Why Texas heat is so hard on your car battery

Why is heat harder on a car battery than cold?

Cold gets the blame because that is when cars refuse to start, but heat does much of the damage. A car battery makes electricity through a chemical reaction. AAA explains that heat speeds that reaction up, but it also increases the rate at which the battery breaks down. AAA names time, heat and vibration as the three things that decide how long a battery lasts.

Battery maker VARTA puts a number on it. Chemical activity inside a battery roughly doubles with every 10°C (18°F) rise in temperature, and more activity means more corrosion of the lead grids inside. Battery manufacturer Clarios adds that heat increases water loss in conventional flooded batteries and gradually reduces how well a battery holds a charge.

How hot does it get under the hood in Dallas?

Dallas summers are long. Using records that go back to 1899, the National Weather Service puts the average first 100-degree day at Dallas/Fort Worth on July 1 and the average last one on August 27. In 2011 the area logged 71 days at 100 degrees or more, the most in a single year on record.

Under the hood it gets hotter still. AAA says engine compartment temperatures can easily exceed 200 degrees Fahrenheit in hot weather, and Clarios notes that engine compartments run especially hot in stop-and-go traffic and during long idling. That is the heat a battery sits in on a summer afternoon in traffic. It is also why AAA notes that some automakers put a heat shield over the battery or relocate it altogether.

How many years does a battery last in Texas heat?

AAA says most batteries wear out gradually over three to five years, but climate moves that number a lot. In cooler northern climates a battery may last five years or longer. In hot southern climates, AAA says it typically lasts about three years.

That is why the age of your battery matters so much here. AAA recommends having a battery tested every year once it reaches its third year. The test shows how far it has deteriorated, so you can replace it on your own schedule instead of in a parking lot. AAA also notes that some failing batteries show no obvious symptoms, so a battery that seems fine is not proof that it is healthy.

Why do car batteries die after summer is over?

Heat damage builds slowly. Clarios notes that drivers often don't notice it until months later, when a weakened battery struggles to start the car. VARTA describes the same pattern. The aging goes unnoticed through summer and fall, then shows up in winter, when the engine needs more energy to start.

The most confusing version, according to VARTA, is a battery that still has enough power for the lights but is too weak to start the engine. It looks fine until the moment you need it. So if your battery struggled through August, don't assume it is safe once the weather cools.

What are the warning signs of a heat-damaged battery?

Watch for these signs from AAA and Clarios, especially once your battery is more than three years old. Any one of them is a good reason to get the battery tested before it leaves you stuck:

• The engine cranks more slowly than usual when you start it.
• The battery or charging warning light comes on.
• Headlights or interior lights look dim.
• Electrical accessories seem weaker than normal.
• The battery is over three years old and hasn't been tested recently.

How can you make a car battery last longer in the heat?

You can't change the weather, but you can take some of the strain off the battery. These steps come from AAA and Clarios:

• Park in the shade when you can, so the car isn't baking in direct sun.
• Make sure the battery is held down tight. AAA says loose or missing hold-down hardware can shorten its life significantly, because vibration breaks down the parts inside.
• Keep the cable connections clean and tight, and have the battery inspected at every oil change.
• Limit accessory use, like the radio or charging a phone, while the engine is off.
• If the car sits for long stretches or you mostly drive short trips, use a maintenance charger to keep the battery fully charged.
• Get the battery tested before a long summer road trip.
• When you replace it, match the group size, type and terminal layout your vehicle calls for. Don't go below the cold cranking amp rating the manufacturer recommends. AAA notes that a higher rating is usually unnecessary and may have a shorter service life in hot climates.

What should you do if your battery dies in the heat?

A dead battery also means no air conditioning, and a parked car heats up fast in a Texas summer. NHTSA warns that rolling the windows down or parking in the shade does little to change the temperature inside a vehicle, and that a child's body temperature rises three to five times faster than an adult's. Never leave a child in the car while you wait, even for a few minutes. If you ever see a child alone in a locked car, call 911.

In a parking lot, wait somewhere cool and safe nearby and keep your phone handy so dispatch can reach you if they need one more detail. On a highway, Texas DPS tells drivers to get as far off the traveled part of the road as they can, switch on the flashers and climb out the passenger side, away from traffic. Then wait well clear of the lanes, never between the car and passing traffic. Call 911 first if the car is stuck in a live lane or someone is hurt.

How Pit Stop helps with a dead battery in Dallas

Pit Stop Roadside Services is open 24/7 at (214) 367-5302, and in Dallas the typical wait for a technician is 30–45 minutes. After a jump start, the technician can check the battery and charging system, which helps show whether the battery is worth keeping.

If it isn't, the technician can replace it with a new battery where the car is, whether that's your driveway, your office or a store parking lot. The dispatcher confirms the right battery for your vehicle and when it can get there, and quotes the price on the call before anyone drives out. That is what you pay for the job you described.