He's Dead Jim 

Classic Lead Acid 'sudden death syndrome'. It's usually caused by corrosion of the positive grid; the low impedance paths end up blowing like fuses, leaving only the high impedance ones. Keeping Lead acid alive is a delicate balancing act between under/overcharge. Chronic undercharge kills faster than overcharge, but both are bad and automotive charging systems are notoriously bad. Spent too many hours of my like testing Lead acid for electric vehicle racing in the 90's.

Should get a batteriser on there.

Recently went through the dead battery game with the wife's Subaru Outback. New battery crapped out quickly. Turned out to be the built in cell phone module and is a common failure. Pulled the fuse for the useless feature and all is happy now.

"He's dead Jim", that was my thought when my computers BIOS battery read 0.7 volts (without load) and didn't even get a warning, just one specific BIOS-setting suddenly kept resetting to default (virtualization disabled) and that's it as far as symptoms went. No "replace BIOS battery" alert or anything like it... At least with cars there are obvious symptoms.

"We didn't take the EV"... didn't see that coming

4,500km in a car doesn't sound like much of a holiday - sounds more like torture.,

Thanks for all the vids, good brain fodder on a wonderfully diverse variety of levels.

the ideal moment to try the stick welder revitalize method.

Wow 4.500 KM trip in one country? Did not know that Austria is that big!

I started having issues with my 12v battery in my EV, which left me nearly stranded a couple of times inside of a week (going to the dealer soon to hopefully address this). Didn’t leave me stranded because I keep a booster box with me. I’ve used it on other people’s cars more than mine tbh. But I posted on Mastodon my frustrations and the anti-EV crowd jumped on it calling it an EV problem and why we shouldn’t be using EVs and all that nonsense. I swear they huff too much of their own fumes.

Get a jump start before buying a new battery in order to check the alternator. The meter should go well over 13v if the alienator is supplying charge to the battery

I plan on buying an EV some day. When I do, I hope that I don't develop that smug superior attitude that many EV owners seem to acquire towards ICE vehicles. They both have their place.

We bought a used 2014 Seat Leon ST 1.2 TSi to replace our rusted out 2001 Avensis 1.8.

Pays extra to "exclusively get green electricity" from the grid; takes the ICE car to do a 4500 km trip.

Check that there is no corrosion between the terminals and battery post, I noticed your meter was connected to the posts and not the terminal itself. Driving with a bad battery will wear out your alternator.

Looks more of a terminal connection issue to me, strange that the battery was good enough to start the car to get you there, but now is so bad it won't even support turning ignition on

I built a supercap / LiFePO₄ hybrid for my car. Works OK, but the size LiFePO₄ that I could fit has a lot less capacity, so standing for weeks or operating radio, etc while car is off can sometimes drain it...

A small handheld lithium battery jumper would get you home or too your local auto store to replace the battery. Lead acid batteries over 5-6 years old are going to strand you.

Not all EVs use lead acid. Tesla switched to 16v Lithium for their low voltage system late 2021 or early 2022.

Charged lead-acid car batteries open circuit voltage couldn't be under 12.8V. In Sydney's climate, it's good to service them out of the vehicle twice a year (ones a year charge plus 20 hours discharge and a full charge and the second time just charge to 100%), unless vehicle is driven every day for not less than 25km after each engine start. If the vehicle stays mostly stationary it's good to top the battery each month.