Signs your car battery is dying, and how to tell battery from alternator from starter

What are the early signs of a weak car battery?

Most batteries give some notice before they quit. In Abu Dhabi heat the notice can be short, sometimes only a few days, so it is worth acting the first time you see one of these signs.

The one drivers overlook most is start-stop switching itself off. Many assume the system has developed a fault, when it is simply the car protecting a tired battery.

• Slow crank: the engine turns over lazily, and it is most obvious on the first start of the day.
• Start-stop stops working: the car keeps the engine running at traffic lights because it no longer trusts the battery to restart it.
• Dim lights at idle: headlights or cabin lights that brighten when you press the accelerator.
• Warning messages: a battery symbol, a low battery or energy management message, or electrical features switching themselves off.

What are the signs a car battery needs replacing now?

These are no longer warnings. A battery showing any of them should be tested before the next trip, and the last two mean the car should not be jump started at all.

A swollen or smelly battery can vent flammable gas. Keep sparks and cables away from it, leave the bonnet open if it is safe to do so, and have it replaced.

• Rapid clicking when you turn the key or press the start button, with the engine not turning.
• Needing a jump start more than once in a few weeks.
• A swollen or bulging case, caused by overheating or overcharging.
• A rotten-egg smell, which is sulphur gas from a battery that is being overcharged or has failed internally.

Is it the battery, the alternator or the starter?

The three faults feel similar from the driver's seat, but each leaves a different pattern. Use the table as a first guess and then confirm with a test, because guessing wrong means paying for a part the car did not need.

Car won't start, clicking noise, but the lights come on

This is nearly always a weak battery or a bad connection, even though the lights seem to prove otherwise. Lights and screens need a few amps. A starter motor needs several hundred, and a battery can supply the first long after it has lost the ability to supply the second.

The rapid clicking is the starter solenoid pulling in, losing voltage, dropping out and trying again. Watch the cabin light as you turn the key. If it nearly goes out, the battery or its terminals are the problem.

One heavy click with lights that stay bright is a different story. The battery is doing its job and the starter is not, so neither a jump start nor a new battery will change anything.

Why does my car battery die overnight?

Either the battery can no longer hold a charge, or something in the car is drawing from it while parked, which is called a parasitic drain. Every modern car draws a small standby current for its alarm, clock and computers, and a healthy battery carries that for two or three weeks.

The order of checks matters. Test the battery first, because an old battery is the more common cause and the quicker fix. If it passes and still goes flat overnight, the drain has to be measured with a meter and traced circuit by circuit, which is workshop work. These are the usual sources.

• A boot, glovebox or vanity mirror light that stays on
• A dashcam wired for parking mode
• An aftermarket tracker, alarm or audio amplifier
• A control unit that does not go to sleep after the car is locked
• A charger or accessory left in a socket that stays live

What does the battery light mean while driving?

It means the charging system has a fault, not that the battery is old. The light comes on when the alternator stops charging, most often because of the alternator itself, its drive belt, or a wiring or connection fault.

From that moment the car is running on whatever is stored in the battery, and it will stop when that runs out. Switch off what you can spare, keep the engine running and head for the nearest safe place to stop. Abu Dhabi highways post minimum speeds, so on the E10, E11 or E22 that means the next exit or service road, not the hard shoulder if you can avoid it.

A new battery does not fix this. It will get you a little further and then go flat as well.

What to do in Khalifa City when your car will not start

Stop cranking after two or three tries. Each attempt takes more out of a weak battery, and long cranking overheats the starter.

We come to the car at any hour, usually within 20 to 35 minutes inside Khalifa City, which many people still call Khalifa City A, and we test the battery, starter draw and charging for free before anything is replaced. If a jump start is all the car needs, that is all it gets. Four small steps make the visit quicker.

• Note what happened: slow crank, clicking, one click or nothing. It tells the technician what to bring.
• Check that both battery clamps are tight, without touching a swollen or leaking battery.
• Switch off the lights and AC, and unplug anything in the sockets.
• Send your location on WhatsApp or call, and say where the car is: driveway, basement, school car park or roadside.