You know the sickening feeling when you turn the key and engine barely turns over? Well read on to find out what to do…
Is it definitely the battery?
If your car won't start and you suspect it's the battery there are several signs. The first most obvious one is that the car turns over a lot more slowly than usual.
If the car turns over strongly (like normal) and the car's not starting it's likely to be something else, possibly electrical – immobilisers are often guilty of this, and sometimes a fix is as simple as locking and unlocking the car and trying again!
If you turn the key and the car's completely dead check to see if any lights have been left on, and if so that's your culprit. If the car makes an audible click but nothing else happens that's generally a sign that the battery's flat!
If nothing happens at all, no click, no dashboard lights, no signs of any lights being left on check the battery terminals aren't loose.
If you're sure it is the battery, and jump starting it isn't possible you're going to want to know how to charge the battery.
How to charge a car battery
- If you're sure the battery is flat (because you left the lights on) you can connect a mains battery charger (which cost upwards of £20) which you connect straight to the car battery. You can either do this with the battery in situ, or you can take the battery out first.
- Battery chargers are fairly self explanatory; connect the + and the – to the battery terminals and turn the charger on! Most have lights to tell you the state of charge and when it's full.
- It's strongly advised not to do this indoors – as a faulty battery (or charger) can potentially cause an explosion and/or a fire!
How to test the car battery
- There are fancy battery testers that monitor the condition of the battery, but you can do a simple battery test with a basic multimeter (which start at around £10). Turn the dial onto the 20V setting and connect the red probe to the + side of the battery terminal and the black probe to the – terminal.
- It will then give you a voltage reading. 12.6v means there should be sufficient to start the car – so if it's not starting and you're reading 12.6v then the battery isn't at fault.
- If it's reading lower, then you may experience issues, and it's any lower than 12v it's technically flat, so starting will be virtually impossible.
- Incidentally with the engine running the voltage should be between 13.8v and 14.4v.
