature is the same. I just checked my logs where I do 80% to 100% charges once a week and it shows in all my charges done around 90 minutes. Wouldn't that be enough indication that there is no major degradation?

 

[vegastar]

It's just one datapoint but 4.12/4.826 = 0.85 or a 15% degradation, but probably more because of the lower charge rate in the last 10 minutes.

Yes, but since we are talking about only the top 20% of the pack, the degradation amount applied to the whole pack would be just 3%. Doesn't really give any useful info.

As the 80% and 100% are voltage based, the degradation can be extrapolated, to some extent, to the rest of the SOC.

 

[DaveEV]

Last night it took 65 minutes to bring an 80% charge to 100%. Carwings predicted 90.

65 minutes means a max of 65/60 * 3.8 = 4,12kW.h from the wall. Probably less because the last 10 minutes are at a reduced current (CV phase). It's a low value, I think. Will check this week in my car the value.

I checked my ChargePoint usage history, and last time I did this, I saw the following:
kWh: 4.826
Time: 01:29:31

My last 80-100% charge a couple weeks ago according to my Blink (I've only done a handful at most and think I've only let the car sit on 100% charge for any period of time once I got the car to balance):
kWh: 4.667
Time: 1:25:25

Will see if my Blink recorded any other 80-100% charges...

Edit: Previous one a couple months ago:
kWh 4.959
Time: 1:28:35

 

[gbarry42]

Unfortunately, I can think of more than one reason for the charge time to be shortened.

• - It may be that the battery capacity is less, and therefore is "filled" sooner.
  - It may be that the charger is not working properly, and terminates the charge too soon.
  - It may be that a sensor is getting a wrong reading. This is similar to the one about the charger, but since we have to explain why it still goes to "12 bars", a bad sensor could explain both. How low can the charge level be, and still read 12 bars?

Well, now I'm thinking of a test to see how much you get out of bar #12. I also will state my opinion that the failure of one module is a reasonable probability, but the significant degradation of all 48 at the same time and in the same way is not. Not impossible, but I'd go there after exhausting all the other theories. The normal behavior up to 80% seems to discount this as well.

Since the power input tapers off during the end of charge, it makes it kind of hard to know things just based on time. I did some searching and found that about 4.5 kwh goes in from 80 to 100%. I was looking for a nice graph of it, but that's harder to locate.

 

[vegastar]

The bars are adjusted so that a battery with 50% degradation still shows 12 charge bar, but each represents a lower energy.

 

[IBELEAF]

The bars are adjusted so that a battery with 50% degradation still shows 12 charge bar, but each represents a lower energy.

I thought it was mentioned several times that bars would stop lighting up, so essentially leave you with 6 bars with 50% degradation...