10 Signs Your Car Battery Is Dead (Or Dying)

No one wants to be stuck in a driveway or parking lot with a completely dead car battery that won’t start again. A battery typically lasts between three and five years, depending on where you live, how often you drive the car, and your make and model. Many car owners may not realize how often they need replacing until major issues arise.

Can you get another year after jumping your battery? We’re going to discuss how to tell if the car battery is dead as well as what to look for when trying to figure out if it’s completely gone.

10 Signs of A Dead Car Battery

There are a few tell-tale signs that your vehicle’s battery is about to fail (or has failed).

Here’s a look at them:

1. No Response at Ignition

If your car doesn’t start when you turn the ignition key, it probably means the starter motor is getting zero power from a dead battery.

2. The Starter Motor Cranks But The Engine Won’t Turn Over

Sometimes, the starter motor might crank slowly, but the engine won’t start. This is a sign of either a dead car battery or a faulty starter.

If the starter cranks at the usual speed, but the engine still won’t start, you probably have a good battery, but there are issues with the fuel or spark plug.

Your lights work, the radio works, but you get a click or buzz once you hit the key. Or, your headlights are very dim. The purpose of the battery is to crank the engine by providing a full dose of high-amperage power to the starter. When the battery is low, it cannot deliver that power but often can still supply enough power for lights or accessories, that don’t require as much amperage.

Keep in mind, that jump-starting the car in these situations should only be done in an emergency. Get the battery tested as soon as possible, and do not rely on the alternator to charge the battery back up!

3. A Sudden, Slower Start

When temps drop below 20 degrees, generally any car’s starting cadence will slow down. Get below 0 and it gets even slower. If you notice this behavior suddenly and the temperature hasn’t dropped – a slow, dragging start suddenly begins, get your battery tested as soon as possible, and don’t ignore it. Eventually, the car will not start.

If a slow starting battery seems to be able to take a charge and test fine, it’s likely that a parasitic drain or draw is discharging the battery while the vehicle sits, and the electrical system will need to be looked at.

Signs of a Bad Starter or Alternator vs. a Car Battery

A bad alternator will exhibit many of the same signs of a dead car battery: dim headlights, electrical issues, difficulty starting, and a frequently drained battery. An alternator, however, will often have its own alternator light on the dashboard. Also, your car may experience unusual rattles and sounds. If you’ve replaced your battery or are thinking about it, it may be a good idea to check your alternator at the same time.

A bad starter, however, has a whole other set of symptoms. When you try to turn the key, for example, you’ll often hear a single click rather than a few rapid clicks. You won’t be able to crank the motor. You might hear a grinding noise or even see smoke when attempting to start it.

Of course, sometimes a battery is replaced and these other problems continue; you’ll want to ask your mechanic and continued issues.

4. The Engine Starts But Then Dies Immediately

This is a very strange issue that can indeed happen on certain makes/models of vehicles. The battery will have enough voltage to start the vehicle, but then it immediately dies and will not idle.

If you encounter this issue, there are a multitude of things that could be wrong, but doing a simple battery check is the first and easiest place to start. The basis behind this is when a battery fails, it can cause interruptions to the constant signals it sends to the ECU.

Then if the battery can muster enough might to start the car, the sensors controlling engine idle, speed, and fueling have already lost signal, and the car immediately dies.

5. Electrical Issues

General electrical problems are a major sign of your battery dying and could affect pretty much your whole dashboard or electrical system.

These are some tertiary signs of a bad car battery:

  • Your heated seats aren’t coming on.
  • Your dashboard or radio is working sporadically or not working at all.
  • Your dashboard lights are blinking, flickering or not coming on.
  • Your electronic windows aren’t working. Your sunroof may also be affected.
  • Your cell phone isn’t charging when you plug it in.

Of course, each of these alone might not be a guarantee of a bad battery; it’s best to check under the hood.

6. No Headlights or Dim Headlights

Your car will experience sudden electrical issues when you have a bad battery. Symptoms might include your headlights becoming less bright suddenly. They may even flicker.

This happens when the battery has just enough charge to power the headlights but not to crank the engine.  

If the headlights don’t turn on at all, then you likely have a dead car battery.

7. The Check Engine Light Turns On

The check engine light flashes or stays on constantly. Generally, this light identifies serious problems in your engine that will require costly maintenance. But you may get lucky and discover that it’s only your car battery that needs replacement.

The Check Engine light turning on could mean many things, from the alternator not charging properly to fuel mix issues.

Don’t ignore it if this light turns on. Get a mechanic to troubleshoot it ASAP.

8. Swollen Battery Size

A swollen or bloated battery is an obvious sign of a bad battery, caused by a buildup of hydrogen gases. This happens when the vehicle’s alternator is overcharging, and the battery can’t dissipate the gases fast enough.

The battery is fat, or swollen. The manufacturer designs your battery to have a specific footprint, and if the battery swells in size, you should be able to see it. If you have a bloated battery, the alternator has a faulty voltage regulator and has overcharged the battery.

This overcharging of the battery is caused by a buildup of hydrogen gases faster than the battery can dissipate. Damage to the battery has already been done and cannot be reversed.

9. Odd Smell from Your Battery

The stink of sulfur is a sign that your battery acid is leaking. Leaking battery acid is one of the top signs a car battery is dying. A dying lead battery will produce hydrogen sulfide gas, which smells like something between rotten eggs, a sewer or well water.

If you notice your lead acid battery leaking, the fluid is likely not distilled water but battery acid. Don’t touch it.

10. Corroded Battery Terminals

This is the most obvious method how to tell if the car battery is bad: Check under the hood and look where the battery is connected to the terminals (the positive and negative caps). If you see a blue-green powder or crystal-like substance caked on those terminals, it’s time to replace your car battery.

Dead batteries can be cleaned or wiped off, but this leaking battery acid is a sign of issues. It needs to be replaced immediately or very soon. For more information about how to clean car battery terminals?

FAQs.

1. What Causes a Dead Car Battery?

A dead car battery can come about because of a lot of different reasons, such as:

  • An electrical component (like the headlights) stayed on when the engine was off
  • The car hasn’t been used or driven for a long time (a fully charged battery will slowly self-discharge)
  • The vehicle’s alternator isn’t charging the battery
  • Corroded terminals reduce the charge the battery can receive
  • Low temperatures during cold weather might have frozen the battery
  • Very high temperatures in hot weather might have weakened the battery

2. Why Does the Starter Motor Grind Or Click?

Ignition clicks combined with a no-start can indicate a bad starter motor or a problem with the starter solenoid. If there are grinding sounds with a no-start, it could be the sound of the starter motor teeth misaligning with the flywheel (or flex plate) teeth.

Continuous cranking in this condition can result in more serious, costly damage.

3. Why Does the Battery Die Again After a Jump Start?

Here are some reasons why your car battery won’t hold a charge after a successful jump start:

  • The car wasn’t driven long enough for the battery to recharge fully
  • The vehicle charging system has a problem, like a bad alternator or voltage regulator
  • An electrical system was left on, draining the battery
  • The battery is too old and just can’t hold a charge

4. Can I Recharge a Dead Car Battery?

Often, a “dead car battery” simply means that it’s fully discharged and the voltage is below functional 12V. You can jump-start the dead vehicle and drive it to let the alternator replenish the battery charge.

Alternatively, you can attach the dead battery to a battery charger.

If the car battery voltage is under 12.2V, you may want to use a trickle charger to avoid battery overcharging or overheating.

5. When Is a Dead Car Battery Truly Dead?

A car battery is considered fully discharged at 11.9V. However, if the voltage drops to around 10.5V, the lead plates are likely almost entirely covered by lead sulfate.

Discharging below 10.5V can permanently damage the battery.

Additionally, if the battery is left dead, the lead sulfate eventually forms into hardened crystals that can’t be broken up by an alternator current or a regular car battery charger.

At this point, you may have to get a new battery.

6. What Are the Signs of a Bad Alternator?

You could have a faulty alternator if your vehicle:

  • Headlights are dim or overbright due to inconsistent alternator current to the battery
  • Has trouble starting or frequently stalls
  • Has a malfunctioning electrical component as the alternator isn’t supplying enough current to the battery
  • Has whining or growling sounds from a misaligned alternator belt

7. What’s an Easy Solution to A Dead Car Battery?

Finding a dead car battery under your hood can be pretty stressful, but don’t let it get to you.

An easy solution is to call a mechanic to troubleshoot issues or simply attach a new battery.