Quick Facts About Car Batteries
- The older your battery is, the more likely it is to fail or die.
- If your car’s headlights lose brightness, flicker, or fail to illuminate, these symptoms may indicate a weak battery. Another sign of battery trouble is the engine not turning over.
- When replacing a car battery, one size doesn’t fit all.
A car battery usually isn’t on a driver’s mind until it’s a dead battery. And, like those in your flashlight, failing car batteries are never convenient. However, the battery in your vehicle may show warning signs of its demise, in which case you can act quickly before you find yourself in a situation you don’t want to be in.
8 Signs Your Car’s Battery Is Dead or Dying
Symptoms of a failing/failed battery might be attributed to problems with other components, such as the starter, alternator, or other electrical parts.
Although a new battery failing is not impossible, the older your battery is, the more likely one of our warning signs below will indicate it is failing or dead. Signs include:
1. Illuminated Battery Warning Light
Unsurprisingly, you have a battery-related issue if the battery warning light in your gauge cluster illuminates. It may not be a complete battery failure, but whatever the problem is, it will probably eventually impact battery efficiency or life.
2. Engine Won’t turn over
You turn the ignition key, and nothing happens. Or maybe you hear a clicking sound. The engine not turning over is a signal that either your battery is already dead or there is very little power left in it.
3. The Engine Is Slow to Turn over
Hearing a low moan or a series of moans when you turn the ignition key — even if the engine eventually starts — might indicate you have a dying battery.
4. The Engine Starts But Immediately Dies
As a battery fails, it may have enough juice to start the engine but not enough to keep it idling for a few seconds until the electric system fully functions.
5. No Dome Light
Unless you’ve turned off the function or the fuse is blown, if you open a car door and the interior lights don’t illuminate, that’s a sign of a failed or failing battery.
6. Dark, Dim, or Flickering Headlights
Your car’s headlights losing their brightness, flickering, or not illuminating at all are issues that point to battery failure. The likelihood of battery trouble is stronger when dim lights happen along with one or more of our other warning signs.
7. Signs of Fluid Leakage
Evidence that your car’s battery is leaking or has leaked (such as dried fluid on the battery or in the battery tray) indicates something amiss with its operation and structural integrity.
8. Battery Box Integrity
If the structure that contains the battery is swollen or cracked, it’s time to replace the battery.
What Causes a Dead Car Battery?
Age is the top cause of a dead car battery, but there are plenty of other causes as well. These can include extreme temperatures, corrosion, leaving lights on inside or out, a bad alternator, and more.
What to Do if Your Car Battery Dies
When a car won’t start, the first thing to do is pop the hood and check for a dead battery. You may be lucky to find the issue is a loose or dirty connection at one of the terminals. If so, correct the problem and try starting the engine again.
If a terminal connection isn’t the answer, you will need to start your car with another process — this typically means jump-starting it using the battery in another vehicle or a portable jump-starter.
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Take Action
You should keep a set of good-quality jumper cables in your car and know how to use them. You’ll also need another vehicle with a compatible 12-volt battery and someone willing to help you jump your car. A portable jump-starter can be another solution and is a handy device to keep in your vehicle.
Unless you know the battery died because of accidentally leaving the headlights on overnight or another obvious cause, you should have the car battery tested as soon as possible. Any repair shop, dealer service center, and many auto parts stores can test the battery. If such a test reveals that the battery is failing, replace it.
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How to Choose a Replacement Car Battery
One-size-fits-all doesn’t always work, and there certainly isn’t a single solution for a replacement car battery. A battery needs to be the appropriate size to function efficiently, have sufficient cranking power, and have the terminals in the correct position for your car.
5 Things to Consider
- Battery group size: This refers to the battery class that will best fit your vehicle’s physical dimensions, including the terminal location. Your car’s year, make, and model require a specific battery group size. Usually, the larger the size, the higher the level of starting power. You can find the group size on the battery you are replacing or in your car’s owner’s manual. They look like 24, 24F, 27, 34, and so on.
- Reserve capacity: This is a measurement of the actual time a car battery can power essential accessories on its own. Why is that important? It tells you how long that battery can keep devices operating and so forth once the engine stops running. The figure also indicates how long the power will last if the alternator dies.
- Cranking amperage: In battery terms, cranking amps are basically a cold-weather measure. It’s the number of amperes (a base unit of electric current) a battery can deliver for 30 seconds at 32 degrees Fahrenheit. You will also hear the term “cold cranking amps,” which sounds redundant but isn’t. This is a separate rating for the number of amperes a battery can deliver for 30 seconds at a temperature of zero degrees. The second measure is crucial if you live in the Snow Belt.
- Freshness date: We tend to think more about freshness as a measure for a gallon of milk than we do for a car battery. Still, the more recent a battery’s manufacture date, the more distant its “best by” date would be — if they had them. Six months probably won’t make much difference in the greater scheme of things, but a year or more could.
- Warranty: Batteries fail. Some fail sooner than others. As with anything else, there’s no certainty regarding longevity. When purchasing a new car battery, buying one with a warranty spanning at least two years is best. Several battery manufacturers offer warranty coverage for more extended periods. For example, Interstate Super Premium and DieHard Platinum batteries have 48-month free-replacement warranties.
How Much Do Car Replacement Batteries Cost?
Car battery prices vary considerably depending on the vehicle, battery size, technology, capacity, brand, warranty, and where you purchase it.
Current retail examples show conventional Group 35 batteries ranging from about $80 to $155, while comparable absorbed glass mat (AGM) batteries can approach $190 to $205 or more. See more on AGM batteries below.
Remember, with so many aspects to weigh, zeroing in on an average price for a new battery won’t tell you much. Moreover, when it’s time to replace a battery, you have little choice but to buy one, right? You can then choose among compatible batteries that meet your vehicle manufacturer’s specifications.
Keep in mind that a refundable battery core charge and installation fees can also factor into the total cost.
How to Extend Your Car Battery’s Life
Every battery will die eventually. However, you can take a few precautions, like ensuring all the interior and exterior lights are off when you exit the vehicle. Newer vehicles may have exterior lights that turn off automatically, but manually controlled systems leave this task for you. Even an interior map light left on overnight can drain an older battery.
Performing some battery maintenance as part of routine car maintenance can also prevent issues down the road. Ensuring the terminals are clean and corrosion-free is a good starting point. If the battery has fill ports, checking the fluid levels and topping them off with distilled water helps prevent lead plate corrosion.
What Shortens a Conventional Car Battery’s Life?
- Shake, rattle, and roll: A conventional car battery’s multiple-plate design allows for the shaking and vibrating of plates as the car drives along the road. All that jostling of the plates and sloshing of the electrolyte solution creates wear and tear.
- Low electrolyte solution level: The electrolyte solution can leak out of the battery or boil out if the alternator malfunctions and overcharges the battery. Reduced levels of the battery solution can expose the lead plates, leading to corrosion and reduced battery efficiency.
- Intense hot and cold: Extreme temperatures can also shorten a battery’s life and performance.
Conventional Batteries vs. Absorbed Glass Mat (AGM) Batteries
AGM batteries are more compact and lighter than conventional car batteries and are literally maintenance-free. Although they still use lead plates surrounded by an electrolyte solution, a glass-mat separator is between the lead plates. These fiberglass mats attract the electrolytes and store them in a dry state. As the need arises, the electrolytes transfer to the lead plates to create a charge.
Because of the glass-mat construction, AGM batteries discharge more slowly than conventional ones. In other words, they retain their charge longer. This makes them ideal for today’s highly technological vehicles with many devices and electronics. AGM batteries also recharge more quickly than conventional batteries. Furthermore, because of the tighter packing of the battery elements, there is much less vibration than in conventional batteries. This design reduces wear and tear.
Although the average AGM battery costs more, it is more efficient, requires less maintenance, holds its charge longer, and will outlive a conventional battery by two to three years. Advantage: AGM.
Conventional vs. AGM: What They Are, and Which One You Need
Both are lead-acid batteries. The difference is what holds the acid — and that one change drives everything else.
Conventional (Flooded)
Lead plates sit in a free-flowing liquid electrolyte — sulfuric acid and water — sloshing inside the case. It’s the standard car battery of the last century: proven, inexpensive, and vented, which is why some designs need water topped off.
AGM (Absorbed Glass Mat)
Same lead-acid chemistry, but fiberglass mats between the plates soak up the electrolyte and hold it in a dry, suspended state, releasing it to the plates as charge is needed. Aerospace-derived, fully sealed, spill-resistant, and maintenance-free.
So which one is right for you?
Tap everything that sounds like your car
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Loaded with screens and electronics
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Has automatic start-stop
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Short trips, or parked for weeks
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Rough roads, towing, or off-road
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Older, basic vehicle
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Cheapest option is the priority
Either
Start tapping
Tell us about your car
AGM is the better battery on almost every measure. Conventional still wins on upfront price — so the right answer depends on what your vehicle actually asks of it.
How a Car Battery Recharges
Although a reaction within the battery provides an extra burst of electric power to start the engine, a battery merely stores electric energy. An alternator is key to recharging and maintaining a battery’s charge.
Once the engine runs, the alternator siphons off some of the engine output via a belt and pulley, thus transforming mechanical energy into electrical energy. It then transfers that electric energy to the battery to recharge it.
A healthy new battery can repeat the discharging-charging process tens of thousands of times. However, it will eventually lose its capacity to recharge. Therefore, a conventional battery will fail in three to five years under average conditions.
Here’s the catch: A conventional battery’s core efficiency lies in starting the engine. It will produce a trickle current to keep the headlights, radio, and so forth running for a limited period after the engine disengages. However, the battery is not engineered for that. Therefore, the existing charge rapidly runs out in the battery when the engine stops, just like the battery in your flashlight.
Conclusion
Although proper maintenance, minimizing exposure to temperature extremes, and avoiding rough driving surfaces can extend the life of a car battery, it is finite and will eventually fail. By being alert to the warning signs of a failing battery and replacing it before you find yourself stranded when it’s least convenient or safe, you can save yourself some time and heartache.
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This article has been updated since its original publication. Russ Heaps contributed to the original report.