2019 Leaf battery overheating

[metricus]

First of all Dave i want to thank you for the many studies you did on your blog and the answers to this post. I read through all of them.

Yes I understand how batteries work. I am an engineer and my frustration is that the battery pack is by all indications thermally unbalanced. As I said before such engineering blunders are unacceptable this day and age.

On top of everything comes Nissan's whitewash. There are multiple examples where they make it sound like you can QC and drive. They do say it's not recommended for extended use but they never say that the 50kW advertised or even any speed above 40kW is practically impossible to achieve under normal driving conditions.

Just like you, I too take maximum precautions, I use cruise control, Eco, shade parking etc. etc. but it only reduces the problem to some extent.

The reality is that the car puts heat in while in use with no way to get it out so you are effectively driving to a "slow death".

The gauge's design tells a story in itself. The 6th TB has a far larger range and hysteresis than the other jumps. it is clear they did this on purpose to give the impression of thermal balance. Only by reading the actual sensors through LeafSpy you get the real picture of constant heat gain.

At the and of the day the problem is that the car has limited daily range and Nissan never discloses that. This should not be an information that the customer finds out only after the sale.

 

[GerryAZ]

It sounds like the 40 kWh battery has higher internal resistance than the earlier ones (based upon the fact that temperature goes up more while driving). My 2015 battery temperature would drop while driving on the highway after a quick charge until recently. It now increases because the internal resistance is higher (which causes several issues): The higher internal resistance results in more voltage drop under load which makes the motor draw more current for a given power draw; the extra current causes more voltage drop which causes the motor to draw even more current so the SOC drops even faster. The net effect is greatly reduced range under higher power consumption operation (highway driving or going uphill). Another effect is higher average battery temperature this spring compared to previous years under the same driving conditions.

Since my 2015 has some weak cell pairs and generally higher internal resistance than before (just turned up 79,000 miles), regeneration is reduced and quick charging rate is also reduced (similar to what is being described in this thread for 40 kWh batteries). I my case, it appears that the LBC (lithium battery controller) is limiting charging current (either from DCQC or regeneration) to avoid exceeding maximum voltage on weak cells. It also limits depth of discharge since the weaker cells reach minimum allowable voltage while the remaining cells have a lot of energy left.

 

[lorenfb]

It sounds like the 40 kWh battery has higher internal resistance than the earlier ones (based upon the fact that temperature goes up more while driving). My 2015 battery temperature would drop while driving on the highway after a quick charge until recently. It now increases because the internal resistance is higher (which causes several issues): The higher internal resistance results in more voltage drop under load which makes the motor draw more current for a given power draw; the extra current causes more voltage drop which causes the motor to draw even more current so the SOC drops even faster. The net effect is greatly reduced range under higher power consumption operation (highway driving or going uphill). Another effect is higher average battery temperature this spring compared to previous years under the same driving conditions.

Remember, the internal battery resistance has a negative temperature coefficient, i.e. the higher battery temperature, the lower will
be its resistance. That somewhat offsets the potentially higher voltage drop from higher motor currents.

 

[metricus]

Please, do not forget to sign the petition to put pressure on Nissan to make the upgrade available to North-Americas customer.
https://www.change.org/p/nissan-north-america-fix-rapidgate-for-early-2018-leaf-buyers

I signed the petition and chipped in my part. Hope it helps.

Also, in case anyone was losing any sleep over this, Nissan called today and denied me the repurchase request on the basis that it has not been in the shop as required by law. The shop on the other hand acknowledged the issue but wrote nothing about it on the service report. Bunch of BS.

Anyone knows a good lawyer?

 

[lorenfb]

Please, do not forget to sign the petition to put pressure on Nissan to make the upgrade available to North-Americas customer.
https://www.change.org/p/nissan-north-america-fix-rapidgate-for-early-2018-leaf-buyers

I signed the petition and chipped in my part. Hope it helps.

It's highly doubtful that Nissan would ever increase its potential battery liabilities by approving such a request.

 

[GerryAZ]

Remember, the internal battery resistance has a negative temperature coefficient, i.e. the higher battery temperature, the lower will
be its resistance. That somewhat offsets the potentially higher voltage drop from higher motor currents.

Not necessarily, it depends upon the situation. Internal resistance of the pouch cells in good condition decreases with increasing temperature. Resistance of the connections between cells increases with increasing temperature. Also, internal resistance of deteriorated cells increases with increasing temperature under high load conditions (probably due to plating on electrodes causing reduced effective surface area).

 

[lorenfb]

Remember, the internal battery resistance has a negative temperature coefficient, i.e. the higher battery temperature, the lower will
be its resistance. That somewhat offsets the potentially higher voltage drop from higher motor currents.

Not necessarily, it depends upon the situation. Internal resistance of the pouch cells in good condition decreases with increasing temperature. Resistance of the connections between cells increases with increasing temperature. Also, internal resistance of deteriorated cells increases with increasing temperature under high load conditions (probably due to plating on electrodes causing reduced effective surface area).

The reference was for the typical occurrence, e.g. connection resistance is minor. And your data reference for deteriorated cells is?
Surely you've complied battery resistance over the years on your two Leafs that you can present, right?

 

[GerryAZ]

Based upon voltage drop under full load (80 kW) at similar battery temperatures, the internal resistance of the 2015 battery has essentially doubled since it was new (79,000 miles and almost 52 months of use). I did not have appropriate instrumentation to measure it on the original battery in the 2011 and the car was totaled before there was enough deterioration of the replacement battery to make it noticeable.

 

[lorenfb]

Based upon voltage drop under full load (80 kW) at similar battery temperatures, the internal resistance of the 2015 battery has essentially doubled since it was new (79,000 miles and almost 52 months of use). I did not have appropriate instrumentation to measure it on the original battery in the 2011 and the car was totaled before there was enough deterioration of the replacement battery to make it noticeable.

My 2013 latest numbers:

11/20/14 -13,700 miles, 76 mohms per LeafDD, 20 Deg, 73% SOC
11/27 -13,800 miles, 67 mohms per LeafDD, 25 deg, 63% SOC
11/30 - 13,900 miles, 56 mohms per LeafDD, 27 deg, 71% SOC
12/2 - 14.100 miles, 55 mohms per LeafDD, 28 deg, 67% SOC
12/16 - 14,500 miles, 89 mohms per LeafDD, 15 deg, 93% SOC
12/27/14 - 14,800 miles, 103 mohms per LeafDD, 11 deg, 24% SOC
3/10 - 17,400 miles, 60 mohms per LeafDD, 30 deg, 73% SOC
3/14 - 17, 550 miles, 56 mohms per LeafDD, 32 deg, 47% SOC
4/14 - 19,100 miles, 59 mohms per LeafDD, 25 deg. 38% SOC
5/4 - 19,989 miles, 64 mohms per LeafDD, 24 deg. 48% SOC
5/15 - 20,400 miles, 73 mohms per LeafDD, 20 deg. 41% SOC
5/22 - 20,700 miles, 58 mohms per LeafDD, 28 deg. 50% SOC
12/10/15 - 28,000 miles, 90 mohms per LeafDD, 19 deg. 92% SOC
4/5 - 32,000 miles, 74 mohms per LeafDD, 24 deg, 55% SOC
5/16 - 33,700 miles, 89 mohms per LeafDD, 22 deg, 47% SOC
5/16 - 33.700 miles, 58 mohms per LeafDD, 31 deg, 76% SOC
10/5 - 39,300 miles, 100 mohms per LeafDD, 22 deg, 50% SOC
10/6 - 39,400 miles, 61 mohms per LeafDD, 30 deg, 51% SOC
10/7 - 39,500 miles, 80 mohms per LeafDD, 25 deg, 56% SOC
10/15 - 40,000 miles, 71 mohms per LeafDD, 27 deg, 45% SOC
10/30 - 41,000 miles, 74 mohms per LeafDD, 23 deg, 66% SOC
12/26/16 - 43,000 miles, 110 mohms per LeafDD, 13 deg, 77% SOC
6/10/17 - 49,600 miles, 89 mohms per LeafDD, 19 deg, 70% SOC
7/1/17 - 51,000 miles, 62 mohms per LeafDD, 33 deg, 44% SOC
8/15/17 - 53,400 miles, 61 mohms per LeafDD, 35 deg, 57% SOC
4/2/18 - 62,100 miles, 110 mohms per LeafDD, 18 deg, 94% SOC
6/13/18 - 65,000 miles, 84 mohms per LeafDD, 26 deg, 52% SOC
8/13/18 - 67,000 miles, 80 mohms per LeafDD, 26 deg, 91% SOC
9/14/18 - 68,000 miles, 84 mohms per LeafDD, 27 deg, 57% SOC
10/30/18 - 70,000 miles, 93 mohms per LeafDD, 22 deg, 84% SOC
11/9/18 - 70,000 miles, 104 mohms per LeafDD, 22 deg, 89% SOC
11/30/18 - 70,400 miles, 88 mohms per LeafDD, 23 deg, 88% SOC
12/6/18 - 70,800 miles, 116 mohms per LeadDD, 13 deg, 33% SOC
1/30/19 - 72,300 miles, 86 mohms, per LeadDD, 23 deg, 45% SOC
5/29/19 - 74,476 miles, 102 mohms, per LeafDD, 19 deg, 89% SOC

So based on the last data point, the battery output would have dropped about 20 volts (200 amps) during the peak current load
for a battery resistance test.

Wish Turbo3 would update LeafSpy to do the resistance calculation, as he indicated, similar to TM-Spy (Tesla version).

 

[metricus]

It's highly doubtful that Nissan would ever increase its potential battery liabilities by approving such a request.

This also has something to do with how people mobilize and act. I have a feeling that many who purchased the Gen2 Leaf shy from sharing real data out of fear of creating an unfavorable picture of the car which would clearly affect their resale value.

In other words if word goes out Gen2 is a lemon they will be stuck with it.

The reality is that Gen2 is a lemon and eventually the word will go out. My experience matches DaveInOleyWA's. I too had a late Gen1 Leaf which clearly had no problem QCing multiple times per trip. I too consider it the best Leaf I ever had.

From my viewpoint I don't care if the residual value goes down in 2 years, but I understand that not everyone shares it.

What I don't understand is why people come on forums to share incomplete data or to throw dust in our eyes. It must be a staple of the times we live in or they really don't have better things to do with their life.

Finally I agree with lorenfb that Nissan would face higher battery liability if it would update to the EU software. The changed curve does not fix the overheating issue and allowing the car to charge at higher speeds would only result in more cooked batteries and more people stranded in turtle mode.

All they can do at this point is harass the customers who complain by "not understanding" what the problem is.

They set me up from the moment I called in. They sent me to the dealer who kept my car overnight and drove it for 50 miles or so and concluded it's fine.
They never addressed my complaint because they "cannot pay a mechanic do drive it 200 miles". So I was in a vicious circle.

So in essence the 150 miles range per day is all you can REALLY count on driving with the Gen2 Leaf. Anything over this is questionable and may cost you unplanned loss of time. At around 235 miles or so, you are really facing red temp gauge and turtle mode so don't even think of it unless you have nothing better to do.

 

[SageBrush]

They set me up from the moment I called in. They sent me to the dealer who kept my car overnight and drove it for 50 miles or so and concluded it's fine.

Was there a bill ( I won't ask about a charge since I'm pretty sure I know the answer to that question :roll: )

 

[metricus]

Service report not a bill. Zero charge.

Quote:

'CUSTOMER REQUESTS PERFORM NISSAN LEAF LI-ION BATTERY CAPACITY CHECK. CUSTOMER STATES THE BATTERY OVER HEATED AND NOW IS CHARGING HALF WAY. NOTES BATTERY TEMP WOULD RISE WHEN CHARGE IS LESS THAN 25% AND WILL NOT TAKE QUICK CHARGE.
TECH PERFORMED TEST DRIVE; WAS UNABLE TO DUPLICATE CONDITION. RAN CONSULT TEST TO FIND NO CODES STORED.PUT ON CHARGER - FOUND CHARGING AT PROPER AMPS. PERFORMED EXTENDED OVERNIGHT TEST-DRIVE PROPER PERFORMANCE FOUND, AND PERFORMED QUICK CHARGE TUESDAY AM - FOUND RECHARGING AT PROPER AMPS.
--- PERFORMED BATTERY CAPACITY STATUS REPORT - SEE PRINTOUT- NO REPAIR REQUIRED AT THIS TIME."

To be noted that I was pissed that they drove my car extensively without my permission. Also I explained the Service Manager that only a long test drive would show the problem. After I picked-up the car I went to the Newark Airport trip I described in my first post and returned to the dealer with hot batt and they saw that it was charging at 27 kW. I also emailed the Service manager my pictures from the trip home when gauge went on red and charge was throttled to 14kW.

However they did not open a new service request because 'they cannot have the mechanic drive the car for 200 miles" and nissan says no service problem no repurchase. So there!

 

[SageBrush]

hmmm ...
Ask the dealership to test drive and then charge the same day you bring it in. Drive beforehand to heat up the battery to a nice "normal" range.
After all, your contention is that charging is hobbled even when the car is within normal operating parameters.

Does the dealership use DCFC for the test ? Or was the "amperage as expected" from L2 ?

 

[metricus]

They used QC but after car rested overnight.

First challenge is that you show up, explain the problem, and they write whatever the want or understand in that report. Those service reps have no understanding of what I'm talking about. I never complained that the battery's capacity (SOH) is reduced.

In the end the Manager understood the problem took photos of my reduced charge rate and forwarded his findings to Nissan. However Nissan obviously ignored all this.

I need to make a written request with clear complaints and leave it there until they fix it.

Yes, under normal circumstances this car can never DC charge at the advertised rate. If you leave home fully charged and drive until you need to charge again your battery temp is already high enough to throttle charge considerably (low 30s) even when driving in 12C weather.

The only way to get a high rate of charging is if you leave it discharged in the garage and DC charge first thing in the morning before your trip. But then you are really hot at start of trip and end up making things worse. Plus, who does that?

 

[SageBrush]

Plus, who does that?

Your dealership, for one.

I find Nissan and its dealerships offensive. I can well imagine how you feel.

 

[metricus]

Your dealership, for one.

LOL.

 

[smkettner]

May as well pass on the L3 option. I did on my 2011 LEAF and never missed it.

 

[SageBrush]

May as well pass on the L3 option. I did on my 2011 LEAF and never missed it.

It is a glass half full kind of thing. If you think of it as speedy L2 it is a nice option if cheap enough. I find CHAdeMO low value because I cannot rely on it more so than the wimpy DC charging rates. *ALL* of the CHAdeMO stations in my city are inoperative.

 

[mtndrew1]

I don’t mean to be a Debbie downer but I’m of the opinion chasing a remedy to this situation is a fool’s errand.

The car was just clearly not designed for either repeated DCQC or high charge rates at high pack temps. It is trying to protect itself from accelerated degradation which is a known Leaf characteristic.

There’s a reason Nissan set up the software this way and pestering the service department is unlikely to resolve it in a meaningful way.

The gen 2 Leaf is probably designed around the fact that for the absolute majority of customers it will never be driven more than 300 miles in a given day.

 

[smkettner]

+1 the service department said all was normal.... need to accept that LEAF is what it is.