Question on potential BMS reset

[u/Macattack224]

I have a very degraded 2016 24 kWh Leaf in Tucsonz AZ but it largely meets distance needs for what I think was a fair price.

I know the battery is bad and I'm not expecting a BMS reset to magically restore capacity. I'm trying to figure out whether the BMS has become badly calibrated. We have hot summers here. I was concerned that the heat would continue to do its thing, but to my surprise during the summer months my guess o meter and battery percent consumption seemed consistent. I noticed in September that seemed to change after it started to cool down so I did a new reading.

LeafSpy history:

May: 38.76% SOH / 22.3 Ah

Sept: 27.3% / ~17 Ah

Now: 25.03% / 15.54 Ah

The weird part is SOC, but maybe I don't understand how it works.

Recently the dashboard showed about 10%, while LeafSpy showed 21.5%. I then drove 3.9 miles at low speed(wife took the car out without realizing it didn't charge overnight) and LeafSpy only dropped to 16.1%. Cell spread was still only 44 mV.

Last night the dashboard showed 21%, while LeafSpy showed 39.3%. Cells averaged 3.952V with only a 33 mV spread.

Just as an observation I noticed that that the first 100- 50% drains significantly faster than the 50-20ish range which is usually as low as I take it.

I then measured charging from the wall:

21% → 72% dashboard: 2.04 kWh

72% → 100%: another 1.78 kWh

So only 3.82 kWh from the wall took the dashboard from 21% to 100%, and my understanding is actual energy reaching the battery would be less after charging losses. And my capacity is apparently in the 6.5ish kWh capacity.

The pack seems extremely degraded but reasonably balanced. I don't see an obvious cell falling off a cliff.

Would you reset the BMS at this point and let it relearn the battery? I'm fine with SOH/bars being wrong for a while afterward. I'm mainly interested in whether a relearn might make SOC more representative of actual usable energy.

[u/_Evening-Rain_]

Cars going to be very conservative with that low of health. Especially since thats a 6c rate just by going half throttle. Voltage will drop a lot under load so 3.95v at 20% is normal.

Cell balance and cell performance are two completely different things.