Extreme heat can damage your battery 

People aren’t the only ones to suffer in a hot car. Your battery feels it, too. How the heat affects it will depend, in part, on the specific type your car uses. But hot temperatures can damage any kind of battery.  

In this blog post, we’ll discuss the different types of automotive batteries, how the heat affects them, and what you can do to keep your car’s battery in good shape. 

Types of car batteries 

Car batteries come in two main categories: lead-acid and lithium-ion. Lead-acid batteries divide further into AGM and EFB batteries. 


Lead-acid batteries have been around for a long time. They power your car by using a sulfuric acid solution as an electrolyte. Vehicles with an internal combustion engine (ICE) usually use lead-acid batteries, which need replacing about every three to five years. With some basic know-how, you can even replace a lead-acid battery on your own. 

Absorbent glass mat (AGM) batteries are a type of lead-acid battery that contains special glass mats coated in acid to keep the electrolyte in place. AGM batteries often have a longer lifespan and therefore usually cost more. However, they’re better equipped to handle extreme temperatures than standard lead-acid batteries. 

Also in the lead-acid battery category are enhanced flooded batteries (EFB). Because they can handle more recharge cycles than standard flooded batteries (the usual lead-acid battery) and AGMs, their lifespans surpass both types. In addition to lasting longer, EFBs store more energy and are more durable than other lead-acid batteries. However, that means they’re more expensive. They typically last up to six years and are recommended for vehicles that use start-stop technology without regenerative braking. 


By contrast, almost all electric vehicles (EVs) use lithium-ion batteries because of their great charging power. Positively charged lithium ions travel from the cathode to the anode, and vice versa, to create a current of electricity. 

Lithium-ion batteries last longer (at least 10 years) and charge faster than lead-acid batteries, but they’re double the price. They’re also much heavier, and replacing them requires an automotive technician. 

Summer heat and your car battery 

Extreme heat can affect battery performance and your ability to drive your vehicle. You may even find yourself at the side of the road, calling for roadside assistance due to battery failure. 

One factor affects both batteries: heat speeds up chemical reactions, and cold (i.e., the absence of heat) slows them down. Although a battery operating in cold temperatures will show poor performance, its lifespan won’t be reduced. However, a car battery of either type operating in high temperatures will experience a reduction in lifespan. 

Now on to a few specifics. 

Heat and lead-acid batteries 

Lead-acid batteries are made of lead plates surrounded by sulfuric acid (the electrolyte). A 12-volt lead-acid battery contains six cells in which it stores the generated energy. 

When these batteries are bombarded by excessive heat, the increase in chemical reactions increases the battery’s self-discharge and causes plate corrosion, leading to a shortened lifespan. 

Heat and lithium-ion batteries 

Lithium-ion batteries contain up to several thousand cells that store the energy generated by ions passing back and forth through an electrolyte. 

In addition to increased chemical reactions, the structure of these batteries lends itself to increased problems with imbalanced charging. This is where some cells may be holding 80% of their charge, others 65%, others 15%, and so on. Ultimately, battery imbalance leads to decreased energy storage. 

Taking care of your car battery when it’s hot outside 

Of course, no one expects you to hide your car in the garage the entire summer. After all, this is the time for road trips down the long, wilderness-laden routes Canada is known for! Not to mention camping trips, overlanding, and fun weekend getaways to cottage country. 

Read on for some tips to help you keep your summer plans intact. 

Routine battery inspection 

A routine battery inspection can help detect issues with your car battery before they cause major problems. An automotive technician will test your battery’s charge and look for and remove signs of corrosion. If you’re planning a long car trip, dropping by your local NAPA AUTOPRO service centre for a battery inspection can help prevent battery problems down the road.  

(No pun intended, of course.) 

Give your car a break 

If it’s excessively hot outside, such as during a heat wave, you’ll want to stop at a few more rest stations than usual. 

For EV owners, a half-hour break can give you a chance to both cool the battery and top it up. 

Gas-powered vehicles produce much more heat than EVs. Turning off the engine for 30 minutes can counteract the extra heat in an ICE vehicle. 

Where’s the shade? 

Whether you’re stopping for a quick break, a full meal, or a full day of activities, park your car in a shady area whenever possible. Keeping the sun off your hood will do wonders for controlling your vehicle’s internal temperatures. 

Enjoy the weather 

If summer means anything to Canadians, it’s the chance to enjoy the outdoors without needing to wear a five-foot-thick layer of insulation. If you have questions about your car’s battery or want to book an inspection, visit the NAPA AUTOPRO service centre nearest you, and one of our experts will be happy to help. 

Photo: iStock-186826701