Battery capacity degradation

[Trukinbear]

Hi, I'm experiencing a large disagreement between the SOC as indicated by my 2-250 Classics & Whizbang Jr - and the SMA SI6048 they are networked to. Classics say 100%, but the SI6048 might say 65% - 85%. When the Classics say 85% the SI6048 will be in the 40's and cranking up the generator.

I appear to have diminished battery capacity, and the SI6048 shows a SOH ~75%. If I tell the Classics that my battery is 75% of what it's nominal rating - will this help fix my problem, make it worse, or cause a new problem?

[ClassicCrazy]

I don't really understand your system but I would trust the Classic SOC as long as the shunt for it is wired correctly ( one negative connection to battery on one side, and all other negatives on other side).
Does your SMA  use the same shunt or different one ?
I would have no idea how the SMA is programmed to count and calculate SOC - the Classic takes temperature and efficiency into account for calculating the SOC.
Also no idea what kind of batteries you are using . ( sorry  didn't see your signature with system specs when I was replying . Are you batteries lead acid or lithium ?)
The Classic will go to 100% Soc when it goes to float . No idea when your SMA resets Soc.
You can adjust the capacity setting , and or the efficiency settings for the Classic SOC readings. 
But first you would want to know which SOC is correct.  You have to look at Soc numbers as an estimate more than an exact number.
I know that when I got my lithium batteries the bms in them calculates soc and it can get way off if not charged all the way to top every day , and then have some days of partial recharge. The Classic turned out to be very accurate for soc compared to what the lithium bms soc reported.
Larry

[boB]

The Sunny Island's SOC system has known issues where it messes up the way it charges.

This is what I have heard from MANY people in the US. Not sure how accurate or inaccurate the reported SOC% is but evidently it can be wrong enough to keep the SI from charging the batteries properly so I don't think I trust it very much.

I would trust the Classic over the S.I. because of this S.I. issue that I hear about.

BTW, the Classic's modification of lead acid battery capacity from battery temperature was also in the S.I.

boB