I am still not really happy, but I have not worked it all out.
We know that a lower temp means less capacity. You can have the same batt at 15% lower AH capacity at freezing than at 77F. The graph also shows that a full battery will have higher SG at lower temps. We are also taking higher SG to mean more capacity because of less sulfation.
I think the graph showing "100% SOC" is not meaning the same as 230AH for a GC15, Eg. All the graph says is the battery is full. "Percentage of what?" again.
Using the table, full batt: 80F = 1.265 and 30F =1.285 diff of 0.02 for (typical) 15% lower capacity due to temp.
Can 0.04 rise in SG from lower sulfation also be worth 15% in AH capacity?
(We are assuming also K's batts have the factory "moderate" SG level and not the lower "high ambient" SG level of acidity. If Mex is watching, can he say if Mexican level SG batts have a marking to indicate that is their factory SG level? ) K could then check his for that marking if any.
IMO we need actual capacity tests for AH to go with K's results for a complete view of what he got. He certainly got higher SG for "full" by doing several Es. But how many more AH in capacity did he get after doing the first couple of Es? I don't know.
"Capacity" has become weirder now we have guys using watt-hours instead of AH. K used to be suspicious of doing 10 hrs down to 50% and then doubling the AH down for the 20 hrs worth. He didn't believe the SG vs capacity was linear all the way down. Turns out he was right for watt-hours.
LFP "capacity" involves some fudging to make their 50% a compromise between the AH and the watt-hour half way down point. Also LFPs don't even do it at the 20 hr rate. They just draw say 100 amps for an hour and call that "100AH". Can't do that with wet 6s.
The table K has posted is one version of the many SOC vs OCV and SG tables out there. My GC15s act more like the Trojan table for OCV but a tad higher for SG than the Trojan table's. Not sure if that matters for what K was doing there.
Table 7 scroll way down.
https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
