New 40kwh battery on 2018 SL, sudden charge drop at low load

[Jerther]

Dang it's cold. -16c and very windy. Anyway I just did the first checkpoint: discharge the battery to under 10%. Actually I parked the car in my driveway when the car's reported SoC was ---% but leafspy's was 4 kWh, and I let all accessories run full power (~5kW) all the way down to turtle mode then until the car shut down. (It's pretty much exactly as if I'd turn the car on without touching the brake pedal, and the car asks to press the brake pedal and press the ON button. If I do so, the car immediately returns to the same message. Accessories continue to work, but obviously not heating. The car engages in park and neutral, but not in drive.)

Fun fact, the AC turns on when heating and the AC button light is off, but if I turn the AC button light on, then the AC actually turns off. I get it I think, it's for the average users who think AC is for cooling, but it's a bit misleading when you think about it

I did take my eReader with me but the battery was empty. Oh the irony...

So anyway the SoC got down to 0.8%/0.3kWh before the car shut down. Here's the last leafspy screenshot, moments after the car shut down. I noticed the green "All Cells OK" at the bottom that appeared a couple of minutes before. That's good news I guess?

Now it's charging time, and I'll do another full discharge tomorrow.

 

[Jerther]

2nd discharge. It's warming up outside but still cold between -10c and -5c. Went well for my trip to work this morning, down to 62%. Back to home on the highway though, the battery started to collapse from ~40% down to 30 climbing a steep hill. I got scared and decided to leave the highway early and continue at 90km/h on roads. Got other less significant drops and eventually got turtle mode at 13% while driving. Thankfully I could park the car home around noon at about 8%.

I had visitors so it was only about 8 hours later tonight that I went out to drain what was left and, well, there was nothing left. The car was stuck in accessories mode with turtle mode, ---% and --- km. I guess the last 8% just vanished. (EDIT: Nope! Silly me, I just remembered I left it running with the heater full power. So it's fine. It just finished draining the battery while I was inside the house.) Obviously I only started the charge at that point.

I had my ereader fully charged for nothing.

Here's the obligatory leafspy shot just before I connected the EVSE:



Also, the L2 charge count increased by two points? I swear I charged it only once! There was a timer for climate control that triggered this morning while the charge was over and the evse was still connected, and it drew power from the EVSE. Could that be it?

I'll do the last cycle tomorrow.

 

[Jerther]

Last cycle today. Outside temperature was warm-ish, between 5c and 10c. The car did 162km which is WAY longer than that ridiculous 97 km from yesterday. No sudden drop whatsoever. And I pushed it real hard in the last 10%: 0-120km/h with the pedal to the metal, multiple times; it just kept going without any power loss. Heck, I felt so lucky I tried it at like 3%, and it held. Not even turtle mode. At that point leafspy reported battery temperatures around 30c.

So I parked it home at ---% again, about 4kWh remaining, then started all accessories, full power. It took a while to get into turtle mode, then it shut down shortly after at 0.8 kWh remaining. I immediately plugged the EVSE.

I got to read the ereader for a while this time. It started raining at some point so I closed the windows. Man the heating system on this car does a very good job!

So here's the last leafspy shot.



Level 2 charge count has increased by 1. Good

So the 3 discharge cycles the dealer asked I do are done. Next step is to bring the car to the dealer again, but I doubt I'll do that next week as the forecast is quite warm and there's no way they'll replicate a charge drop if I couldn't today. Winter isn't over yet, so I'll wait for a colder day

To be continued...

 

[Jerther]

Here's an update.

After a week or so of really warm weather, we're into another cold snap. I experienced a few charge drops in the past week, and the cold snap is just in time for the Nissan dealer to do another test drive. This time, I had to bring the car between 30 and 40% charge. It stayed outside at the dealer for a whole day, and the next day (today) they did the test drive at about -15C. They recorded a charge drop, sent the data to Nissan and in a matter of hours I got the answer: they will replace the battery.

So it'll be battery #3 for me in 10 months of ownership. Nice.

In the mean time I'm eying a 2022 SL Plus, but apparently my 2018 SL had a CARFax on it, which I knew but didn't know for how much, and apparently the numbers for it were published recently and I learned it was for 19k$!!! So the dealer gives me only 10k for it... I paid 23k+tx 10 months ago for the d*mn thing... Never buy a car with a carfax without knowing the amounts...

 

[nlspace]

Wow Average cell volts < 2.7 !? That sure seems low.

Seems like the 12V battery needs to be charged or tested/replaced?

 

[Drew21]

What do you mean by "my 2018 SL had a CARFax on it, which I knew but didn't know for how much..."? What "numbers... were published recently..." and how does that affect the value of the car?

I thought CarFax was a repository for vehicle history (maintenance, accidents, # of owners, etc). Just curious what you're referring to. Maybe I haven't paid enough attention to the CarFax commercials.

 

[Jerther]

Sorry I meant there was an entry on Carfax for my car, but the amount of the insurance claim in $ was not shown until recently. It affected the value because a 19k$ insurance claim on a car is bad omen for some reason. Dealers (here at least) don't even look at the car. They just extrapolate a value based on statistics or something.

 

[Jerther]

Seems like the 12V battery needs to be charged or tested/replaced?

11.3v is because accessories were on. I checked the battery later with the car off and it measured somewhere around 12.3.

 

[nlspace]

I checked the battery later with the car off and it measured somewhere around 12.3.

Oh okay, that's like at 50% state of charge. When fully charged it will likely be higher.

For long service life it should be kept fully charged at all times, otherwise it loses capacity due to sulfation damage.

 

[Jerther]

Oh okay, that's like at 50% state of charge. When fully charged it will likely be higher.

For long service life it should be kept fully charged at all times, otherwise it loses capacity due to sulfation damage.

Interesting. Can you link to a reference chart?

 

[nlspace]

from Battery University, BU-903