Sunsynk charging discrepancies.

[robl]

Took me ages to get our sunsynk soc to mean anything about right. We’ve a fogstar batt, with 305Ah eve cells, and the sunsynk talks ok to the fogstar battery bms, and is on the Libms battery setting. I’m pretty confident even though the fogstar calculates soc itself and the sunsynk is connected to it, the sunsynk uses its own Coulomb counting to calc SOC, and flicks to 0% or 100% when it’s at the voltage end stops. To get a plot of SOC charging from 0% to 100% to not have jumps in it at one of the ends I ended up through trial and error telling the sunsynk the battery size was 425Ah - this was a year ago, and it seems ok with that. No idea how that is so wrong but works.

[NoraBatty]

Took me ages to get our sunsynk soc to mean anything about right. We’ve a fogstar batt, with 305Ah eve cells, and the sunsynk talks ok to the fogstar battery bms, and is on the Libms battery setting. I’m pretty confident even though the fogstar calculates soc itself and the sunsynk is connected to it, the sunsynk uses its own Coulomb counting to calc SOC, and flicks to 0% or 100% when it’s at the voltage end stops. To get a plot of SOC charging from 0% to 100% to not have jumps in it at one of the ends I ended up through trial and error telling the sunsynk the battery size was 425Ah - this was a year ago, and it seems ok with that. No idea how that is so wrong but works.

Thanks for that. I think once i get my finger out and sort networking and HA integration, i will have access to each cell data across every bank but for now just using the app made no sense.

Checked the voltages from the app after Nowty said, seems there was 0.01V difference between thr days so fairly similar and im just not seeing accurate readings as you say.
Shame.
Yet another reason why i wish id have stuck to the original plan and gone victron now.
I am happy enough with the sunsynk but you never know the ins and out until you dive in.
I may swap it all over one day, but for now its working find and im sure once HA is integrated i will be happier.