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Car Battery 101: Everything You Need to Know

June 4, 2020

Car batteries can last for years, but they always seem to die at the most inconvenient times. In the U.S. alone, about 100 million auto batteries are replaced each year. While there are many causes of a dead battery, factory defects are rarely to blame. A little basic knowledge about how your car battery works and what to do when it fails can get you back on the road as quickly as possible.


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What To Do If Your Battery Is Dead?

There are many factors that can cause your car battery to die or lose charge. Common causes of a dead battery include leaving your headlights or interior lights on, charging system failure, corrosion, or just leaving your car parked for a long time. You can always attempt to jump start your vehicle if your car battery is dead, though it’s best to have a professional inspect the vehicle to rule out other potential issues.

The Basics Of Car Batteries

When you switch on your vehicle’s ignition via key or push-start, it signals the car battery to start a lead-acid chemical reaction. This delivers a short burst of electrical energy that enables the starter motor to crank the engine.

The amount of electric potential in your car’s battery is called voltage and most vehicles use a 12-volt battery. Even a small decrease in the voltage will have a big effect on your battery’s performance.

Once the engine is running, the vehicle’s charging system takes over. At the heart of this charging system is the alternator which maintains the battery’s charge. When a battery dies, it means its voltage has been depleted and is not being recharged.

What Causes A Dead Car Battery?

Here are some of the most common reasons that can lead to a dead battery:

Signs Your Car Battery Is Weak Or Dead

A simple way to see if your battery is dying is by turning on the windshield wipers and noting if they are operating slower than usual. Alternatively, the exterior lights and dome light on your car will appear dimmer than usual if your battery is flat, or they may not work at all.  Other signs may include:

These are some common signs that you might have a weak or dead battery.

How To Safely Jump Start Your Car

Once you’ve narrowed down the problem and suspect that you may indeed have a dead car battery, the next step is to safely jump start your vehicle. Here’s how:

How to safely jump start your car.
  1. Park the two cars close together, so the jumper cables can reach both batteries. For safety, the vehicles should be at least 18 inches apart.
  2. Put both vehicles in park (for automatic transmissions) or neutral (for manual transmission), apply the handbrake, and switch the engine off.
  3. Open both car hoods and grab your jumper cables. Note each clamp will be red to correspond with your battery’s positive (+) terminal, and black to correspond with the negative (-) terminal. Don’t let the clamps touch while you are performing this jump start as it will cause a spark.
  4. Exercise caution if the top of the battery is wet, as this is indicative of it leaking acid. Attach the positive/red clamp on the jumper cables to the positive terminal on the dead battery, then attach the other positive clamp to the functioning battery’s positive terminal.
  5. Attach the negative/black clamp to the functioning battery’s negative terminal.
  6. THIS STEP IS IMPORTANT! Connect the remaining free negative clamp to an unpainted, metal part on the car with the dead battery. A nut on the engine block is ideal.
  7. Start the engine on the vehicle with the functioning battery. Wait for a minute then start the car with the dead battery. Leave both cars running for a couple of extra minutes.
  8. Once both cars are started, disconnect the cables in the reverse order you attached them.
  9. Your car should run for around 10 minutes to allow your battery to recharge.

Best Battery For Your Car

Are all car batteries created equal? Not really, and some vehicles, such as diesels, will require a specific heavy-duty battery. To find the right battery for your car, simply put your vehicle’s details into the online Auto Battery Finder, and it will give you the details you need to know and ensure the battery will fit. You can also get an instant quote from RepairSmith or give us a call to speak with one of our helpful repair advisors.

Are You Sure It’s The Battery?

A car may not start for various reasons. While this isn’t a completely comprehensive list, here are some other common issues that may cause a car to not start, besides a dead car battery:

We suggest printing this out or saving it on your phone for emergency situations.

Worn Starter Motor

When you turn the ignition key or press the start button, the starter motor receives an electrical signal from the battery and an electrical signal spins the starter motor, engaging the crankshaft which in turn, starts the engine.

A faulty starter motor can be diagnosed by either a continuous or single ‘clicking noise’ when you attempt to start your vehicle. Starter motors have been known to die a silent death on occasion, however. You may also hear this sound if the battery is not quite dead, but unable to provide enough voltage to engage the starter motor.

Out Of Gas

It may seem obvious, but if you can’t remember the last time you filled up, your car may just be out of gas. If this happens, don’t panic. There are several ways to get fuel in your tank. You can call for roadside assistance or ask a friend or family member to help bring you gas in a gas can. You can also walk or Uber to a nearby gas station. They tend to carry gas cans, though be sure to confirm by calling ahead.

Faulty Ignition Switch

If you are positive that the issue isn’t your car battery, the ignition switch could be to blame. A sign that this is the cause of your problem is if your headlights turn on and illuminate as normal, but the car still won’t start.

Faulty Fuel Pump

Unlike other issues on this list, a faulty fuel pump is pretty easy to diagnose. When you start your car you should be aware of a faint ‘buzzing’ sound when you turn your key just before your engine cranks over. It will usually come from the rear of the vehicle and sounds like an electric motor. The sound is a signal that the fuel system is being primed in preparation for the engine to be started.

Blocked Fuel Filter

A blocked fuel filter will stop gas from reaching the engine. The fuel filter should be changed around every 30,000 miles on average to prevent this from happening.

Faulty Charging System

When the charging system fails, the battery keeps losing voltage without being recharged. A sign of a faulty charging system is lights that get dimmer as you drive or vary in brightness and you accelerate and brake.

If you need to call for roadside assistance, be sure to go through these steps before you call them as the more information you provide over the phone, the quicker they will be able to get you moving.

Get Help From RepairSmith

If you’ve attempted a jumpstart and your car still won’t start, it’s likely the fault of something other than your battery. However, if you have successfully jumpstarted your vehicle, it’s almost certainly either the battery, charging system, or electrical system that’s causing the problem.

RepairSmith’s expert mechanics will be able to diagnose the problem and give you a clear picture of your battery’s health. Do not continue to drive your car without getting your battery checked as it will more than likely die again, putting you back at square one. Replacing a car battery is better than being stuck at the side of the road. Book an appointment today.

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