This guide is general information. Stop driving and seek appropriate assistance if the vehicle is unsafe, seriously overheating, losing braking or steering control, or showing another urgent warning.
The systems work together
The battery supplies energy for starting and stabilises the electrical system. The alternator recharges it while the engine runs. A weak battery can stress the charging system, while poor charging can leave a healthy battery flat.
Useful test conditions
Battery condition, resting voltage, cranking performance and charging output under load all provide different information. Connections, drive belts and current drain may also need attention.
- Slow cranking
- Battery warning light
- Dimming or unstable electrics
- A battery that goes flat after standing
Why a recent battery can still go flat
A new battery will not solve a charging fault, parasitic current drain or poor connection. Repeated discharge can also damage the new battery, making early diagnosis worthwhile.
Send the full history
Tell the garage when the battery was replaced, how long the car stands, whether the warning light appears and whether starting changes after a longer drive.
Related garage service
Alternator Repair & Replacement
Read the service page or send your vehicle details to Arnold Lane Service Centre.
