AIO useable capacity query

[Borders_BESS.PV]

Morning,

Have had a look through quite a number of previous posts, and although many mention it, can’t find one that actually answers this specifically -

System is advertised as having a full 13.5kWh discharge available, but in practice only 12.96kWh is available for discharge as the system reserves 4%.

I could understand this if it was only a 13.5kWh battery, but as I understand it from what’s reported in HomeAssistant, it’s actually a 16.5kWh system, which allows for a ~19% margin to avoid extreme states of charge either end damaging the cells. Much like the 9.5kWh system that is advertised as having 100% discharge - it’s 100% discharge of the available capacity, the 9.5 system is also bigger, just the full capacity is hidden from the user.

So does anyone know why the additional 4% export restriction is applied?

[Bob_Bobbings]

Hey,
I was fortunate to grab a screenshot of one of the 4 cells before the engineer put them in. I’m also very confused by the AIO 13.5 claims.

I assumed the cells were over spec’d for the 100% DOD claim however as you mentioned from the 4% minimum reserve this doesn’t seem to be the case.

If i was to make an educated guess. It would be over spec’d so that any cell degradation happens during the 12 year warranty it has the additional capacity to fall back on.

However the individual cells do actually say 85% DOD. Which is interesting.

I believe the over spec’d cells will explain why you are seeing 16kwh~ in homeassist though.

Thanks
Bob