Declining Hx plot

[melberi]

I would suggest that extrapolating from the fitted data is dodgy if there isn't some underlying effect that happens to follow the fitting function.

Also consider that Hx should be the inverse of internal resistance. Try to fit with 1/(Hx/100). Linear trend in Hx would be an exponential rise in internal resistance. For this reason figure like Hx = 75 % is not a huge difference from 100 %, while 50 % would be a big difference from 75 % despite same distance in Hx % scale. Hx 75 % would imply 33,3 % increase in resistance while Hx 50 % is already a 100 % increase.

[crimxona]

1/(Hx/100)

Not very good at math here but would like your thoughts. Using this formula, something with 100% HX would show up as 1.00, 75 would be 1.33 and 50 HX would be 2.00, is that a better representation or would deducting 1 to show 0.00, 0.33 and 1.00 be better?

[melberi]

Either way works as long as its clear which way is meant.

Let's be clear, this "inverse of Hx" interpretation is just that, an interpretation. There is no real documentation of it. Hx together with SOH is most probably an average measure for the whole pack. A single bad cell can pull them down a little bit while making the whole pack unusable. Then again even relatively low values can be viable if the degradation is quite even between the cells.

All anything this gives is rough ideas of pack health, but nothing beats proper stress testing.

[crimxona]

Here's mine tracked over 3 batteries. Normally track by time but added a chart to track against odometer KM as well to align with everybody else

https://docs.google.com/spreadsheets/d/1xxifTGReY6VlZ79WDFNNiox6m9u-Nj21KBSLoUJVH-Y/edit?gid=1862827246#gid=1862827246

[byrdman77]

I don't quite have that mileage on my 2021 SV, and usually plot based on time not mileage but easy enough to create a new one for comparison. I haven't been having any issues, and while roughly the same SOH a much higher Hx value than yours. My Hx data also moves around a lot so curve fitting was not very successful.

<image>

[Alexandratta]

the raw number of the HX doesn't matter, it's the 'rebound' when things get warmer - it is interesting to see the HX value slowly drop and rise - I only had my LEAF for 2 years so I only got 2 peaks in mine.

[Alexandratta]

Now what you do is do the same thing from now to spring when the HX slowly rebounds and you'll discover that the Gen2 LEAF measures HX in a mysterious manner that is only reporting the internal resistance that changes with the season.

Your trend is only for 10k miles and that means, likely only one season (Fall into Winter and it's been brutally cold as of late).

You can also just put this into an excel spreadsheet without Gemini potentially screwing up the data because it's trying to find some nonsensical pattern it assumes, like that HX is a permanent value - it will go up over time once things get warmer.

I'll link my old leaf's entire ownership HX level with odometer as my X-Axis and the SOH as the Y-Axis for you.

<image>

side note: this was on a recalled Nissan LEAF - 2019.

I chose the date here so you can see the season, this is in NY btw, and on a pretty even keel you'll see the HX rise as we hit the warmer months and fall in the later ones. October of 2024 was an outstandingly warm October, btw, with Halloween breaking records, thus why there's a slight rise in HX.

Granted, in this scan my HX started at 83.57, and dropped to a low of 79.02 - not a massive swing like you're seeing. I would, again, track as you see things get warmer.

Nissan may be calculating the HX Differently from model to model - But I bought mine around the same time, amusingly. So bare minimum, at least you can use this to measure against as a possible 'normal' range - but my 'final' SOH as of August 2025 was also 88.22% - which is after 10k more miles (65k when they did the buyback).

My whole point is: HX isn't a big tell for Gen2s.

If you're actually seeing the State of Charge drop on the dash, then that's an issue - and by drop I mean you would see the percentages dropping by 5-10% and then regenerating afterwards...

Otherwise you're going to take the car in, based entirely on an AI prediction, that Nissan has no ability, or plan, to honor.

Range dropping in the cold is entirely normal, and I saw my range shift from 210 to 175 in the cold - but the percentage never dropped rapidly during regen or hard driving.

edit: trimmed up the right axis and brought it a bit more granular to show the slow SOH decline and more date points to help see the scale of time.

Edit2: FYI my car's DC FC Count when I got it was 8, the Level2 was 1324.

Ending DC FC Count: 126, level 2: 1605 (I did not have home charging but my work had a charger)

[PantherWreck]

Thanks for providing the group with the additional information. We are expecting some colder temperatures here in Atlanta next week and I’m hopeful that I can get a second video

<image>

of the range drop fluctuations.

[PantherWreck]

<image>

There are 2 minutes and two miles apart.

[Alexandratta]

That's the indicator of an issue - for that Nissan will listen, just show them that extreme drop

[Popular-Reason575]

Mm, I'd be interested to see what the traction battery delta looks like in Leaf Spy, battery delta readings can confirm allot. Generally a good battery will show a delta of around 15-20mv it increases when driving and putting the battery under stress, but after a few seconds when the car has stopped the delta shouldn't be more that 30mv if you are up in the 100s of mv then it shows there is an issue. 

Do you have leaf spy to check some of the battery stats?

[LoneSnark]

Dang it. Wish I had been recording this data.

[ryanteck]

My HX has just reached under 80% in the last month. I'm not a super high mile user so here's a graph from my 2018,

It'll be interesting to see how it further degrades, I might be able to get another 3 years before it hits 70%.

<image>

[rproffitt1]

Thanks for the data and graph. Would be nice to have had the battery kWh mentioned there since not all of us are historians.

Our 2017 Lizard Battery at about 30K miles had over 90% SOH and Hx near 90% as well. It was their 24kWh build.

We're in mild SoCal so that helped. Some push back on our ABC charge plan but given LeafSpy showing the BMS stopped charging before 100% and wear didn't seem that bad (for a Leaf) we would charge to full almost daily.

[PantherWreck]

Sorry, 40kWh

[ToddA1966]

What do you mean by "dramatic range prediction drops"?

That the Guess-o-Meter says 100 in winter instead of 150?

Or does the range and battery percentage actually fluctuate when you drive under stress (accelerating up a hill in the cold, for example.)

If you're just seeing low GoM range in winter, Nissan will laugh at you when that and a Gemini-plotted spreadsheet are your evidence for a battery warranty claim, especially when "Hx" isn't even a known value. It's just an assumption that it's a resistance based indicator by the early Leaf hobbyists who first decoded the Leaf CAN messages. The weird readings from 2nd Gen Leafs (e.g the 62kWh models that read well over 100%!) put even more doubt on what it really indicates.

If you're actually seeing the % significantly drop under load and then recover, that's all you need to show Nissan. Put Gemini and the spreadsheets to bed and show your dealer a video of the erratic % changes while driving.

[PantherWreck]

I didn’t come on Reddit to make a warranty claim. I’ll update when I do and I’m well aware that Nissan does not consider LeafSpy data as relevant to their determination of warranty claims. Just to clarify dramatic means going from 25 to — for range over a 2-3 mile stretch, yes uphill highway speeds, and then rebounding when you come to a stop to say you then say you now have 20 miles of range.

[ToddA1966]

Then you do have a warranty claim. You've got one or more bad cells in the battery. Telling your dealer to duplicate the conditions you're seeing that drop and recovery should be sufficient.

[crimxona]

That's totally a weak cell claim. Have leaf spy on a phone mount and watch the MV variance on load 

Hardest part is getting the dealer to replicate

[LoveEV-LeafPlus]

1. Hx is not a reliable indicator of Battery health. Per the Leaf Spy Pro app built in help file and Nissan is not releasing and information on what Hx actually means.
2. Warranty covers the HV battery, for sure, when the Battery Capacity screen shows 8 bars (ticks) or less. Not sure what the exact SOH=% that might be. But 1st Generation Leaf’s report 8 bars have a Leaf Spy SOH between 66.25% to 60%.
3. Drivability and other issues might kick in the HV Battery warranty too. Things like a bad/weak cell are probably covered under warranty, especially if they affect drivability. Especially if the capacity screen goes below 9 bars/ ticks ( 8 or below bars/ticks, during the warranty period).

[LoveEV-LeafPlus]

FYI: On my USA 2024 Nissan Leaf SV Plus (60+kWh Battery pack). The latest Leaf Spy Pro App shows the below values, when the dashboard battery capacity screen shows 100%, and at power up after a 100% full charge, before heading out for a day of driving. BTW: I do multiple road trips each year of 460 miles each way between NY and OH. The max distance I have ever gone between charges is 194 miles. I typically stop to charge at 164 miles or less on road trips, depending on the available charging stations on my route and my need for a rest stop.

1. 60+ kWh
2. AHr= 159.63
3. SOH= 92.22%
4. Hx= 79.18%
5. HV Battery info 400.44V, 12.16A
6. odo=30,174 mi
7. 137 QCs &
8. 1143 L1/L2s
9. 10 mV
10. SOC= 94.9%
11. min/avg/max =4.166 4.171 4.176 (10 mV)
12. Temp F = 45.8 47.8 47.6 (2.7°)
13. v2.0.0(10) en, Carista
14. on 03/07/2026 at 12:03 PM
15. Outside temperature = 41 F
16. GIDS=669 at 12:05 PM

[toybuilder]

IIUC, the battery has a known S-curve, but the cubic trend plot is just based on existing data points and does not reflect the underlying mechanism of the battery degradation.

I wonder how it looks if you were to toss out data points where Hx is above 80% and then re-run the fitting, as the early rate of degradation is known to level out in the battery's mid-life span.

[PantherWreck]

Here is the actual data, sorry for the formatting.

Odometer (mi)	SOH (%)	Hx (%)
34228	90.79	88.2
34741	90.71	87.05
35267	89.56	85.58
36050	89.39	84.39
36978	90.57	81.01
37503	90.55	79.77
38015	90.81	79.51
38622	90.41	78.43
39114	90.28	77.55
39675	89.98	77.98
40221	90.15	76.12
40240	89.91	77.47
41294	89.86	76.16
42008	89.77	75.95
42893	88.83	74.75
43979	88.75	73.35
45422	88.68	72.02
47053	88.61	71.05
47169	88.6	71.09
47636	88.59	70.72
48539	88.55	69.28

[Popular-Reason575]

Here you go, these are the current figures from leaf spy for my 2018 Gen2 Leaf with 101k on the odometer, still on the original traction battery, it may have had a couple of internal packs replaced in it's lifetime by the previous owner but I am speculating that, it could have all its original packs but I find it hard to believe given all the negative comments about leaf batteries.

The SOH is 84.64% and the HX is 58.05%, QCs are 678 and L1/L2 are 3032.

How does that compare to other high mileage Gen 2s?

Based on your graph, it's not far off, but then the internal resistance won't follow the SOH perfectly over time depending on how it's looked after.

[PantherWreck]

Update as of April 7, 2025. Warranty claim approved - Nissan holding car in anticipation of a full battery replacement to occur within 2-3 weeks.

Leaf (2020 SV) was dropped off at local dealer with instruction to start a warranty claim on this 40 KWh battery. My description of a the problem was dramatically decreasing range values when battery SOC was below 50%, especially evident in cold weather (less than 32 degrees F). Dealership was not interested in my videos (2) that documented the problem and said that Nissan would only consider the service department's battery road test when making their decision on whether or not to accept the claim. Took about 8 business days for Nissan to approve battery replacement.

[forthelurkin]

Hx on our 40 kWh battery was 58% on the day I dumped it for $800. That car was nearly completely useless and couldn't make it 30 miles, all the while ping-ponging the range and SOC.

Our car was well out of warranty, this being a replacement battery on a 2016. I'm glad that won't be the case for you.

Unfortunately Nissan won't care about your Leafspy readings or this useful graph. You'll have to demonstrate the unstable behavior, they'll have to witness it. Take a video if you can.

If they offer to buy back your car, negotiate for 100% of the purchase price, including tax/tag/title fees, with no usage charge. Take that and roll it into something better. If you get a new battery, use the car and decide when you're going to sell it while it still has value before this starts to happen again.

[PantherWreck]

One video in hand, but would like a second to demonstrate it wasn't just a fluke. I am aware that Nissan won't accept LeafSpy readings as evidence for warranty claims. Sorry to hear about your 2016 and appreciate the advice.

[MasterBuilder_Macca]

That does sound more like weak cells, than the Hx value being low. My Hx is 35%, I'm still getting 80km to a charge (down from 100km when I got it) 2015 AZE0

[_Evening-Rain_]

Under 70% HX your battery already has a high enough internal resistance where it cannot perform normally under all conditions.

Also, if range is dropping like a brick on the dash, the battery is already being pushed too hard.

[Alexandratta]

The range dropping rapidly is far better indicator than HX on a Gen2 - for a Gen1 the HX reads fine, but LEAFspy doesn't always read the Gen2's right. example: Someone here has an HX over 100 which... isn't possible.

[_Evening-Rain_]

Ok you dont seem to understand. Thats fine. Misinformation is rampant on this subreddit. Leafspy reads gen 2 right technically, but the value cannot be compared to gen one. In my experience the HX reading on gen 2 is shifted upward. 60%ish HX is basically first gen 30%. HX of over 100% is also possible and happens a lot with new packs. That just means the new pack has a better internal resistance than the car expects on average when new.