Rainy season puts car batteries at risk as air conditioning, dashcam use surges

As the rainy season and summer heat set in, proper vehicle battery management is becoming increasingly important. Summer brings heavier use of air conditioning, dashcams and other electronics, and the combination of high temperatures and humidity can accelerate battery degradation and the risk of discharge.

Hankook & Company announced Thursday that it has released a guide on how to inspect and maintain vehicle batteries during the rainy season.

The Korea Meteorological Administration declared the start of the rainy season in central regions of the country on Tuesday. Heavy rain is forecast mainly for Jeju Island and the southern coast from early July, while inland areas are expected to see continued heat.

According to the agency's three-month outlook for July through September 2026, there is a 60 percent probability that average temperatures in both July and August will exceed seasonal norms. Rainfall in July is expected to be near or above average, each with a 40 percent probability.

High temperatures can accelerate chemical reactions, self-discharge and corrosion inside lead-acid batteries, reducing their performance. The load on batteries grows further as drivers increase their use of air conditioners, dashcams, navigation systems and other electronics.

Warning signs of battery trouble include a weakened starter motor, changes in headlight brightness and a faint horn. Debris accumulating around battery terminals can impede current flow, so periodic cleaning with a brush is recommended.

The method for checking battery condition varies by type. Maintenance-free batteries can be assessed quickly by checking the color of the indicator on top — green generally means normal, black means charging is needed, and white means replacement is required.

AGM batteries can be harder to assess by indicator alone, and using a voltmeter or multimeter is advisable in those cases. If the pre-start voltage reads below 12.4V or starting problems recur, the battery's charge level and overall condition should be inspected.

Caution is also needed when parking for extended periods in summer. Prolonged exposure to outdoor heat can cause electrolyte evaporation and voltage instability. Parking indoors or in the shade is recommended where possible, and drivers who leave their vehicle unused for long stretches should start the engine at least once a week to keep the battery in good condition.

Running electronics for long periods with the engine off should also be avoided. Dashcams in particular continue drawing power while the vehicle is parked, so drivers leaving their car for an extended time should enable power-saving mode and check battery voltage regularly.

Battery management is equally important in vehicles equipped with idle stop-and-go systems. ISG is designed to operate normally only when battery voltage is above a certain level, meaning the function can be restricted if voltage drops too low.

To help drivers find the right battery for their vehicle, Hankook & Company operates a license plate-based battery search service on the official Hankook Battery website. Entering a license plate number returns compatible battery products matched to the vehicle model and year.

The same license plate-based battery lookup is available on T'Station.com, the online platform of T'Station, Hankook & Company's automotive service center chain. The company also offers next-day installation through its e-commerce channels.

Hankook & Company is expanding its AGM battery lineup, with a focus on vehicles with high electrical loads and those equipped with ISG systems. AGM batteries offer superior charge-discharge performance and durability compared with conventional batteries, making them well suited for vehicles with heavy power demands.