Why Is My Battery Going Flat?
The five most common reasons a car battery keeps dying, and how to tell which one applies to you.
A battery that keeps going flat, even after charging or jump-starting, is almost always a symptom of something else rather than a one-off fault. Here's what usually causes it.
How the flat battery is behaving
- It goes flat overnight even when the car isn't used
- It's fine for a few days, then dies again
- It dies faster in cold weather
- The car needs jump-starting more than once in a week
- The battery warning light appears while driving
Most likely causes
- A parasitic drain — something drawing power after the car is switched off
- A failing alternator not recharging the battery properly while driving
- An old battery that's lost its capacity to hold charge
- Frequent short journeys that never fully recharge the battery
- Corroded or loose battery terminals reducing connection quality
How it's diagnosed
We test battery health, charging voltage from the alternator, and check for any parasitic current draw with the car switched off. This identifies whether you need a new battery, an alternator repair, or simply a terminal clean — rather than guessing.
What to do next
Repeatedly jump-starting a dying battery can mask a bigger charging fault while it gets worse. If it's happened more than once, it's worth having the battery and alternator tested together rather than just replacing the battery.
Frequently asked questions
If the car starts fine after driving for a while but dies again after sitting, it's more likely the battery. If it struggles even after a long drive, suspect the alternator.
Battery keeps dying? Let's find the real cause.