Cold Weather - BMS worked!

Just thought I would give an update on my outside wall mounted battery. I have been doing a long slow off peak ECO 7 charge on most cold nights, so the battery keeps itself warm. Up to last night our outside temp hasn't dropped below -5'C and this has been enough to keep things ticking over. Last night the temp dropped to -7'C and although the battery temp on the dashboard inverter icon still said +5'C the battery shut down at 04.40 and didn't kick back in until 10.00am this morning. It did it all by itself, so I guess the BMS low temp cutoff to protect the battery does work.

What was a bit weird was that usually the house base load bobbles about a bit over night, but it stayed a completely straight ( though slightly inclined line line). The base load won't disappear, so I must have been drawing power from somewhere - I just can't figure out if it was from the grid or the battery.

I didn't put on any serious load until the system was up and running again. But what would have happened if I'd done that, or tried to export to the grid while the system had shut down -any ideas appreciated as we're dropping below -5 again tonight.

The straight line you describe would be an offline inverter, then draws a line between the last point and the 1st when back on. Leaving a straight line between the 2.

You can discharge a cold battery down to -10C happily. Charging is the issue

Do you have any kind of cover over it? Mine is external, temp dropped to -8c the last 3 nights running and my system has stayed online. I built this around it when I had mine installed July 2021. Though I have extended it recently to take a second battery.

I have had to wrap up my battery in a bubble wrap foil with an additional blanket over the top of that and my system is in the garage. This was after seeing temperatures close to zero. Don't understand why a system that is supposedly designed to be fitted outside is not fitted with heaters.

TheDragon (GivEnergy) Thanks - that seems to be what it looks like. If I move the cursor over the graph there are no readings between going off and switching back on.

I actually made a mistake and the inverter icon battery temp was 8'c not 5'C when it cut off - so obviously looking at this setting to determine battery temp is pretty meaningless as it has run fine at that temp on all the other cold nights! When you say it was "the inverter" cutting out do you mean the AC3.0 inverter or is there another inverter in the battery? According to the inverter icon "inverter data" this was running at 18'C.

If I'd have done an export for half an hour at 7.30 as planned, would this have likely heated the battery enough to get the system up and running earlier?

Thall, it has a frame around it with 3 layers of greenhouse shading to keep it cool in the summer, and I have wrapped loft insulation around the battery to keep it warm (but nothing around the AC3.0 as the installation guides say you should leave a gap around it to stop overheating).

Karen
The AC3 would run around 18C. Even Idle at -7 outside the inverter is around 14C
Batteries Idle fell to -0.5. So now will remember to 50% power charge them all night, till this crazy weather gets back to normal. Then this will just a piece of history for a few years

TheDragon (GivEnergy) I did wonder if I wasn't shoving enough juice in them last night. I had been charging a 1000-1300 on my ECO 7 nighttime charge to try to spread out the charging period as long as possible and charging to about 90-100% battery capacity. But last night because it was going to be cold and sunny today I only charged to 85 capacity and i dropped the charge to 800 to try to spread it out for as long as possible. May be tonight I should go back to 100% and 1300 charge?