Patience or Push the Issue (New Cells/New Pack)?

[mn4az]

Appreciate the analysis and it fits with my thinking, which admittedly was more piecing things together than rooted in data. The theory of not having access to 20% of the pack (my speculation is the BMS is doing what it can to protect the pack) because of the low voltage/all up battery degradation makes sense. Which also fits the reasoning of getting 37-ish miles on a full charge.

At this point is sure seems as if...

Low cell voltage + Pack Degradation + Power Draw (speed, elevation, heating cabin and temps) = "Motor Power is Limited" (MPL) where the BMS doing what it can to protect the pack by making ~20% of it not accessible to the driver. Thus, turning it into a glorified golf cart at this winter. :-(

My college age daughter is driving the car about 15 miles round trip to her engineering internship, and we are doing some experiments. The charge timer and pre-heat timer are set for 730a M-F and the car sits at her internship unplugged for 8-9 hours and isn't driven during that time.

Yesterday she did not get the "Motor Power is Limited" on the way to her internship (expected) but, after it being cold soaked (it was around 20F yesterday) she got on a section of road that is 55MPH and climbs approximately 100 feet over about a half mile. This small climb starts at about mile 5 of her 7.5-mile commute home and the MPL appeared. It stayed that way for the rest of her commute home. I expected this to happen, but she didn't. She figured that with a 70-80% SOC it would be fine.

Today the temperature is hovering around 35F, and we'll see if the MPL appears or not. I'll report back the results.

Of interest to me is why the owner of the Leaf in the below thread had a DTC appear and we haven't yet. I speculate the voltage difference he had was/is higher than mine, thus leading to the DTC event.

https://mynissanleaf.com/viewtopic.php?p=627932#p627932

 

[SageBrush]

A cold soaked battery is going to bring out the worst in the pack for sure.
No chance of finding some shore power while at work -- even L1 ?

 

[mn4az]

Yeah.. highly aware of that. There's not a plug she can use. Her thought process is that if the car fails on the way home - so be it. She's got AAA, I'm nearby to come get her and we (fingers crossed) get on the wait list for a new pack.

Also... a quick thought on this.

Addendum
Let's calculate Wh/mile again, using what is surmised:
A new 30 kWh pack has about 28 kWh usable
Your SOH of 0.68 implies a usable of 19 kWh
The weak cell cuts off the bottom 20%, so 15.2 kWh is usable
You arrived home with 1.9 kWh remaining, so 13.3 kWh was used to travel 37 miles
13,300Wh / 37 miles = 360 Wh mile.

Hmmm. That is more believable, particularly if you were sitting idle at stoplights since you were still drawing the better part of 3 kW for cabin conditioning. If you can, try low speed highway driving for your commute.

I arrived home with, according to LeafSpy, .9 kWh remaining.

14.3 kWh used to travel 37 miles
14,300Wh / 37 miles = 386 Wh/mile - which isn't all that off from what my '15 Tesla Model S 70D would get.

 

[mn4az]

Yesterday she did not get the "Motor Power is Limited" on the way to her internship (expected) but, after it being cold soaked (it was around 20F yesterday) she got on a section of road that is 55MPH and climbs approximately 100 feet over about a half mile. This small climb starts at about mile 5 of her 7.5-mile commute home and the MPL appeared. It stayed that way for the rest of her commute home. I expected this to happen, but she didn't. She figured that with a 70-80% SOC it would be fine.

Today the temperature is hovering around 35F, and we'll see if the MPL appears or not. I'll report back the results.

No MPL event today. Temps were around 37F when she drove home. I added 5 more pictures to the OneDrive album. Should be the last 5 in the series that starts with the car's dash displaying a 69% SOC.

https://1drv.ms/u/s!AmMHBcyzLWAx8K89Z3ZoHYghn5xg-Q

Barring a DTC happening we'll have to just limp along through winter. Not going to have the dealership take a look at those cells without a DTC event for fear they replace the cells and put at risk the bigger prize - a full battery pack replacement this summer.

 

[Dooglas]

Here's my advice based on the fact that I just went through a cell/module replacement (not under warranty) in my 40 kWh pack.
I would wait to trigger the 8CB replacement pack warranty. You will get a 40 kWh pack (much better lifespan than the 30 kWh pack) and there are simply no "replacement" modules available in Nissan's system (I bought mine on eBay); that's not to say you will get a new pack quickly either, but probably faster than a cell replacement--not to mention your weak cells span 2 different modules (I only had to source 1 module).

My understanding is that Nissan is likely to propose a buyback for a warranty claim on a 24 kwh or 30 kwh battery pack. Due to the shortage of replacement packs (and no 30 kwh packs), Nissan appears to be saving the 40 kwh packs for newer vehicle warranties and new production. A buyback is probably a cost effective choice for Nissan in the case of an older vehicle.