When is your car battery too old?

When is your car battery too old? Car battery not holding its charge? Read on and let Haynes take all of the guesswork out of battery health.

The engine is supposed to be the heart of the car, but that’s not really the case. It’s the battery that provides the spark and that’s why you need to make sure it’s happy and healthy.

A tired old battery will let you down and it could cause electrical problems within the car’s systems. So, to avoid all that, here’s what you need to do to check your battery’s health. 

How long should a car battery last?

A car battery's lifespan depends largely on how you treat and drive your car. Do you tend to use your car for local journeys, perhaps using it once or twice a week, with the car sitting unused for days at a time? Your battery may give up the ghost in as little as three years.

If you use your car for commuting or business, and take it on regular journeys where the battery can be recharged fully, it should last at least five years and maybe more.

There's another thing to consider here, though, and that's how many times the battery goes flat during its life. Hopefully it'll always stay charged until the day it dies, but if you leave the lights on a few times and it goes completely flat, there's a good chance its life will be drastically reduced because lead acid batteries react badly to being fully depleted.

How much does it cost to replace a car battery?

Battery symbol on the dashboard

Has a battery symbol appeared on your dash? This doesn’t always mean the battery is at fault, it actually means there is a fault in the charging system. So it means the car is now relying on the power in the battery and nothing more, and it will run out quickly.

It could something as innocuous as a loose terminal or bad earth, or it could be something more serious, such as a snapped auxiliary belt or failing alternator. 

Green, black or red battery indicator

Some modern batteries have a visual indicator. If you look at the top of the battery there will be a round shaft you can look down. If it’s green, the battery has at least 75% charge, if it’s black, it needs charging, if it’s red, it’s dead.

How does the battery perform?

One of the first warnings that your car battery is on its way out is how it performs on a seasonal basis. In warmer weather, the battery doesn’t have to work as hard as it does on a cold winter’s morning. So if your car is letting you down in winter, this could well be it. 

Use a multimeter to test your car battery

The easiest way to check a battery’s health is to run a multimeter on it. You can get one for a tenner online, and then you just need to set it to volts and put the connectors on the battery terminals.

You should be seeing 12.7 volts for excellent health, 12.4 is okay, whereas anything less than 12v is a battery running out of life. Remember, the car runs on a 12v system. 

What car battery?

If you drive a 2.5-litre V6 car, but it has a dinky battery, something is awry. You need to check your Haynes manual or owner’s handbook to make sure your battery is the right size. A small battery will have fewer CCAs (cold cranking amps) and a lower AmpHour rating, meaning it will struggle with a bigger engine, or a diesel engine. 

Terminal failure

Your battery could be perfect, but if the terminal clamps on your car are covered in filth, old or battered, the battery’s power is a moot point – it can’t get past the connectors to the car. Your terminals need to be bright, clean and free from grease, dirt or any other detritus.