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Car Doesn’t Start? Is It The Battery or the Alternator?

October 18, 2019 by Denver Express Car Care

Nothing is worse than going out to your car, turning the key, and nothing happens. You hear a slight click-click noise, but nothing happens. And if you try it again and again, even that stops.

You had plans! Now what?

If your car doesn’t start, it’s a sign that something is wrong with your starting system. It could be caused by several things, including:

  • A dying or dead battery
  • A bad alternator
  • Loose or corroded connection cables

But first, before we determine where your problem lies, it’s important to understand the differences between the alternator and the battery, and what they each do.Car Doesn’t Start? Is It The Battery or the Alternator?

The Alternator

Think of your car’s alternator as the power generator that supplies energy throughout the vehicle’s charging system. All vehicles using an internal combustion engine use an alternator.

When the engine is running, the alternator kicks into gear, charging the battery and supplying energy throughout the electrical system.

It’s bolted to the engine and is driven by a serpentine belt.

The Battery

Your car’s battery is what keeps it running. It stores energy and transforms it into power as needed.

Yet a car battery is different than other batteries you use around your home, such as in a watch or your television remote. With a car battery, the greatest thrust of power is at the time you turn the key. It needs maximum current for a short period of time to jolt the vehicle into action.

That’s known as an SLI battery. SLI stands for starting, lighting, and ignition. It sends short bursts of energy to power your lights and other accessories. But one the engine comes to life, the power to keep the car running is supplied by the alternator.

If your car is still relatively new, most vehicles are equipped with a generic SLI battery. They aren’t designed for optimum use, or for long life.

My Car Doesn’t Start – Why?

When the alternator starts to fail, the battery jumps into action and starts picking up the slack. No matter how good your car’s battery is, it isn’t designed for this level of use. It will eventually wear down, and leave you stranded somewhere along your journey.

Car batteries are not intended for long term power supply. When your car doesn’t start, it’s easy to assume it’s the battery’s fault. But there’s an easy way to determine where the problem really lies.

Jumpstart your car with a set of jumper cables. Remove them as quickly as possible once your car comes to life. Then wait.

If the car continues to run, it was likely a problem with the battery.

If the car soon dies, you’ve pinpointed it’s a problem with your alternator.

Even if you get the battery running again, keep in mind that this might be a temporary thing. Something caused the car to stop working in the first place. Even a jump start might not keep it running for very long.

You can test the battery with a voltmeter to determine its life.

What Else Should You Watch For?

Because the alternator is critical to keeping your car’s electrical system working the way it should, any mechanical problem can be a sign that something is going on with the alternator.

In newer cars, everything is computerized. You’ll have warning lights for just about anything mechanical in the system. If a problem exists with your alternator, you’ll most likely see a warning light shaped like a battery flip on. Some may also blink “ALT” or “GEN” instead. This light is telling you the car has a voltage problem. It’s in the early stages of failure.

Most alternators require 13 to 14 volts to operate your vehicle effectively. Too little, and your car will have problems working. Too much, and it will corrode the system.

You might notice other things not working as well as they once did. Since the alternator supplies electrical current, you might notice your headlights dimming, not as bright as they once were. You might notice your dash lights begin to fade. Maybe your tachometer stops working. Or the heated seats turn off before its time.

This is your car’s way of compensating for a problem. It’s putting energy to the one place that matters most – keeping your car running while warning you to pull over and stop the car.

It might also be broken or loose connections.

Electricity from your alternator runs through a series of cables and wires. If there are any problems with these cables, wires, or connections, it can stop the energy from moving from one point to another. This symptom is often accompanied by a burning smell as well. If too much power is generated to one spot, it will produce higher voltage, in effect “cooking” one area of the system. It gives off a distinct smell that warns you of potential problems.

We’ve also had cars come in with starting problems, only to discover it’s a problem under the hood. If a belt brakes, it can hang off the engine block, flapping around as you operate your vehicle. It may be missing altogether. Broken or loose belts are pretty easy to spot; open up the hood and take a peek. Even if you aren’t skilled in auto mechanics, you can usually spot a potential problem.

Because every car is different, it’s best to get in tune with your car. Watch – listen – smell – those should be things you do every time you’re in your car.

Watch for signs that something is wrong. Do you see lights on the dashboard? Do you see things that aren’t working the way they once did? Is something harder to turn? Or do certain functions disappear?

Listen for any new noise that wasn’t there before. Pay attention to clinks, buzzes, hisses, and bangs. If there isn’t a logical explanation for it, it might be your car’s way of telling you something is wrong.

Likewise, a new smell is telling you something isn’t working the way it should. You have something spilling, overflowing, leaking, or disappearing. And when each piece of your car doesn’t have the proper tools to do its job, it’s going to find a way to do it anyway it can.

Have you noticed something new with your car? Don’t let it go. At the first sign of trouble, bring your car in and let’s diagnose the problem. If could be the difference between a minor repair and a major overhaul.

Filed Under: Car Maintenance Tagged With: Alternator, Battery

Express Car Care
4200 E. Evans Ave. Denver, CO (map)
Phone: (303) 691-2760
Located just southeast of the Colorado Light Rail station

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