Quarterly BMS Updates on the Gen 2's

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DaveinOlyWA

Well-known member
Joined
Apr 24, 2010
Messages
16,361
Location
Olympia, WA
As most of you know, every 90 days the battery stats go thru a change. The numbers can go up, down or stay the same. This is the ONLY time the numbers can go up. During the time between adjustments, the numbers only stay the same or go down.

Now for anyone who monitored their battery thru LEAF Spy, they were shocked, dismayed, pissed, etc as they watched the numbers plummet the first year or so...Well at least most of us did. But why not all of us? What were some doing that preserved or at least slowed their initial rate of degradation?

Well, its my contention that the BMS is lying. You didn't lose a big chunk of capacity right away...at least not technically. Yes, you did lose the ability to access that extra range but it wasn't thru degradation and I am currently performing an experiment that will lend more credence to the idea that the BMS is building a hidden top end balance based on how we charge and use the car.

The experiment will first go thru a period of low usage. During this time, smart charging will be employed with SOC target of 50% average covering a range of roughly 30-65% SOC. 16.6 mile work commute with 10-40 miles per day on weekends but can vary much more than that (181 miles in fact for a Christmas Party) with ZERO DC charge sessions. Target monthly mileage; 600. The goal here is encouraging a larger top end buffer since the pack is lightly used.

Then I will flip the script and double the weekly commute mileage and 50+ miles per day on weekends and include a handful of "road trips" I will also be practicing a much less predictable pattern of driving. SOC range 5 to 80% but still avoiding full charges as much as possible. DC sessions will happen due to necessity. Target monthly mileage; 1200. The goal is shrinking the hidden reserve because of the BMS's uncertainty of how much range I will need.

Adjustment History
Adjustments take anywhere from 1 to 9 days. Most are 3 days or less including the zero adjustments which...is a day long. The longer the adjustment, the greater the change and the most likely time the top end buffer is being adjusted if not all the time. Before the experiment, the 4 longest adjustments

The first one Jan 2020; 9 days 3% loss
2nd longest at 6 days in April 2021; 2.2% GAIN
3rd and 4th longest July/Oct 2023 where I went from the low 89's to 92% both were 5 days.

But...The Jan 2025 adjustment has just completed at 11 days.

Stay tuned.
 
On the edge of our very comfortable zero gravity Leaf seats.
Yeah, not sure I can sit on this either. Thinking it will have to be a two parter. For reference; Averaged just over 1000 miles a month the previous 4 months before the experiment. Did 743 in Nov, 643 in Dec. Then the adjustment losing
On the edge of our very comfortable zero gravity Leaf seats.
Yeah, not sure I can sit on this either. After averaging over 1000 miles per month the previous 4 months, I did 780 in Nov (198 in one day) 653 in Dec then the adjustment lasting 11 day (previous longest was the very first one at 9 days) losing 4.59 ahr and 2.61% SOH.

I will start in 2 months and flip the switch going back to higher mileage including longer road trips, DC charging, etc. to see how much of my "loss" I can regain.

Another thing; many felt my big losses in year one was due to a lot of DC charging. I haven't had a DC charge since July soooo...
 
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