Car won't start. Then jump it and fine no matter how many times start stop.

[Stig88]

Hi everybody,

I took the kids to school this morning, on getting back in the car it wouldn't start. Like the battery was dead. Got the wife to come out with the jump leads, as soon as I connected them and went to start the car it fired straight up. I have done several short start stops today and it's been fine since. The battery is only 3 months old. Any ideas.