Signs of a dead car battery

Wednesday 20th December 2023

A flat battery is one of the most common reasons your car won’t start, but it doesn’t happen without warning. Colder weather,?short journeys?and long periods parked up are some of the biggest causes. This guide covers what causes a battery to die, the signs to watch for and how to tell a flat battery from a failing starter motor, and what to do next.  

What causes a car battery to die? 

Cold weather: Low temperatures slow the chemical reaction inside the battery reducing its ability to hold charge. Find out why your battery keeps dying in the cold.  
Short journeys: Frequent short trips don’t give the alternator enough time to fully recharge the battery after starting the engine.  
Long periods of inactivity: A car left sitting on the drive for weeks or months slowly loses its charge, even if nothing is left switched on.  
Battery age: Batteries wear out over time and hold less charge as they get older.  
Lights or electrics left on: Interior lights, headlights or infotainment systems left running while the engine is off will quickly drain the battery.  

What are the signs of a dead car battery?  

Warning light on the dashboard: A battery symbol appearing on your dashboard is usually the clearest sign of a problem. 
Slow or delayed starting: A struggling battery usually gives one or two weak starts before it fails completely. Once it's fully flat, turning the key or pressing the start button produces a clicking noise rather than the engine turning over. 
Headlights appearing dimmer: The battery powers more than just the engine. If your headlights look dimmer than usual, or the radio and electric windows feel sluggish, a flat battery is the most likely cause. 
Unusual smell from the battery: Your car battery should have no smell. A sulphurous or rotten-egg smell means the battery has vented gas and may be leaking sulphuric acid, which can damage surrounding components. 

 Flat battery or bad starter? How to tell the difference 

A flat battery and a failing starter motor can cause similar symptoms, so it's easy to mix them up. Here's how to narrow it down before you call for help. 
 

Signs of a flat battery 

• The dashboard lights, radio and electric windows are dim or unresponsive. Not just the engine. 
• You hear a single rapid clicking sound when you turn the key. 
• The problem has built up gradually, with several slower starts.  
• A jump start gets the car running again.  

Signs of a bad starter motor 

• The dashboard lights and electrics work normally, but the engine won’t turn over.  
• You hear a single loud click, a whirring noise or nothing at all when you turn the key or press the start button.  
• The problem appears without warning. 
• A jump start does nothing.  

If you’re still unsure, a free battery health check will confirm whether the battery or the starter motor is causing the issues..  

What to do if your battery has died 

If your?battery has died, you may be able to jump-start it?with two jump leads, ?using the power from another vehicle’s engine to give out a boost of energy to kick-start your own battery. Alternatively, you may need to charge your battery using a battery charger. Learn more about?how to charge a car battery?here. 

How long should a car battery last? 

Generally,?car batteries last around 3-5 years. However, this depends on various factors – such as what type of battery you have, temperature extremes, taking frequent short trips and any long periods of inactivity. 

Replacing a car battery 

In some instances, you may need to fully replace your car’s battery when your battery has reached the end of its lifespan and cannot hold a charge. To start, you will need to identify?what car battery you will need. 

Here at Formula One Autocentres, we offer a free battery check and can fit a new replacement battery if your old battery is dead. Simply search for your nearest Formula One Autocentres branch to book your next battery health check now.