Most people know that cold weather affects battery performance in your heavy-duty truck. But what about the effect of summer heat on your truck batteries? The fact is, extreme heat can also be detrimental to battery life.

Some lead acid batteries can suffer water loss in extreme heat — and water is essential to the electrochemical process within the battery.

Lead acid batteries function using an electrochemical process in which lead plates react with an electrolyte. As the temperature rises and a battery absorbs heat, the process speeds up exponentially. This results in an increase in plate corrosion, self-discharge, and over a prolonged period, sulfation. 

Sulfation is the development of large crystals on the negative plates, blocking surface area and impeding battery performance.

It's Not Just Summer Heat That's Affecting Today's Truck Batteries

There are other factors that expose heavy-duty batteries to excessive heat other than the ambient temperatures.

Over the past decade, truck designs have been focused on achieving better aerodynamics to improve fuel mileage. In these design modifications airflow is directed over, above and behind the vehicle. That means less air flow to cool the engine and other heat-generating components in the engine compartment and underneath the vehicle. 

On top of that, the position of the battery box is closer to heat generating components. 

In short, the battery is in a hotter location that isn’t as efficiently cooled. As a result, temperatures can reach 140 degrees and higher.

Simply stated, batteries discharge faster in excessive heat. 

Unless the battery design includes features that help protect the battery from the heat, or if preventive measures aren’t taken, battery life and performance are likely to be affected. 

It is estimated that constant exposure to heat above 77 degrees cuts battery life in half for every 15-degree rise in temperature.

Watch Out for Parasitic Loads That Affect Your Truck Batteries

Another factor to consider in the summer — and all year-round for that matter — is parasitic loads. 

Many of the electronic accessories and systems both in and out of the cab can create parasitic loads that will drain the battery to discharge.

Parasitic loads are small currents, typically of a few milliamps (mA), that the battery must deliver continuously to function properly. Although small, they have a large effect. As the battery is slowly discharged without immediate recharge, sulfation is a common result.

High temperatures, especially when combined with parasitic loads, will shorten the life of the battery. 

Knowing that the summer heat already speeds up the rate at which the battery deteriorates, and that the rate of deterioration is further accelerated by parasitic loads, managing these two important factors can help increase the reliability and longevity of the battery.

3 Things You Can Do to Protect Your Heavy-Duty Truck Batteries in Summer Heat

1. Choose your heavy-duty truck batteries wisely. Selecting a battery that stands up better to excessive heat is a good place to start. Non-spillable, maintenance-free AGM [absorbed glass mat] batteries manufactured with thin plate pure lead (TPPL) technology can perform in extreme temperatures as high as 176 degrees. They also offer slower self-discharge rates, less corrosion and faster recharging than alternative battery chemistries.
2. Know your battery is fully charged. You can’t assume that vehicles in use every day recharge their batteries. Because excessive heat causes faster discharge, it is a good practice to use a maintenance charger on idle vehicles exposed to excessive heat.
3. Keep track of the installation date. Plan to replace your battery within the manufacturer’s recommended time frame. Knowing that excessive heat can influence battery life, there’s no need to press your luck.

All things considered, there isn’t a lot you can do about summer temperatures. 

However, you can put yourself in a better place down the road by knowing how heat affects a heavy-duty battery — especially when it comes to buying a new battery or getting longer battery life from the product you already own. 

Always be sure to follow the manufacturer’s guidelines for battery care and handling and direct any questions to your battery professional.

About the author: Alan Kohler is senior marketing manager, Odyssey battery,at EnerSys. This article was authored under the guidance and editorial standards of HDT's editors to provide useful information to our readers. Opinions may not reflect those of HDT.