What does an alternator do?
The alternator is the device responsible for generating electricity to charge the battery. It’s coupled with the engine drive, which means whenever the car is running, the battery is being charged. Without a charged battery there is no delivery of power to the electrical components or to generate the sparks used to combust the fuel in the engine.
How often should an alternator need replacing?
An alternator typically lasts around 7 years or between 100k and 150k miles.
The law, vehicle regulations and your MOT
Without a correctly functioning alternator, your car is unlikely to hold enough charge in the battery to drive for any purposeful length of time. Having said that, the alternator won’t be tested during an MOT, so as long as the battery has enough charge for the engine and other electrical components to run for the duration of the examination, then it can still achieve a pass.
We do not recommend this in any circumstance. If there is a problem with your alternator, you should have it repaired or replaced as soon as possible.
What causes an alternator to stop working correctly?
An alternator might break down due to a bearing failure, preventing the rotor from spinning freely. Fluid leaks or a too tight belt (or a loose belt slipping) can also cause damage and premature wearing.
Symptoms of a malfunctioning alternator
When the battery is flat
If your battery is flat and refuses to accept charge through normal driving, then your alternator could be the problem.
The lights aren’t as bright as normal
If your headlamps aren’t as bright as normal or the function of other electrical components is weak, your alternator may not be supplying as much charge to the battery as it needs.
The battery warning light is illuminated on the dashboard
All warning lights are an indicator that a sensor has detected a failed component or poor operation. A battery warning light could be connected to your alternator performance.