Charging/alternator issues
Battery light, dim lights, random errors. Confirm charging voltage and belt condition before replacing parts.
HIGH RISK
Common symptoms
- Battery light on
- Voltage low
- Electrics glitching
- Stalling / no-start after driving
Cost expectations
DIY: £0–£80. Garage: £150–£450.
Note: prices vary by car and region. Use this as a planning range.
Most likely causes (ranked)
- Alternator/regulator fault — Undercharging or overcharging.
- Belt/tensioner — Slipping belt reduces output.
- Bad battery — Loads system and masks charging problems.
- Ground/connection — Voltage drop causes symptoms.
- Parasitic loads — Not a charging issue but drains battery.
Quick checks (fast, low-cost)
- Measure voltage at battery: engine off and running.
- Check belt condition and tension.
- Check for voltage drop between alternator and battery (advanced).
- Scan for charging-related codes (some cars).
- If voltage is unstable, avoid long drives.
Recommended tools
These tools make diagnosis faster and stop you buying random parts.
Related fixes
If your symptoms don’t match perfectly, check these next.
What to do next
- Charging faults can strand you — treat as urgent.
- Start with measurements, not guesses.
- Fix connections before replacing alternator.
AutoSolveHub helps you narrow possibilities. Always confirm critical repairs with proper testing and safe procedures.