How do you know when a car battery has seen better days.

A couple of times recently the engine has been a bit hesitant to start, the car and i assume the battery is 4 years old, wondering if this hesitation indicates the battery isn’t as good as it once was?

Pop to Halfords and get them to test it, they have a computer thingy that checks it’s condition. Prob have one at your local garage too.

Ideally get it load tested, but failing that multi-meter and note how low the voltage drops to, during starting when engine is cold.

basic test, it should be holding 12.6 or 12.7v after resting for a while. 12.4v is 50% charge which is essentially flat for a lead acid.

Anything much over three years old is pushing it theses days.