Weak or flat car battery: signs and solutions
On a cold morning the starter motor turns slowly, or does nothing at all. A weak or flat battery is one of the most common reasons a car will not start. Modern cars also demand more and more from their battery. In this article, XCS Automotive in Merchtem explains how to recognise a weak battery, what the causes are and when it needs replacing.
What does the battery in your car do?
The 12V battery supplies the power to start the engine. It also powers the electronics when the engine is off: the central locking, the alarm, the control units and the memory for the radio and settings. As soon as the engine runs, the alternator recharges the battery.
Hybrid and electric cars also have a 12V battery, in addition to the large traction battery. If that small battery is flat, even an electric car cannot start.
Signs of a weak battery
- The starter motor turns more slowly than usual, especially in cold weather.
- The dashboard lights flicker or dim when starting.
- The start-stop system no longer works, or works less often.
- The clock or settings reset after starting.
- Strange error messages appear in the electronics.
- The car does not start after standing for a few days.
If the red battery light comes on while you are driving, it is usually not the battery itself but the charging system. The alternator is not charging properly and the car is running on the battery's reserve. Switch off as many power consumers as possible and drive straight to the garage.
Why does a battery go flat?
Age
A battery loses capacity over the years. How long it lasts depends on the type, the use and the conditions. A battery that is already several years old and struggles in the cold is often due for replacement.
Short trips
Starting the car uses a lot of power. If you mainly drive short distances, the alternator does not have enough time to put that power back. So the battery gradually runs down.
Long periods standing still
Even when the car is switched off, the electronics use a little power. If the car stands for weeks, the battery can run flat.
Cold
At low temperatures a battery delivers less power, while the engine needs more force to start. That is why many drivers discover a weak battery in winter.
A consumer that stays on
A light in the boot, a door that does not close properly or a faulty module can drain the battery overnight. If this happens regularly with a good battery, we look for the cause with a diagnosis.
The battery is flat: what now?
You can start the car with jump leads and a second car, or with a jump starter. Always follow your car's owner's manual, because on some cars the connection points are not directly on the battery. Then let the engine run for a while and have the battery tested. A battery that was completely flat may have been damaged.
If starting does not work or you are unsure, call us. Anywhere in Merchtem we collect your car free of charge.
Replacing a battery: mind the type
Replacing a battery sounds simple, but on modern cars there is more to it. Cars with a start-stop system often have a special type of battery, such as an AGM or EFB battery, which copes better with frequent starting. An ordinary battery is not suitable.
On many recent cars a new battery must also be registered in the electronics. That way the battery management knows a new battery has been fitted and charges it correctly. If this is not done, the new battery can age faster or the start-stop system may not work properly.
We choose a battery that meets your car's specifications, fit it, register it where necessary and check the charging system. You receive a price in advance. You get a 1-year warranty on the work carried out.
How to look after your battery
- Take a longer drive now and then, especially if you mainly cover short distances.
- Switch off heated seats, the rear window heater and other consumers when you do not need them.
- If you will not be using the car for a long time, consider a maintenance charger suitable for your battery type.
- Have the battery tested at your service, especially before winter.
At a minor service we always test the battery. Read more about our services at maintenance and repairs. For the cold months you will find extra tips in our winter checklist.
Frequently asked questions
How do I know whether the battery or the alternator is the problem?
With a test we measure the condition of the battery and the alternator's charging voltage. That tells us which part is the cause.
Can I fit a new battery myself?
On older cars you can. On many recent cars the battery has to be registered and the right type matters. If in doubt, let us do it.
My electric car will not start. Could it be the 12V battery?
Yes. An electric car also has a 12V battery that powers the electronics. If it is flat, the car will not start.
How much does a battery test cost?
At a minor service we always test the battery. If you only want a test or a diagnosis, we charge the time needed.
Battery tested or replaced?
Book your appointment online via make an appointment or call Jorne on 0471 46 40 17 or Quinten on 0470 56 61 21. You will find us at Stoofstraat 43 in Merchtem, open Monday to Friday from 8 am to 6 pm and on Saturday from 10 am to 5 pm. Anywhere in Merchtem, we collect your car and bring it back free of charge.