If you're wondering why an electric car even needs a 12V battery at all when it has a great big battery *right there*, the short answer is "to turn the big battery on".

When an electric car is "off" the big traction battery is disconnected, for safety. It has a separate low voltage power system to power all its auxiliary systems, including the relays that reconnect the traction battery when the driver turns the car back on. A dead 12V battery means you can't reconnect the traction battery, so you're stuck. In this sort of situation it is possible to "jump start" an electric car, though.

BYD Atto 3's had a spate of 12V battery issues when they first came to Australia, due to a combination of poor quality lead-acid batteries and bugs in the software that managed the 12V battery recharging. I gather they have since been largely resolved, and all the BYD EVs that have come to Australia since (Seal, Dolphin, Sealion 7) use LFP battery packs for their low voltage power instead and I haven't heard of anyone having trouble with those.

Grid power was restored at 1.22 am (17 hours 43 minutes after it went out) but I was in bed by then so our car continued to supply power to our fridge-freezer, WiFi, etc. overnight. By the time I disconnected everything from the V2L adaptor it had been providing power for us for 24 hours and used a total of 7.2 kWh in that time, leaving the car battery at 91%.

The V2L adaptor goes back into its storage spot in the sub-basement of the boot, and I've decided to keep one of the 30 metre extension cords and the power board box in the frunk just in case I need them when on the road.

So far so good. The scheduled power outage started about 7:40 am, but I was able to quickly restore power to the fridge-freezer, the NBN box & WiFi router, the lizard's heat lamp and lighting, and my working from home monitor, laptop, etc.

I have the Vehicle-to-Load adaptor plugged into the car, two extra heavy duty 30 metre long extension cables plugged onto that inside a weatherproof power board box, and a mess of additional power boards and extension cords inside the house. Fortunately, apart from the fridge which is directly connected to the V2L adaptor, it's all very low power so having lots of long cables will be OK.

Being able to work from home pretty much as I normally do on Wednesdays is nice, but not having to worry about everything in the freezer defrosting is really, really nice.

Making sure I'm prepared for the scheduled power outage in two weeks.

Our BYD Seal came with a vehicle-to-load adapter, which is a ~5 m long cable with a Type 2 plug on one end and a 2 outlet mains power board on the other. By itself that's only good for supplying mains power to my driveway so I also have a 30 m extra-heavy duty extension cord, plus a weatherproof power board box to protect the connection from rain.

The main reason I laid this out today was to confirm that 30 m is the right length for the extension cord, and I was pleased to find that it does reach inside our house far enough to comfortably reach our fridge, or our living room. If I now get a second 30 m extension cord I can use the other outlet on the V2L adaptor and preserve both our food and our internet connection while the power is out.