Secondary battery killed by cold weather

I have an AC coupled system with a nwer 9.5kWh battery as the primary and an older 8.5kWh as the secondary.(both on BMS3017)
Normally they charge overnight on Octopus Intelligent Go but as they are exteranlly fitted a few day ago they got too cold before the charge window and were stuck between 0-4%.
I then realised there was a new Winter Mode and switched that on. This slowly revived the 9.5 which then charged up but the 8.2 was still stuck on 0% (about 47V)
Whilst trying to contact GivEnergy the system has been trying to trickle charge (20-30W) but no power was gettting to the secondary which was slowly dropping voltage as it flashed its LEDs.
Today the secondary is completely off and now showing 0V. That at least means my primary is back working as the system is no longer trying to revive the secondary.
Any ideas how to revive the secondary or do I just have to wait until GivEnergy support bother to respond?

MAGOR it'll be because the voltages of the two packs are now wildly different.
You can try a calibration from the portal - that should take your running pack down to 45-46V and you'll need to time this well but try and switch the other pack back on when it gets to that kind of sub 50V voltage. They should then both combine and charge back up hopefully.

Thanks I'll try that

How do you "calibration from the portal"? i am unable to find that option.

ianmart portal.givenergy.com/myinverter

Then click the little cog icon I think.

Then it's in there. Remote control page it's called.

TX200 There is restart inverter there but I don't get a calibration option.

GrahamShaul it might be that you have to ask the installer or givenegy to make the calibration option available to you, and then it'll allow you to schedule.

Re-Calibrated.
It only did the Primary as the secondary is now properly off at 0V and I can't switch it on. I think it would have worked if I had caught it in that 47V-35V phase as it drained. If only support had responded in time.
BMS must still be alive as it is still reporting temperature on that battery.

MAGOR

You will need the help from GE a bit pants but hopefully they will sort it for you eventually.

Let us know how it goes...

Support eventually responded and brought my sleeping battery out of hibernation and back to 45V. Then I was able to discharge the working one and recalibrate.
Back to two working batteries now.