Like a Doctor, But For Your Car

What's The Difference Between Battery Testing And Load Testing?

If you're concerned about your car's battery, you've probably come across the terms "battery testing" and "load testing." Testing your battery is critical to avoid the frustration, cost, and embarrassment of having your battery suddenly fail. Battery testing is also essential to rule out other problems with your charging system, such as faulty alternators or grounding problems.

However, not all battery testing methods are the same, and it's critical to understand the differences so that you can reliably determine if your battery is still good enough to start your car.

How Automotive Batteries Work

Automotive batteries typically fall into a category known as "starting" batteries. Other standard batteries include deep-cycle and hybrid, although these are usually only used in marine applications. Starting batteries don't like deep discharges. Instead, these batteries deliver a single, quick jolt of power, such as what's required by your starter motor to get your car moving.

Once your battery supplies this initial burst of power, it essentially stops acting as a primary power source. Your alternator generates the electrical energy needed to run accessories such as your headlights and turn signals with your engine running. Your battery remains in the circuit but acts primarily as a capacitor to ensure smooth, even, 12-volt power delivery.

Discharging a starting battery too deeply will cause internal damage to the battery. Although the battery may still charge and function, its lifespan is likely lower after a deep discharge event, and it may leave you stranded. Testing your battery can help reveal these problems and allow you to determine if you should replace your battery sooner rather than later.

Battery and Load Testing Explained

Load testing is a more reliable and accurate method to test a battery. Since your car's battery needs to provide enough cold-cranking amps to start your engine, it's not enough to simply determine the voltage when the vehicle is off. Instead, load testing checks for voltage drop once the starter engages. If the voltage falls too low, the battery can't supply adequate power to turn the starter.

Load testing has numerous advantages over simply hooking up a multimeter to your battery. For example, technicians can use load testers with the battery outside of the vehicle. Since a load tester provides a starter-equivalent load, it allows a technician to test your battery even if your vehicle won't start, allowing them to narrow the problem down to the battery itself.

While placing a multimeter on your battery can quickly estimate its current charge, it won't necessarily tell you everything you need to know about its health. A load tester is a more reliable diagnostic tool that can help you determine if your battery is failing or if you have another issue preventing your car from starting.

For more information on battery testing, contact a professional near you.