The 40KWH Battery Topic

[LeftieBiker]

I just moved several posts here from a duplicate topic.

[danrjones]

I'm approaching my next 3 month "update". Current stats are:

SOH: 90.05
AMPHr: 103.95
Hx: 104.00

Per my previous posts, my Hx continue to decline. It peaked at 109.17 in June.
And (likely) due to the temp now being cool, the daily adjustment have basically stopped.
I have been at 90.05 SOH since early November.

[DougWantsALeaf]

Dan
How many miles total and since last update? Many dc charges?

[DaveinOlyWA]

I'm approaching my next 3 month "update". Current stats are:

SOH: 90.05
AMPHr: 103.95
Hx: 104.00

Per my previous posts, my Hx continue to decline. It peaked at 109.17 in June.
And (likely) due to the temp now being cool, the daily adjustment have basically stopped.
I have been at 90.05 SOH since early November.

I am tracking the relationship of Hx to rate of degradation. I hadn't noticed the temperature relationship. I got mine in November so could be the "new pack" factor but my Hx rose thru out the entire Winter. In Summer it fluctuated a bit seemingly rising on DC charge sessions more often than not. It has been on the decline for two months now and I am expecting a zero adjustment or maybe even a small bump up...

[danrjones]

Dan
How many miles total and since last update? Many dc charges?

I did two very small quick chargers to test a new fast charger in Inyokern but really they aren't much other than adding to the QC total.

Leafspy shows just over 7830 miles and 9 QC and 380 L1/L2s.
I never put a lot of miles on it, its an around town vehicle.

As to temp relationship, I personally believe the "daily" SOH adjustments are related to temperature. During our summer I will see 0.01 every day chipped away, sometimes 0.02. During the winter it all but stops. Not absolute proof of a relationship but it seems likely to me.
Maybe some form of automated SOH adjustment based on temp, and then the 3 month adjustment fixes that daily estimated range loss by either taking or giving SOH back. Remember, this is just a guess.

[LeftieBiker]

As to temp relationship, I personally believe the "daily" SOH adjustments are related to temperature. During our summer I will see 0.01 every day chipped away, sometimes 0.02. During the winter it all but stops. Not absolute proof of a relationship but it seems likely to me.

The Gen I Leaf does the same thing - it shuts down battery health readings in Winter. I suspect that it's because the BMS can't accurately report this information when the pack is cold.

[DaveinOlyWA]

Dan
How many miles total and since last update? Many dc charges?

I did two very small quick chargers to test a new fast charger in Inyokern but really they aren't much other than adding to the QC total.

Leafspy shows just over 7830 miles and 9 QC and 380 L1/L2s.
I never put a lot of miles on it, its an around town vehicle.

As to temp relationship, I personally believe the "daily" SOH adjustments are related to temperature. During our summer I will see 0.01 every day chipped away, sometimes 0.02. During the winter it all but stops. Not absolute proof of a relationship but it seems likely to me.
Maybe some form of automated SOH adjustment based on temp, and then the 3 month adjustment fixes that daily estimated range loss by either taking or giving SOH back. Remember, this is just a guess.

Agreed with "SOH" and temperature and also the reason I am tracking Hx. First Winter, SOH slows to reduction every 3-4 days but Hx is high; over 120. Jan adjustment is big, 1.5%. Then right towards end of quarter before April adjustment, Hx starts to fall and SOH reduction changes to every 4-8 days, April adjustment; just under 1% drop. Hx continues slow decline to just under 117 and July adjustment goes up 1.12%

Now daily adjustments are holding steady anon my work week (4 days) short commute 27 miles RT verses longer day off travel when I would see a drop almost always .02% although I had a handful of times I traveled over 80 miles (under 100) with no change and this pattern runs until I trade up in Nov with Oct adjustment of zero. In fact, my estimated Oct adjustment window saw a streak of 10 days with no change.

Strangely, the last 3 weeks before trading, my Hx starts wandering up again. Was in high 114's and gets to low 117's by trade date but daily changes holding at slightly longer intervals (5-8 days) than first winter.

So I feel that Hx is telling us something but still unsure of what it is.

[danrjones]

The only evidence I have in regards to HX, and its very anecdotal, is that it relates to SOC

When I charged to higher SOC hx seemed to start going up. I used to routinely charge to 80 to 85% plus occasionally 100%, but early last summer changed that to about 70% with no 100% charges. Since then my hx has been going down.

[danrjones]

Per my last, the more I look through my data, the more HX seems connected to my SOC.

As an example, over the weekend my SOC was sitting right at 70% Saturday through this morning. No Change in HX.

Looking through data, my HX seems to go up whenever i have charged above about 78%. It REALLY went up anytime I charged above 90% or to 100%. Letting the battery sit at high SOC seems to be the worst, and HX would continue to rise for some time after that event.

Letting your car sit at SOC between about 40% and 70% seems to be the ticket for HX dropping.

Anecdotal evidence but it is what I see looking through my data.
My last big rise in HX was Feb to April of this year, where my HX went from 106 to over 109.
What was i doing during this time? I was hiking close to home, which meant I could use my Leaf.
But I was having to charge it to 90 to 100% to make the trips.
Come may it gets too hot, and I was hiking further away, using my other vehicles.
At that point I started only charging to ~70% for work and around town driving.
But I don't charge every night, I let it drop to around 30% (about every 3-4 days).
So the battery gets a good amount of time right in the middle of the pack for SOC.

[DougWantsALeaf]

Here are my Leaf stats for my 2 Leafs. Both 62s, but I can't figure the Hx.

https://docs.google.com/spreadsheets/d/ ... p=drivesdk