A car battery that sits for a few days or a week should not go dead but if you allow your car to sit without starting it for months at a time then the car battery could go dead.
That is even more true during cold weather as cold weather can cause a car battery to lose it's charge and get weak so it could be hard if not impossible to start your vehicle in cold weather if you allow it to sit too long.
Sometimes in really cold weather my truck takes a few cranks to get it going because the battery gets a little weak but it eventually starts.
If your car is gonna sit longer than a week I would put a charger on the battery for at least 4 hours every few days to make sure the battery stays charged up and so that you don't wake up to a dead battery when you need the car.
If your car does more sitting than driving then the battery can die a quicker death but driving your vehicle more often and keeping the battery charged up helps to extend the life of the battery.
Cold weather can also wreak havoc on car batteries and deplete some of the charge due to a chemical reaction which changes during cold weather.
So in cold weather make sure you put a charger on the cars battery if not driving it often.
Or drive the car more often even around town for 5 or 10 minutes to keep the battery charged up.
The longest I've had a vehicle battery last was in a truck and it lasted me 15 years and was an interstate battery.
Interstate batteries are pretty good quality batteries even though they are more expensive than cheaper batteries but in my opinion interstate batteries are good quality and long lasting batteries.
There's no way to know for sure if the interstate batteries will last 15 years today or not but you should get 8 to 10 years at least out of one.
Some good quality car batteries can last 10 years and even 15 years which has happened to me.
There's no guarantee that a car battery will last you longer than 10 years or even 5 years but the battery that I had last me 15 years was an interstate battery that I had in a truck.
I bought it 15 years ago at the time it died.
I was never expecting the interstate battery to last 15 years and I was maybe expecting 8 to 10 years at most but surprisingly the battery lasted me 15 years so I got my money's worth from it.
However if your battery today is a cheaper battery and it's 5 years old or older then I would be saving some money to get a new one before it leaves you stranded.
Most batteries today last at most 5 to 7 years depending on the battery brand.
The cheaper brand of batteries usually don't last as long.