For the past few weeks, our battery has been charging up to 100 per cent during the day and consumption from the grid has been a few pence a day. Suddenly last night we used £2 worth of mains electricity and when I look at the graph I see that at 0200 the battery percentage fell off a cliff. 
](https://) Can anyone please suggest a reason for this?
What BMS version are you on? If 3007 you could be seeing the SoC drop here: https://community.givenergy.cloud/d/713-firmware-3007-has-not-fixed-sudden-soc-drop-to-0-problem/2711
It seems to be 3008. I noticed when looking for that information, that updating the battery firmware would cause it to discharge completely - which is what this looks like. I can't see any setting to allow me to control this, for example to stop it happening in the night and force it to do so during the day while we are generating!
The battery calibrates when the FW is updated. Full discharge to zero followed by full charge to 100%.
I saw this also last night on our system - battery dropped from 20% straight to 0% at around 5am.
We are on battery firmware version 3008
Givenergy please advise
Petergroves81 A full battery discharge would take time i.e. it would export the energy to the grid over an hour or two.
The graph you've shown looks like a bug of some sort - very similar to my graph btw.
Ita the SoC drop...there's a massive thread on it here and GEs months and months of excuses and eventual (partial) fix.
Zebsmattz upgrade to 3012 via the web portal, my inverter page, software tab.
Zakalwe there is more to follow. Inverter firmware too, hopefully not too much longer.
TX200 Thanks very much! I'll wait for a nice sunny day.
I have a similar observation but it drops to zero then straight back up, is this related?
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Simonl The AP appears to suffer from an odd data glitch/missing reading, I've seen it happen on Temp. as well.
Ah ok great thanks
Zakalwe Partial fix is being disingenuous! Its not a 100% fix, that is true, but its a 90% fix at least. And depending on usage patterns its a 100% fix (SOC estimate when battery(s) sit above 40/50% continuously is not working correctly - or perhaps not programmed yet)
anglefire Its not a 100% fix, that is true, but its a 90% fix
So, a partial fix unless there is another definition of "partial" that I am not aware of.