My car is 10 years old and I think the battery is too. She started struggling to start in the cold last winter but 24 hrs on trickle charge sorted it and she's been fine since. I'm going to buy a replacement but due to wfh and us having another car which is used daily I'm loathe to fit it straight away. The plan is to buy the replacement and keep it in the garage on a shelf and when she starts struggling in the cold I'll swap over then, but if she starts fine over the winter I'll keep the new battery in storage until needed. My thinking is I'd rather store is in a warm (well warmer) garage than on a car that is barely being given a run once per week. Will a new battery keep for a year or so with no ill effects?