Part explained
Faulty alternator: symptoms and replacement
A faulty alternator is a slow killer: it stops charging properly, you keep driving, and one morning the car simply will not start. This page covers the symptoms, how to tell an alternator problem from a battery problem, and what replacement costs in the Netherlands.
By the onderdelen.autos editorial team · Updated
What does the alternator do?
Driven by the engine's poly-V belt, the alternator converts mechanical energy into electricity. It charges the battery and powers the electrical system while you drive. A built-in voltage regulator holds output near 14 V. Wear sits in the brushes, the regulator, or the rotor.
Signs of a failing alternator
- Battery warning light stays on during or after start.
- Headlights dim when you lift off and brighten with revs.
- Flickering or pulsing dashboard lights.
- A whining or screeching noise from the engine bay (bearing).
- Battery seems perpetually flat even after long drives.
When to replace
No fixed interval. An alternator typically lives 150,000 – 250,000 km. Replacement is reactive: change it once symptoms surface or measured output drops below 13.8 V at idle with loads on. Reconditioning an old unit (new brushes + regulator) is a common option that saves a fresh purchase.
What does a new alternator cost?
New: € 120 – € 480 depending on brand and output. Refurbished or used from a Dutch dismantler: € 50 – € 180, often with warranty. Workshop labour: 1 – 3 hours.
| Condition | From | To |
|---|---|---|
| New | € 120 | € 480 |
| Used / refurbished | € 50 | € 180 |
Compare new, refurbished and used units from Dutch sellers.
DIY?
Difficulty: Medium
On older cars, ninety minutes of work. On modern engine bays where the alternator hides behind the engine or under the intake, prefer a workshop. Always disconnect the battery negative before starting.
- Socket set
- A poly-V belt tensioning tool
- Optional: a multimeter to verify output
Frequently asked questions
Alternator or battery — how do I tell?
Measure with the engine running, loads on. 13.8 – 14.5 V is healthy. Below 13.5 V: alternator. Above 15 V: regulator. With engine off, below 12.4 V: battery.
Can I buy a used alternator?
Yes. Dutch dismantlers regularly supply them with 3 – 12 months warranty. Always cross-check the part-number plate — alternators are car-specific.
What does workshop replacement cost in the Netherlands?
Part: € 50 – € 480. Labour: 1 – 3 hours. Total: usually € 200 – € 700.
What is a refurbished alternator?
A used unit with new brushes, bearings, and voltage regulator. Often warrantied and notably cheaper than new.
Battery warning is on — can I keep driving?
Briefly, yes — but not far. The battery is now the only source of power and will run flat in 30 – 60 minutes. Drive straight home or to the workshop and switch off non-essential loads (radio, AC, rear heater).
Related parts
Alternators from Dutch inventory
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