The battery gives your vehicle the power it needs to start the engine every day. When the battery starts to go bad, you can easily replace it. On the other hand, a bad alternator will not charge your battery properly while the car is running. The repair costs more than a dead battery if the alternator breaks down.
Signs Of a Bad Car Battery Vs Bad Alternator
If your car won’t start at all, you may have a dead battery. If your car starts for a short time and gives you that glimmer of hope that everything is fine, but then immediately stops, you probably have an alternator problem.
To figure out if it’s a dead battery or an alternator problem, grab a set of jumper cables and do a little experimenting.
Jumpstart your car. If you can turn the engine on, but it dies shortly thereafter, your car alternator likely isn’t able to charge the battery. On the other hand, if you jumpstart the car and later on it fails to start on its own, it’s likely a dead battery.
- What Is an Alternator in Car and How Does It Work?
- 7 Warning Signs of a Bad Alternator
- What Can Damage an Alternator?
Signs of a bad battery
Check for these common symptoms of a dead battery:
- Are the dashboard lights dim? First check the dashboard battery gauge. The battery should also be charged when the vehicle is switched off. If the dashboard lights are dim, there is probably something wrong with your battery. Try turning on your wipers, lights, or power windows. Then make sure these are all turned off and try starting the car again.
- Check the battery for corrosion. If it still won’t start, use a rag to gently wipe any corrosion off the battery and have someone jump-start it. After letting the engine run for a while, turn off the car. If you can’t get it to restart, that’s a sign the alternator is doing its job of keeping the battery running while the engine is running, but the battery isn’t holding the charge when the alternator has been stopped.
- The car battery could be old. As batteries age, they become less able to hold a charge because the metal inside corrodes. On average, car batteries last between 3 and 5 years. Eventually, the battery state of charge will drop to the point where no matter how much current the alternator gives it, the battery cannot hold enough current to start the car. However, there are steps you can take to extend the life of your car battery.
- Your radio will not turn on. When your ignition is on, the battery should be able to power your radio, headlights, windshield wipers, and other electronic components. If you notice your radio display or headlights flickering or dimming, there’s a good chance your battery isn’t charging well.
- Your car starts and dies instantly. This can be for a variety of reasons, but checking your battery is the best place to start. This is a strange problem that usually only occurs on certain vehicles and is due to the battery only having enough voltage to start the car.
- Your battery is swollen. If your battery is bloated, you should be able to tell thanks to the manufacturer’s design: you’ll be able to easily spot bulges in the battery’s casing. This problem occurs when your alternator has overcharged the battery due to a bad voltage regulator.
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Signs of a bad alternator
If the above steps reveal that the battery is working, it’s time to take a closer look at the alternator. There are certain bad alternator symptoms to look for:
- Dim the interior lights. When driving the vehicle, pay attention to the brightness of the interior lights. If the dashboard starts to darken, the alternator is probably to blame.
- Weak or too bright headlights. Do you notice that your headlights get brighter when you accelerate and get dimmer when you stop? This is often caused by the alternator not keeping the battery sufficiently charged.
- Growling noises. Did you hear a growling noise before the problems started? This sometimes happens before an alternator fails.
- Burnt rubber or hot wire smell. Are there any signs of your alternator overheating, such as the smell of burnt rubber or hot wires? If so, it’s time to replace it.
- Test the alternator. Some may recommend running the engine with the battery disconnected to test the alternator. However, this is not a good idea as it could damage your vehicle’s electrical system and cause major problems. Find out how to test an alternator.
How To Fix A Bad Battery Or Alternator?
If you have a bad battery, you can buy a new one at almost any auto parts store. Many stores will replace the battery as part of the purchase cost. You can also replace it yourself if you know how to do it. Do your research to find the best battery for your needs. Repairing an alternator can cost more than replacing the battery. The price you pay depends on the make and model of your car, as well as the parts and labor costs.
If your battery or alternator fails, you should take your vehicle to a mechanic and have it checked out. While the signs of a bad car battery can be obvious compared to an alternator, they can also point to other, more subtle mechanical issues.