How to Know When Your Alternator, Starter, or Battery is Going Bad
Your car won’t start? What’s the problem? The battery? The alternator? Something else? I’m here to help! Check out this picture guide to help you determine what could be causing your vehicle not to start!
The Top 5 Reasons Your Car Won’t Start
By far the most common reasons a car won’t start (if it has been running recently) is an electrical issue of some sort. These are the top reasons your car won’t start. Sure there can be a lot of other reasons, but these are the most common culprits. Check these things first!
- A drained battery.
- Bad electrical connection.
- A bad battery.
- An inoperative alternator.
- A bad starter
Before we explore these in detail, let’s discuss a little bit about each of these parts and how they interact.
The battery in your car is like a reservoir for electricity. It is constantly being ‘used up’ and ‘refilled’ based on what the car is doing at any given moment. By far the most taxing task that the battery has to contend with is starting the car. This definitely takes the most amount of power that the battery is going to need to expend. Other functions of the battery are to power anything else electrical in your car, for example the radio, or the cigarette lighter.
The alternator is a device that charges the battery. The alternator is powered by the engine. So ultimately, the ‘power’ for the alternator is the gasoline that you put into your tank. The engine turns the alternator coil through a belt, and that spinning coil generates electricity that is then pumped into the battery, charging it up.
When your car is off, and you go to start it, obviously the alternator is not charging the battery. So in order to turn the starter motor to get the engine running, your car will use the electricity stored up in the battery. If everything is working as it should, the battery will have sufficient power to turn the starter motor, which will then turn the engine (the engine will “turn over”), and the car will start.
The other component to consider here are all of the connections that run between the battery, the alternator, and the starter. If any of these connections is not good (loose, corroded, frayed, or disconnected), the electrical circuit may be broken, and electricity will not be transferred properly.
I hope this brief explanation is helpful. Now, let’s go through each of these problems in a little more detail. We’ll talk about how you will know if you have each problem, as well as what you should do about it if that is your problem.
#1 – A Drained Battery
A drained battery usually results from the lights or some other electrical device such as a radio, being left on overnight. A car battery, like any other battery, when being used will drain down over time if it is not charged up. If the car is not running, the battery is not being charged, and the battery can drain low enough that it does not have the amperage to start the car. Interior lights left on are another common cause of a drained battery.
How do I know if I have a dead battery?
- Car won’t start or slow cranking
- Clicking sound when turning the key
- Headlights dim or won’t turn on
- Other electrical components inoperative or weak
Usually you will know you have a dead battery when you turn the key to start the vehicle, and nothing happens or you experience slow cranking. If the battery is not completely dead, but drained down, you may hear a click or clicking sound from the starter.
A good way to check is to try turning on the headlights or internal lights with the key in the ON position. If the headlights don’t come on, or they are very dim, this indicates the battery is dead.
Tip: Sometimes the battery may have enough juice to turn on the lights, just not enough to turn the starter motor (which takes significantly higher amperage).
What do I do if I have a dead battery?
If you have a dead battery, get some jumper cables and ask someone else in another car to give you a jump start. Or use a portable car jump starter.
If you have a battery charger, use this to charge the battery fully (usually takes about 15-30 minutes), then try starting the car again.
#2 – A Bad Electrical Connection
Bad connections are probably the most difficult of these problems to diagnose, but the good news is that it is usually one of about 3 connections: the 2 battery terminals, and the grounding cable. Check these three connections and clean or tighten them if necessary.
How will I know I have a bad electrical connection in my car?
- The car will start intermittently
- Intermittent electrical problems
- Car won’t start on wet or rainy days
- Battery terminals are corroded
Because electricity requires a good tight connection where metal touches metal in order to pass through, a bad connection will restrict the flow of electricity. Depending on things like the atmospheric pressure and humidity, the car starting or other electrical devices may be intermittent.
Wet or rainy days may allow the connection to get wet, and therefore leak electrons from the connection, making the car not start. Also problems where the car stalls after running for a while (for example in the winter) when some snow or ice in the engine compartment melts and moistens the connections.
Another clue is corroded battery terminals. Have you ever seen someone pour soda on their battery terminals to get the car to start? This is the problem.
What do I do if I have a bad electrical connection?
Check and tighten all of the electrical connections. If the cables are damaged, replace them. Make sure the connections are not wet or moist.
If the battery connections are corroded, go ahead and clean the corrosion off the battery terminals.
#3 – A Bad Battery
The battery in a car is a reservoir for electricity. If it cannot hold a charge, or cannot get charged up, then it is going bad. The average car battery lasts for 4 years. It depends on the type of battery and the type of driving.
How will I know if I have a bad car battery?
- Battery will not hold a sufficient charge
A fully charged car battery should hold a charge of 12.6 volts. When the vehicle is running, it should be between 13.5 and 15 volts.
If your car will not start even after the battery has been charged or through a jump start, you may have a bad battery. A good test to check the condition of your battery is to swap it out into another vehicle to eliminate the other factors such as the alternator or starter. If the fully charged battery will not start the other car, then it is the culprit.
What do I do if I have a bad car battery?
If your car battery is bad, take it to an auto parts store and buy a new one. The store will take your old battery and dispose of it properly.
#4 – An Inoperative Alternator
Since the alternator is the part of your car that charges the battery, a bad or inoperative alternator may be the root cause of a dead battery. What I mean to say is that just because you have a dead battery, this does not necessarily mean that the battery is bad. It could just be that it is not being charged up properly. The average lifetime of an alternator is 10 years.
How will I know if my alternator is going bad?
- Dead battery (repeated)
- Electrical problems
- Car stalling
- Grinding or whining sound
- Strange burning smell
- ALT or Check Engine Light
- Ammeter on Zero
Several symptoms of a bad alternator include a dead battery and other electrical problems, such as the radio cutting out or A/C not working. Also, after you charge your battery with an external battery charger, or jump start you car, the car stalls after a while (typically 15-30 minutes or so, depending on how much you charged up the battery). Or the car won’t start again, the next time (repeatedly dead battery).
Alternators tend to go bad all at once, rather than slowly over time, but not always. Another sign of a bad alternator is a grinding or whining sound coming from under the hood, indicating bad bearings, or a voltage regulator that is screaming for more voltage, when the alternator is not producing any.
Other signs could include a strange smell from the alternator belt burning out due to bad bearings (could also be a symptom of a loose belt). If your car as an ammeter, it will not show charging and the ammeter will be pegged at zero. Some vehicles have an ALT light, which indicates that the alternator is not charging sufficiently. Other vehicles may show a check engine light.
What do I do?
If you are experiencing 2 or more of these symptoms, there is a good chance your alternator is bad. Some auto parts stores will check it for you if you bring it in, otherwise, if you are sure it is bad, replace it.
#4 – A Bad Starter
If the battery and alternator are okay, there is a chance that the starter motor and solenoid assembly has gone bad. The average lifetime of a starter is 100,000 miles, but this can vary widely depending on use.
How will I know my starter is going bad?
- The starter does not engage immediately
- You only hear a clicking sound when the key is turned
- A whining noise when you turn the key
- A grinding noise when turning the key
- A jump-start will not start the car
If the battery is fully charged and can hold a charge of 12.6 volts when the car is off, then the battery is probably okay. When you turn the key, if the starter does not engage immediately, or if you only hear a click or clicking, then either a connection is loose, or the starter is bad.
Other symptoms could include a whining noise which would indicate that the starter motor is spinning but not engaging the engine. Grinding indicates poor bearings. If the car won’t start even when being jump-started, the starter may be the issue.
What do I do?
Sometimes giving the starter a whack with a hammer or large wrench will get it to engage (seriously!), but in general, if you have a bad starter, replace it. Here are instructions for replacing the starter in a pickup truck and replacing the starter in a Corolla.
Summary
I hope you found this article helpful! If you know someone having issues with a car that won’t start, please share this article with them!
Thanks for reading,
Rich
Thanks Rich, I find your articles very informative and easy to read/absorb. Very much appreciated.
Regards
Caroline
New South Wales, Australia.