Stay Powered Up: 7 Signs You Need a New Car Battery

What do car batteries do?

Your vehicle’s battery is a critical component that it simply can’t run without.

It acts as a car’s central energy storage, allows your engine to start, and powers electrical components, such as the radio, even when the engine is off. It also helps stabilize the car’s electrical system and supports power needs when electrical demands temporarily exceed the alternator's capacity. Your car’s alternator is its primary electrical source when the engine is on, but this responsibility falls to the battery once you switch the engine off.

As electrons move from the battery’s spongy lead plate (-) to the lead-oxide plate (+), they produce electricity that moves out of the battery’s terminals to start your engine, switch on your car’s headlights, power dashboard computers, and other features like power windows and anti-lock braking systems. 

Without a functioning battery, a car won’t reliably start, and it won’t be able to power essential electronics when the engine is off. Because the battery protects and stabilizes the vehicle’s electrical system, a failing battery poses risks such as the car not starting, flickering electronics, and sudden shutdowns.

Signs you need a new car battery

Delayed engine startup

If your car’s engine takes longer than usual to turn over or sounds unusually weak when you start it, this may indicate that its battery is fading. Slow engine cranking suggests the battery’s capacity is below 70%. 

You may notice a brief pause or delay before the starter engages, or hear a rapid clicking sound when turning your key or pressing the start button. This indicates that the starter motor is attempting to engage but isn’t receiving enough current, which is another sign of low battery life. 

This is because when your car’s battery drops below about 11 volts, it no longer has the energy it needs to work the starter motor. One click on its own suggests a problem with the motor itself, but several rapid clicks tell you the car battery is more likely at the root of the issue.

Dim lights

As batteries age, they lose the ability to maintain proper voltage. This means they won’t be able to power headlights or interior lights, such as dome lights, dashboard lights, and map lights, as effectively. 

Lights that flicker or appear fainter than usual are a sign that your car’s battery might be failing. To verify that this is the issue, just switch on your car’s headlights without starting the car’s engine. If they’re noticeably dimmer, especially when the vehicle is idle, this is a red flag.

Another way to test this is to switch your engine and headlights on and rev the engine a little. If the lights suddenly become brighter, this indicates that the battery is weak.

Electrical glitches

Strange electrical glitches in car features, such as power windows or infotainment systems, are yet another sign of a dwindling battery.

If you notice that your car’s electrical parts are acting erratically or resetting suddenly, this can point to weak battery power. Windows being slow to work, radios losing preset stations, and fans changing speed without any user input are all examples of what can happen when your car battery deteriorates and the voltage dips.

Warning lights

One of the best perks of modern vehicles is their ability to monitor and alert you to potential problems, which often extends to the battery and charging systems. 

If your battery is failing, your car may display a battery symbol. This symbol sometimes appears alongside the letters “ALT” or “GEN”, and it indicates a problem with the battery or alternator.

In some cars, you’ll even see a “check engine” light if your battery is failing, because the vehicle’s computer monitors voltage and battery current levels and alerts you if something is amiss. These warnings may only appear occasionally, such as during startup or when using heavy accessories.

However, battery warning lights don’t always indicate a dead or dying battery. A low battery light can sometimes appear due to an alternator problem, faulty wiring, corroded connections, or a failing voltage regulator.

If you see a battery warning light alongside other signs, like slow engine cranking, dim headlights, or electrical glitches, though, there’s a strong chance the battery is the issue.

Rotten egg smell

If you’re driving and get a whiff of something that smells a lot like rotten eggs, this doesn’t necessarily mean you forgot old groceries in the trunk.

Inside a lead-acid battery, the reaction between sulfuric acid and lead plates creates electrical energy. This reaction is usually safely contained inside the battery, but problems like overcharging, internal short circuits, or a damaged battery case can make the reaction go faster, become unbalanced, and produce hydrogen sulfide gas. This is where the smell comes from, and it’s a signal that your car’s battery may have internal damage, be overcharging, or be cracked. 

Oddly enough, this isn’t the only thing that can cause a rotten egg smell. Poor-quality gas, old transmission fluid, and catalytic converter failure may also be the culprit, so bring your vehicle to a mechanic if the scent has you stumped.

White, green, or blue powder

A battery terminal is a metal point on a battery that connects it to a vehicle’s electrical cables.
Terminals are typically made of lead or metal coated with lead and are attached to copper cables, which let electricity flow between the battery and the car’s electrical system.

When a battery's acid leaks out, which can occur due to age, overcharging, or physical damage, sulfuric acid can react with the metal, causing corrosion that often appears in one or two forms: 

• White powder: This is usually lead sulfate or other lead compounds that form a crusty layer on the terminals.
• Bluish-green deposits: Occur when acid comes into contact with copper and forms copper sulfate. 

Both types of corrosion can inhibit battery performance, so it’s essential to clean the terminals and address leaks promptly. By mixing baking soda and water, applying the mixture to the terminals with a wire brush or an old toothbrush, letting it sit for a few moments, and then rinsing, you can keep your battery terminals clean and help maintain your car battery in good condition. Afterward, apply petroleum jelly to prevent further buildup by creating a barrier against moisture and air. 

A bulging battery case

A bulged or swollen car battery case is another indication that your battery may not be in good condition. 

Extremely low temperatures can cause a battery’s electrolyte to freeze, leading to expansion, and extremely high temperatures accelerate the chemical reaction inside your car’s battery, increasing gas production and causing swelling.

Overcharging, which occurs when a faulty voltage regulator causes excessive voltage creation, often results in heat and hydrogen gas buildup, leading to bulging as well. 

A swollen battery case can crack unexpectedly and leak harmful chemicals, which is why it's critical to replace your battery as soon as possible when you notice bulging.

When should I repair vs. replace?

Here’s the good news: not all mildly damaged car batteries are beyond repair! Repairable issues often include:

• Mild corrosion on terminals: This can usually be cleaned with the mixture of baking soda and water mentioned above. 
• oose or dirty battery cables: Tightening connections or cleaning the cable ends can restore your electrical connection.
• A drained battery: Sometimes a battery simply needs a full recharge using a compatible charger.

Visually inspecting the battery case and terminals for cracks, leaks, bulging, or heavy corrosion, along with a voltage check, can help guide your decision about whether to repair or replace the battery.

Get a tune-up at Transwest

Sick of breaking a sweat attempting at-home car repairs? Stop by a Transwest service location, and let us do the work! Our team of technicians will have you back up and running in no time.