Sunsynk charging discrepancies.

[NoraBatty]

2 nights ago, the battery was at 48% SOC (20.59kw) before charging started at 00:30, and managed to charge to 99% by 05:10, and 100% by 05:20.
Charging rate was rrelatively stable the entire period at roughly 5.5kw/h for 5 hrs.

Last night though,
Battery was at 32% SOC (13.73kw) before charging started at 00:30, and we got to 99% SOC by 04:50 at the exact same charging rate of 5.5kw. The inverter then dropped off and we never got to 100% by 05:30 when cheap rate ended

How is it possible to use 27.5kw over the period to charge the battery on one night, from 48% to 100%

Yet also possible to use 27.5kw last night and charge from 32% to 99%

There is a 7.5kw ish discrepancy here in battery SOC, despite using the same energy to charge over the period.

Anyone got any ideas?!

[NoraBatty]

So you do t think im totally off my rocker
Past 3 days energy ive tried to align the selector bar in sunsynk to show SOC before charging.

The 2nd,






The 3rd








And last nights

[Richard77]

Have you accounted for LGD?

[NoraBatty]

Have you accounted for LGD?

LGD?!
Losses i presume.

The pack is balanced, its less than 1 year old, i cant imagine why a 7.5kw discrepancy would arise unless sunsynk app is wildly inaccurate.
Checked actual battery bms's this morning and they are sat at 99% as the app suggests and balanced to within 0.002v.
Obviously didnt see their charge last night.

[Richard77]

Was it a full moon one night? Clear sky?

Lunar Generation Discrepancies

Sorry... Couldn't resist!

[NoraBatty]

Oh i get you

Definately no moonlight solar.
Would make more sense though!

[Richard77]

Any appliances or EV plugged in one night to use the 7.5kw difference?

There is a spike in the usage on one of the nights isn't there?

[NoraBatty]

Yes the spike was the heatpump for hot water kicking on.
The inverter only allows 8kw ish passthrough currently so is reducing charging above that, which you can see in the charging dent that corresponds with the spike.

Other than that as you can see, charging has been roughly the same level for the 5hr period each night.
No EV to charge.
And the import figures do not reflect 7.5kw difference.
Its really quite odd.

If it was 2kw ish id chalk it up to discrepancies.
7.5kw is 17% of the total battery.

I have an extra battery to add to the total yet, waiting on a replacement fueseholder.

[nowty]

For the SOC to be accurate the inverter will need to count amp hours and not all do, if its just relying on voltage it will not be accurate and I would not worry.

[NoraBatty]

Thanks Nowty.