Short answer: Slow cranking, a battery warning light, electrical glitches and a start-stop system that no longer switches the engine off are the common signs of a weak battery. Heat shortens battery life, so batteries in Singapore often wear out sooner.
Common signs
The engine turns over slowly before starting, the battery or charging light comes on, lights flicker or the car shows random warning messages, the start-stop system stops working, or the battery case looks swollen.
Heat is the real enemy
High temperatures speed up the chemical reactions inside a battery and the loss of water from it. That is why batteries in hot climates tend to fail sooner than the same battery in a cool one, often with little warning.
Battery or alternator?
A battery that keeps going flat may be fine and simply not being charged, or something may be draining it while the car is parked. A load test of the battery and a check of the alternator output tell you which.
Start-stop cars need AGM or EFB batteries
Cars with start-stop restart the engine many times a day and need a battery built for it: AGM (absorbent glass mat) or EFB (enhanced flooded battery). Fitting a standard battery in their place shortens its life and can stop start-stop working.
Battery registration
Many European cars adjust their charging to the battery's type and age. After a replacement, the new battery is registered or coded to the car with a scan tool so it is charged correctly.
