MALAYSIA has roughly two types of parking: shaded spots that everyone fights over and the vast, sun-blasted open-air car parks that most people end up in.
Every Malaysian who has ever returned to a car that had been baking in the sun for four hours knows the particular misery of touching a metal seatbelt buckle.
But beyond the scorched fingertips and the steering wheel that doubles as a grill, there is a more pressing question. Is all that heat actually killing the car battery?
Verdict:
TRUE
The heat is absolutely doing damage, but not quite in the way most people imagine, and the worst of it is happening somewhere most drivers never think to look.
First, a quick explanation of how car batteries work.
Most cars on the road today use what is commonly called a maintenance-free or sealed battery, which generates electricity through chemical reactions between lead plates and an electrolyte solution absorbed into a fibreglass mat inside the casing.
Older cars may still use conventional flooded lead-acid batteries, where the electrolyte sits as free liquid around the plates.
Both types are sensitive to heat, though sealed batteries handle it somewhat better than conventional ones.
The optimal operating temperature for both is around 25°C, which in Malaysia is essentially a cool day indoors, and certainly not the reality of a car park under open sky.
Research confirmed that chemical reactivity inside a battery roughly doubles for every 10°C increase in temperature, which sounds useful until the implications sink in.
More chemical reactivity in an idle battery sitting in a hot car park meant the battery was working against itself, slowly self-discharging and degrading even when no one was driving it.
A peer-reviewed study published in the journal Battery Energy in 2023 by researchers at Arizona State University, specifically examining sealed lead-acid batteries at temperatures between 25°C and 40°C, found that higher temperatures caused measurable degradation of the electrode and grid materials inside the battery, resulting in shorter cycle life, reduced discharge capacity and increased internal resistance.
The study confirmed that the damage accumulated progressively with sustained heat exposure.
Now here is the part most drivers never consider.
The battery does not sit inside the car's cabin. It sits in the engine compartment, which gets significantly hotter than the cabin.
Multiple peer-reviewed studies measuring temperatures inside parked cars found that cabin temperatures reached 70°C to 80°C under direct sunlight in hot climates, with dashboard surfaces approaching 100°C.
Engine compartment temperatures ran even higher than the cabin, meaning the battery was regularly being exposed to conditions well above the 40°C threshold at which the Arizona State University research had already found accelerated degradation.
For conventional flooded batteries, this level of heat was particularly damaging because the liquid electrolyte evaporated faster, exposing the lead plates and causing early failure.
For sealed maintenance-free batteries, the electrolyte was absorbed into a fibreglass mat rather than sitting as free liquid, making them more resistant to direct evaporation loss.
However, a 2025 peer-reviewed study published in the Journal of Solid State Electrochemistry confirmed that excessively high temperatures adversely affected the internal chemistry of AGM sealed batteries, negatively impacting both performance and service life over time.
The US Department of Energy recommended storing batteries at temperatures between 10°C and 25°C for optimal lifespan, a range that Malaysian outdoor parking conditions routinely and dramatically exceeded.
The good news was that the damage was cumulative rather than immediate.
One hot afternoon in a car park was unlikely to kill a healthy battery on its own.
But weeks and months of daily parking under direct sunlight in Malaysian heat added up, and drivers who habitually parked in the open were measurably shortening their battery's lifespan compared to those who found shade.
Automotive engineers consistently recommended parking in shade wherever possible, using a reflective windscreen sunshade to reduce heat build-up and checking battery terminals regularly for corrosion, which appeared as a white or blue powdery residue and was one of the first visible signs of heat damage.
For a country where shade is a luxury and the sun operates twelve months a year with zero days off, that was easier said than done.
But at least now there was a scientific reason to justify the ten-minute walk across a multi-storey car park to find that one blessed shaded spot.
Sources:
1. https://onlinelibrary.wiley.
2. https://link.springer.com/
5. https://www.energy.gov/
