Battery Shopping? Your Guide to Diesel Semi-Truck Battery Voltage

How many times has this happened to you? You take your seat at the wheel, turn the key…and it starts working right away!

If that sounds mundane, it’s because of the hard work put in by a truly underappreciated component—the humble battery. Without functioning batteries, your trucks wouldn’t just have trouble getting where they need to go. They wouldn’t be able to turn on, period.

The batteries in your trucks can be easy to overlook, but taking some time to think about their condition will pay off. Whether you’re wondering if you need new batteries or want to make sure you’re getting the perfect semi-truck battery voltage, you’re in the right place.

Here’s what you need to know about heavy-duty battery shopping.

Is It Time to Buy a New Battery?

On average, the lifespan of a vehicle’s battery will fall somewhere between three and five years. Consider buying a new battery for your truck if your current battery is in or near this age range and it:

• Won’t recharge properly. In many cases, batteries that can’t hold a charge are reaching the end of their service life.
• Needs constant jump-starts. Jump-starting your battery every so often won’t hurt it. But if your battery needs jump-starts regularly, it may be time to swap it out.
• Has trouble getting started in the cold. Batteries that normally have trouble holding a charge will fare even worse when dealing with freezing temperatures.

Even if a truck has encountered one of the aforementioned issues, the battery may not be directly responsible. It could be a non-battery issue masquerading as a battery issue. It’s all too common to see these signs, replace the truck batteries prematurely, and not get the maximum value out of the batteries as a result.

Instead, you could be dealing with:

Poorly-Secured Cables
If your battery cables aren’t properly secured to your terminals, you can’t expect your truck to start correctly. Be sure to check your battery connections on a regular basis to avoid this.

Parasitic Loads
Anything that draws from a battery but doesn’t resupply power is considered a “parasitic load.” Your trucks will always deal with parasitic loads to some extent, especially when they’re turned off. Still, it’s wise to ensure these loads are as limited and infrequent as possible.

Battery Vibration
A battery that isn’t correctly secured will have trouble functioning—and could sustain significant damage. Drivers should double-check that their batteries are secure before heading out.

Alternator Issues
The alternator is responsible for charging a vehicle’s battery. Still, this component can have trouble performing this task in certain situations (for example, if the voltage it puts out is incorrect). Whenever drivers check the batteries, they should take a peek at the alternators, too.

Battery Corrosion
Corrosion on your battery terminals occurs when these components come into contact with hydrogen gas (which can be found in battery acid). This condition can make it harder for your battery to charge. Small amounts of corrosion are normal and can be cleaned off, but more significant corrosion may indicate that your battery needs attention.

Semi-Truck Battery Voltage

If your battery can’t do its job and the issues listed above aren’t to blame, it’s probably time to go battery shopping. When buying new batteries for your fleet, your first concern should be semi-truck battery voltage. Batteries with too much voltage for your trucks could cause damage, but batteries that don’t deliver enough voltage could prevent electrical components from turning on or working correctly.

In North America, most semi-trucks require 12-volt batteries. These often take the form of three batteries working in parallel to generate 12 volts. On the other hand, many international trucks take 24-volt batteries (which may really consist of four six-volt batteries in a series).

Since this can vary based on your truck’s model and manufacturer, check your user’s manual for voltage information before purchasing batteries.

Other Battery Factors

Getting the proper semi-truck battery voltage is essential, but it’s not the only factor you’ll need to consider when buying batteries. Along with that, take some time to think about:

Cold-Cranking Amps
Cold-cranking amps (CCA) is a rating of how effectively a battery can crank an engine when it’s cold outside. More specifically, this measures the number of amps your new 12V battery can support at 0°F for 30 seconds while maintaining 7.2V. If you live in a cold climate, CCA should be one of your primary considerations.

Reserve Capacity
Also known as “RC,” reserve capacity keeps your truck’s electrical systems running if your battery fails. This number indicates how long your battery can maintain a 25-amp load before fully discharging. As is the case for CCA, the higher your RC, the better.

The Future of Heavy-Duty Truck Batteries

Right now, truck batteries have the essential job of helping diesel trucks get started and power their electrical systems when they aren’t running. 12V and 24V are standard on the market right now, but that might not always be the case.

With technology like smart trailers requiring even more power on the road, we may see the standard battery voltage for semi-trucks increase in the years to come. And that’s not even mentioning fully electric trucks and other alternative fuels that are set to make a splash in the heavy-duty world.

(Just don’t literally “make a splash” with fuels—your crew already has enough to deal with.)

Whether tomorrow’s fleets are powered by electricity, hydrogen, or Soylent Green, Fullbay will be there to help. Better yet, you won’t have to wait years to take advantage of our cutting-edge heavy-duty repair software. Fullbay can handle your service order workflows while giving your technicians valuable wiring diagrams and procedures right now. Set up a demo to get started!