Repairs
Alternator Replacement
The alternator keeps the battery charged and the electronics fed. When it fades, the car will usually run until the battery runs out — and then stop.
Battery light on while driving?
Symptoms of alternator failure
- Battery or charging warning light while driving
- Dim or flickering headlights, especially at idle
- Repeatedly flat battery despite a new battery
- Whining or grinding from the alternator
- Burning smell from the belt or alternator
- Electrical items behaving oddly or the car cutting out
What we test
- Charging voltage and current output under load
- Voltage drop in charging cables and earths
- Auxiliary belt, tensioner and pulley condition
- Smart charging control on vehicles that use it
- Battery condition, because a failed battery can imitate this fault
Related work
Alternator work usually means removing the auxiliary belt. Where the belt or tensioner is worn, replacing it at the same time saves labour later. Vehicles with a battery sensor or smart charging may also need coding after a battery change.
Frequently asked questions
Symptoms
Symptoms that often lead to this repair
Look up what your car is doing and read what it commonly means.
Car won't start and just clicksClicking means the electrical side is trying to work but the engine is not turning over properly. The pattern of the clicking is the most useful clue.Read more Battery warning light on while drivingThe red battery symbol is a charging-system warning. The engine is normally running on stored battery power only, which is limited.Read more Whining noise when acceleratingThe useful question is whether the whine follows engine revs or road speed, because that separates belt and turbo noises from gearbox and differential noises.Read more Flat battery: why it keeps going flatBatteries do wear out, but a battery that flattens repeatedly usually has help — either it is not being charged properly or something is draining it while the car is parked.Read more Signs your car battery needs replacingMost batteries give warning before they leave you stranded. Recognising it early usually means choosing when the car is off the road rather than being told.Read more Car battery keeps going flatRepeatedly flat batteries are rarely bad luck. Something is either draining the battery, failing to charge it, or the battery itself is finished.Read more
Related
You may also need
Car Battery ReplacementModern batteries are not just a box of power. On many vehicles a new battery has to be the right type and registered to the car.Read more Car Won't Start?A car that will not start is not one fault — it is a shortlist. Working through that list in order is how you avoid buying parts you did not need.Read more Starter Motor ReplacementStarter faults are often blamed on the battery and vice versa. Testing tells them apart in minutes.Read more Car Diagnostics & Fault Finding in IverA warning light tells you something has been detected — not what has failed. We diagnose the vehicle first so the repair that follows is the repair the car actually needs.Read more
Talk to us about alternator replacement
Based in Iver, covering West London, Berkshire and South Buckinghamshire. Send your registration and we will quote for your vehicle.