Last Updated on December 2, 2022 by Bernard Juchli
You want to start a car with a bad alternator if yours is dead. The alternator keeps your car battery charged and if dead, your car won’t start.
A dead alternator is not the end—you could still jumpstart and drive to the nearest mechanic. Sometimes, drivers are tempted to keep jumpstart but this is not healthy for your car. You still need to replace your alternator or even get a mechanic to diagnose the vehicle for other possible problems.
Signs of a bad alternator
There are some relatable signs that your alternator is failing.
Since the starter, alternator, and battery are all interconnected, it could be difficult to identify the precise problem. To pinpoint the precise reason, here are some of the signs of a bad alternator:
1. The vehicle won’t start
An alternator problem might be the cause of your car’s refusal to start and sudden death after a boost. Your vehicle should start after being boosted if your battery is merely dead (but the alternator is still in fine condition).
2. Dim headlights
Your headlights are dimmer than normal, or they fade and brighten erratically. This indicates that your alternator is supplying erratic voltage and might soon fail if proper technical assistance is not offered as soon as possible.
3. The dash displays a warning signal for your battery
The charging mechanism, not only the battery, is represented by the battery light. Make sure your alternator is still consistently providing electricity if it displays on your dash. If an alternator is functioning correctly, it should produce between 13 and 14.5 volts (see the Instructables).
4. Fluctuation in light
When an alternator fails, the accessories in your car will get an unsteady voltage. Your car’s air conditioner pressure might alter, or your headlights could go too bright or too dim. This also applies to the interior lights.
5. Electronics in your car might entirely cease functioning
You could find that a few of your car’s electrical devices have stopped functioning because a bad alternator is unable to provide the necessary quantity of power. Your power window switches, radio, interior lights, etc. may fall under this category.
In the case of low voltage, the majority of modern cars are configured to prioritize vital engine components. While the engine may continue to operate for a short while longer, some optional accessories might not function.
6. Strange sounds are coming from beneath the car’s hood
There may be a problem with the alternator if you notice any new rubbing, grinding, or screeching sounds coming from below the hood.
Start by opening the hood and locating the issue using your senses of sight, hearing, and smell. Many car maintenance problems may be diagnosed if the location is known.
How to start a car with a bad alternator
At this point, it is time to learn how to start a car with a bad alternator. The steps include the following:
1. Turn off the car
Turning off all of the accessories and your car altogether is the first step if you are looking to start a car with a failing alternator. Also ensure you don’t use the air conditioner, headlights, or any other battery-powered electronics.
2. Find another car and cable
Since you will be charging your battery with theirs, get a second car with a strong battery. Additionally, you need a set of jumper cables that will help you in your pursuit of starting a car with a bad alternator.
3. Turn off the accessories
To save all of the battery power available to you, you must switch off every electrical accessory in your vehicle, including the radio, phone charger, GPS, and the air conditioner and heater.
Keep in mind that your car’s computer system and fuel injectors must work together successfully. This implies that only sunlight conditions will allow the jumpstart to function (windshield wipers and headlights will suck too much battery power). You can then start the jumpstart after you’re certain that everything is off.
4. Connect the cables
The jumper cables are made up of a red cable and a black cable, both of which have clamps on the ends. The optimum configuration is to attach the black cable to the negative terminal of both batteries and the red clamp to the positive terminal. A (+) symbol indicates the positive terminal, while a (-) sign indicates the negative terminal.
5. Start the other vehicle
You should start the car with a healthy battery when the jumper cables are connected. Once done, you must then leave the car running for roughly 4-5 minutes. This will assist in giving your dead battery the necessary juice to start your car.
6. Start your car
After you have waited for some time, you can now proceed to start your car. Ideally, the battery will have enough power to provide the alternator with the required voltage. Ensure you wait another 4-5 minutes and try again if the vehicle still won’t start.
7. Get road assistance
If your cars have already started, you must see a mechanic as soon as possible. Meanwhile, your car won’t operate for very long, and the pressure put on the battery and actuator will eventually cause serious damage.
Avoid any routes with high-speed traffic and stick to roads with slow and low volumes of traffic since there is only a certain amount of time until the car shuts down again.
Unless it’s midnight or required, turn off your headlights. Close the A/C and any operating music players or radios.
How long can I drive with a bad alternator?
The amount of charge the battery had before the alternator failed, the number of accessories you have operating inside the vehicle, and the road conditions all affect how long you have until the car shuts off.
The power drain may occur relatively fast in modern automobiles since many of its components, including power steering, cooling fans for the engines, and other systems, are powered by electricity.
Your best option is to acquire a new alternator right away and install it or go to a repair shop as soon as you can to get it changed.
Risk of driving with a bad alternator
When driving with a damaged alternator, there are various possible safety risks. The biggest problem is that most modern vehicles have electrically assisted power steering, which increases the steering effort significantly when the power fails.
At highway speeds, this might be quite dangerous, particularly for new drivers or while traveling through an area with plenty of turns.
Additionally, because entirely emptying a battery shortens its useful life, you’ll be doing your battery no favors. Your vehicle can stall and leave you trapped in traffic if your alternator has failed and the battery is low on charge.
You can certainly start a car even with a bad alternator; the only thing needed for you to do is jumpstart the vehicle. In the same vein, your car will likely turn off after some minutes if you do not get to a mechanic as soon as possible.
It is important to be aware that you shouldn’t wait until your car stops in the middle of the road before seeking the help of a technician.