@robl

I don't know about the new Fogstar unit, but the Seplos installation tells you to charge fully and discharge fully to learn the capacity.

I changed the capacity in the BMS to 280ah, then let the battery charge at 100A using the AGM mode on Sunsynk (with excessive values so Sunsynk itself didn't try to stop the charge/discharge) until  the overprotect warnings are thrown.  Then discharge down at 100A until the warnings at the bottom are hit.  Then change back to Li-BMS, this seems to get a reasonably accurate capacity.

Ok, I can handle that - will set for voltage mode and try.

Regarding the evening charging - how do I combat that?

Under battery settings, Grid Charge is ticked.

There is a further field for 10-90 setting. I set @10%

Any way to disable this?

Can you post some screen shots of how your inverter is set up ? Someone might be able to offer some advice after having checked your settings?

Grid Charge in battery setting is the 1 I suspect.

Note - tried many setting to get it to stop charging this evening.

I don't think I'd buy the Sunsynk again, even tho it was recommended. No solar connected to my unit.

@ggw 

Silly question, is your time set correctly?

I would generally try to diagnose any problems by looking at the inverter itself rather than the app, just on the off chance settings haven't saved correctly.

From quick glance, your "System Mode" settings now look right so not sure why you would have a charge happening in the evening - could you describe more in detail what happened/happens - at what time it happens, SOC etc.  I would try to solve this one first rather than also trying to solve the battery charging upto 93% as that sounds like it could be either your battery settings or inverter settings.

I don't have the Fogstar so can't comment too deeply on that, but I should expect it isn't too different to using a Seplos BMS.  When it charged to 93% did the battery/BMS show any warnings or errors?  Any errors in the inverter log screen?

are you pressing save when you make changes? some of my settings are different to yours ....

Posted by: @ggw

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get it to stop charging this evening.

One possibility that has just occurred to me is that the battery to inverter communication may be unreliable. When the battery is charged from mains what SoC does the inverter think the battery is at? Might it be worth setting BMS_Err_Stop to try and force out a fault under these conditions?

Posted by: @ggw

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I don't think I'd buy the Sunsynk again, even tho it was recommended.

I'm sorry to hear that you are frustrated with the system. I personally found it difficult to understand why the inverter made certain decisions, although the intermittent internet connection combined with the installer setting the Octopus Flux valuation method (which kept on resetting system mode changes) were key factors hindering my understanding.

When we first installed our Sunsynk I initially tried to use Li-bms as the battery state - this was dreadful, resulting in all sorts of weird behaviour when the batt was low or high in charge.  Including repeated charges from the grid, as the low charge state suggested it needed urgent charging.  
Then I swapped to upper and lower voltage limits, the sunsynk figured out the batt Ah rating - it all worked fine on this Lead acid (volts) mode.  I now run with Li (%), and it’s all fine as it understands the batt Ah rating.   

Also I remember when first setting up I didn’t earth the batt box to the sunsynk - the bms data was intermittent like that.  After earthing it’s been fine.

my only issue with the Sunsynk was setting it up to 'co ordinate' with my existing PV and inverter installed under FiT, after i figured it out, it has been 'perfect' - i would still highly recommend a Sunsynk inverter ....

most issues seem to be user error - (which unfortunately reflects on the instructions sometimes ....)

I cant however recommend the app in terms of it actually working and displaying data, distruptions seem to be quite common !!!

SITREP

1. Evening charging seems fixed. Adjusting the shutdown, low battery and restart fixed that. Apparentl

y the inverter will not let the battery go below 11%

2. Still.not charging to 100%. Stopping at 90%. Trending down over time

3. Battery voltage by BMS still 0.3V out of sync

We have 304Ah batts too, but after letting the sunsynk auto detect to the size, it thinks they are vastly different to this.  Our system now works very well; I can charge to 100% or discharge down to 1% without issue, and get the full capacity out of the cells:

Posted by: @ggw

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the inverter will not let the battery go below 11%

I think https://www.sunsynk.org/post/battery-bms-and-restart-shutdown-voltages  might be of interest to you. Effectively the lithium shutdown voltages are controlled by BMS SoC *and* detected voltages. Yes it is very much a hack that you have to set battery type to AGM V in order to set the latter parameters. I'm sure a software engineer at Deye HQ was very proud of themselves for adding another expert friendly feature. This might also explain why @robl no longer has any problems, having lived with the AGM settings for a while.