A conventional car battery lasts four to six years in normal use. Start-Stop batteries (EFB and AGM) are built for harder duty but live a similar span in practice, because the duty really is harder. Those averages hide the interesting part: how you use the car moves the needle more than the badge on the battery.
What shortens a battery's life
- Short trips. Starting takes a big bite of charge; a 10-minute drive doesn't pay it back. A car that only does school runs and supermarkets lives permanently undercharged — and chronic undercharge sulphates the plates.
- Long immobilisation. Alarms, trackers and control units draw current 24/7. A few weeks at an airport long-stay can take a middle-aged battery below cranking threshold; months of storage can finish it.
- Heat. Counter-intuitively, hot climates kill batteries faster than cold ones — heat accelerates the chemistry that ages the plates. Cold doesn't destroy the battery; it just exposes the damage by cutting available power on the morning you need it.
- Vibration and corroded terminals — both fixable, both worth a look under the bonnet twice a year.
The warning signs
- The engine cranks noticeably slower, especially on cold mornings.
- The Start-Stop system stops cutting the engine at lights — many cars quietly disable it when the battery weakens. It's an early warning most drivers miss.
- Dash lights dim during cranking; electric windows slow down with the engine off.
- The battery is over four years old and any of the above sounds familiar.
Before a long trip through France
A battery that behaves at home can still fail after the motorway-and-parking pattern of a holiday: a long drive, then a week or two standing still. If yours is past its fourth birthday, have it load-tested before you leave — any garage can do it in minutes, and so can we at your door. And if it fails while you're already in France, an English-speaking technician can test it where the car stands and replace it on the spot if the verdict is final.