Summer heat and car battery: What you need to know

Does heat damage the car battery?

Yes, heat can damage a car battery, whether it’s a lead-acid battery or another type of battery. In summer, the temperature under the hood of your vehicle can reach 150°C (302°F), or even higher on very hot days. Such exposure to excessive heat accelerates battery wear—sometimes up to three times faster than in cold weather temperatures. This can lead to rapid discharge, sudden failure, or reduced performance. 

What are the warning signs of a weak or failing car battery?

A dying battery shows several weak car battery symptoms: 

• Slower engine start than usual, especially after sitting idle for a while. 

• Headlights that appear dimmer or weak interior lighting. 

• Battery warning light appearing on the dashboard. 

• Sulphur smell (similar to rotten eggs), which may indicate a leak or overheating. 

These symptoms suggest that your car battery is discharging faster than it recharges. 

How to prevent premature car battery wear in summer

Your car won’t start in summer? Follow these simple steps to prevent battery wear and reduce the impact of heat on it:  

• Park your vehicle in the shade or inside a garage to avoid extreme temperatures. 

• Avoid short, repeated trips during hot weather, as they prevent a full recharge. 

• Turn off electrical accessories (AC, radio, headlights) when starting the vehicle. 

• Use a thermal battery cover (available at the CAA-Quebec Boutique) if your car is exposed to high heat for long periods. 

• Have your starting system inspected by a professional and get your battery tested regularly. 

These precautions will help you extend the lifespan of your car battery during heatwaves or hot summer days. 

How to maintain your car battery in summer

Here’s what you can do for proper car battery maintenance: 

• Clean battery terminals if they are dirty, as poor contact can prevent the engine from starting. 

• Have your electrical system inspected by a professional if your battery is more than three years old. CAA-Quebec Battery Service patrollers will test the battery, starter, alternator, and charging system. You’ll receive a detailed diagnostic report, letting you know if a replacement is necessary to avoid a breakdown. 

• Replace your battery immediately if the case shows swelling, cracks, liquid leaks, or unusual odours. 

How to keep your battery charged in summer

Low battery usage reduces performance, especially in hot weather. This often happens if you leave your car parked for too long, such as during summer vacations. To prevent a dead battery when you return, use a slow battery charger plugged into a standard outlet, ensuring the batter pack remains at full charge.   

What to do if the battery warning light turns on

If the battery charge light turns on in the dashboard, reduce the use of electrical accessories and consult a mechanic right away. A failing charging system can cause sudden loss of all electrical assistance, putting your road safety at risk. 

Electric vehicle battery: Should you worry about heat?

Electric vehicles (EVs) use a lithium-ion battery pack, which is different from a standard 12-volt battery but still sensitive to extreme temperatures. 

In summer, the EV traction battery can overheat. Over time, this may affect performance and reduce driving range. Fortunately, most EVs are equipped with advanced thermal management systems (liquid cooling or active ventilation) that help maintain an optimal temperature. Still, it is recommended to: 

• Park in the shade to avoid extreme heat. 

• Avoid repeated fast charging during heatwaves to reduce thermal stress. 

• Use the preconditioning function (if available) to cool the battery before charging. 

These precautions will help maintain your EV range and extend your EV battery life.