CAR BATTERY HAS ' DIED '

[llamekuf]

I had been letting the engine run for 15 minutes every couple of days but alas the battery is 'dead'
The car has not been used for 4 weeks and has been sitting in sub-zero temperatures obviously.
The battery is 18 months old and the car has done very low mileage since it was installed.
As I do not think that I will need the car in the forseeable future should I leave the battery in the car and charge it when I need to use it or should I take it indoors and keep it until I need it or, should I get it charged as soon as possible and then keep it indoors or, should I put it back into the car after it has been charged and make sure I use the car more frequently.
Yes, it is obvious I know very little about cars!
Any helpful suggestions would be appreciated.

[Graham-W]

15 mins running isn't enough to replace the charge taken by the starter motor, especially if the engine is just ticking over. Recharge the battery and take the car for a good run, 30 mins+, at least once a week and it should be OK.

[llamekuf]

Thank you ZACSMASTER and DARREN197373 for your prompt and helpful suggestions.

[carlton23]

Obviously you must leave your car in the road like myself, and I am hoping mine starts to-day as it hasn`t left the kerb since before Christmas.