Going out to your car and not being able to start it is the most frustrating thing that can happen. It usually happens when you’re already late or when it’s cold in the morning. It’s especially sad when it happens over and over again. The good news is that, with a little help, it’s not hard to figure out what’s killing your battery.
If you keep reading, we’ll tell you everything you need to know. So, you can be sure that the next time you try to start your car, it will start right up.
Common Reasons Why Car Battery Keeps Dying
There are a few reasons why your car battery could keep dying even if your alternator is fine. The most likely reason is that your battery is dead. If your battery can’t hold a charge, it doesn’t matter how much power your alternator sends to it.
You might also have something that is still using power after the engine is turned off. Your alternator is run by the serpentine belt on your engine. When you turn off the engine, the alternator stops working. So, if something is using power, your battery isn’t getting charged.
This could be as simple as forgetting to turn off your headlights or radio, or it could be more complicated, like your ECU not turning off. Even if you have a good alternator, it will kill your battery either way.
Of course, you could just have a bad alternator, which would mean that your battery isn’t getting charged as it should. Or, the wiring on your alternator might be broken, so it can’t do its job right.
How to Fix It or Troubleshoot It a No-Start: A Step by Step Guide
Before you start following this step-by-step guide, you need to answer one question. Have you ever used a jump start to start your car? If so, you can use this guide. If not, you might have something else going on. Also, please keep in mind that jump-starting a car can be risky.
Look at the battery. You can check the voltage with a multimeter, but this doesn’t tell you everything. That’s because the cold cranking amps are what really start your car. To check the amps when the engine is cold, you need a special tool. The good news is that if you take your car to AutoZone, they will test and charge your battery for free.
Look at the generator. Yes, you think it’s fine, but did you really check it? If you want to know if your alternator is working right, you need to check the voltage it puts out. It should put out between 13.5 and 15 volts when it’s working right.
Check for a draw that isn’t yours. If your alternator is working and your battery is still charged, something is killing your battery. That means it’s a tie.
Make sure the wiring on your alternator is ready to go. It doesn’t happen often, but it does. The best thing to do would be to make sure that the wire from your alternator to your battery is whole and connected correctly. Corrosion can happen to these wires, causing them to have too much resistance. It doesn’t matter how much voltage your alternator puts out if it never gets to the battery!
How to check for a parasitic draw
You’ll need a multimeter with a working amp circuit to check for a parasitic draw. The fuse in these circuits will blow if you connect the leads to any voltage while the circuit is set up to test for amperage.
Before doing a parasitic draw test, you’ll need to replace a blown fuse in your multimeter.
Once you’ve set up the multimeter correctly and made sure the fuse works, you can test for a parasitic draw. Before you check for a parasitic draw, make sure that your battery is fully charged (12.6 volts).
Put the car in park and take the keys out of the ignition. You need to turn off all the lights and leave the car off for about 5 minutes. This will give your car time to turn off all of its systems before you check to see if anything is still using power.
Disconnect the negative end of the battery. Always check to see if the negative circuit has a parasitic draw. This way, you won’t short anything out.
Connect your multimeter’s black lead to the negative battery post and the red lead to the negative terminal that is not connected.
Look at the multimeter. Check to see what unit your reading is shown in if you have a newer multimeter that chooses its range for you. If it says “mA,” it is measured in milliamps. If it says “A,” it is measured in amps. If the reading is more than 100 mA, you have a parasitic draw (1 A = 1,000 mA).
What to do if you have a parasitic draw
If you do have a parasitic draw, you need to separate the circuit that is using power. The easiest way to do this is to keep your multimeter connected to the parasitic draw test while you pull fuses.
Pull out one fuse at a time and watch the multimeter to see what it does. If the amperage drops a lot, you’ve found where the parasitic draw is coming from. If the current doesn’t drop, put the fuse back in before you pull the next one.
If you pull a fuse and the current drops, but it’s still above 100mA, you have more than one parasitic draw. To keep your battery from dying, you’ll need to figure out what’s causing all of them.
Once you’ve found the circuit, you can use a cross-reference to figure out which circuit that fuse is part of. Sometimes more than one circuit runs through a single fuse, and you’ll need to unplug specific parts to figure out what’s causing the draw.
What you have to do to fix the problem depends on which circuit is causing a draw. Still, you have a place to start!
What are the Signs of a Bad Alternator?
If your alternator is broken, the most important sign is that your battery keeps dying. A dead battery doesn’t always mean that the alternator is broken, but it is the first sign that you need to look into the problem more.
If you think your alternator is broken instead of your battery, there is a surefire way to check if it is working. A multimeter or voltmeter is the only tool you will need.
You’ll need to be able to get to your alternator while the engine is on. On the back of your alternator, there is a nut with a wire attached to it. This wire sends electricity back to your battery.
Connect the positive lead of the multimeter or voltmeter to the stud while the engine is running. Connect the other wire to a good ground, such as the negative post on the battery. The voltage that comes out of your alternator should be between 13.5 and 15 volts.
If it doesn’t do this, the alternator is broken. If this voltage is coming from your alternator, something else is killing your battery.
Questions and answers:
What can drain a car battery when the car is off?
This means that you’re a parasite. When something keeps using power even after you turn off the engine, this is called a “parasitic draw.” You might have left your car’s lights on, or one of the car’s electronic parts might not be turning off when it should. Radios and lights are often used to keep people around.
Why does my battery keep dying in my car?
There are many things that could cause your battery to keep dying. You could have a bad battery, a failing alternator, or something called a “parasitic draw.”
Can a bad alternator kill a good battery?
A bad alternator can kill a good battery for sure. It can do this in two different ways.
First, your alternator might not turn off, which would cause too much voltage to be sent to the battery.
On the other hand, the battery might not get charged at all. If this happens, you’ll have to jump-start the battery more than once. When this happens, the voltage in your battery is completely gone, which can kill your battery for good.
How long will a battery last with a faulty alternator?
You will have to keep giving a bad alternator’s battery a jump start. Depending on how often you drive your car, it might last anywhere from a few hours to a few days before it needs to be jumped. How quickly your battery dies in between jumpstarts will depend on a number of things.
How long the battery will last after being used over and over again depends on how old it is. In the short term, you can kill a new battery more often than an old one, but in the long run, this will shorten the battery’s life.