Have you ever woken up late for work, rushing to get to the car with just enough time to make it to the office? You were proud of yourself until you pushed the start button, and it happened—the slow “wah, wah, wah, click, click” sound of a dead car battery. So much for getting to the office on time, if at all—unless you know what to do when a car battery dies.
What do batteries do in a car?
Car batteries handle many vehicle functions. The car battery is responsible for starting the car and serves as the car’s power bank. It works in concert with the alternator to manage the engine and power the lights, infotainment screen and anything else that requires electricity.
When the engine is off, the battery also provides power to the keyless entry system and alarm. Without a battery, your vehicle is a useless heap of metal and plastic. A battery gives it life.
How do car batteries die?
Although you can usually get four years of work from a battery, they won’t last forever. However, there are some things that can accelerate their demise.
If your headlights don’t shut off when you park for the night, the battery will quickly run down. Likewise, leaving your parking lights or interior lights on for extended periods without the engine running will drain the battery. Take a few seconds to turn off the lights and close the doors when you exit your car.
An alternator charges your battery while the car runs. If it’s faulty, the battery isn’t getting enough power from the alternator. This can cause the battery to deplete faster than expected.
How do you know? If your battery is drained, jump-start the car. If the car continues running, you most likely need a new battery. If the car stops running, it’s probably an issue with your faulty alternator.
Poor maintenance can shorten a battery’s lifespan. For example, suppose the terminals aren’t cleaned regularly and the fluid levels aren’t kept up. In that case, corrosion can form on the battery and prevent it from functioning correctly. A toothbrush, water and baking soda mixture will easily clean the terminals.
Too many short trips
A battery might die if it’s not used often enough or for long enough stretches. When a battery sits for long periods without being charged, the sulfate crystals that form on the plates inside can make conducting electricity difficult. The same thing happens if it’s only used for short trips. If you rarely use your car, consider keeping the battery on a trickle charger.
Another common electrical problem that causes dead batteries is parasitic drain. These happen when a sound system, security system or other accessory continues to use power, even when the car is turned off.
Extreme temperatures can also kill a car battery. When the battery gets too hot or cold, the chemical reactions inside slow down or stop altogether. This can lead to a loss of power and eventually a dead battery.
Car batteries get old. After four years, a battery may have a more challenging time cranking your car. Eventually, they’ll stop working and won’t hold a charge, even if you try to jump-start them.
What to do when a car battery dies
Hopefully you’ll never have to experience the inconvenience of a dead battery. But if your car battery dies, there are a few things you can do to try and revive it.
Try to diagnose the problem
Locate your battery to see if there’s an obvious problem. Depending on how well you’ve maintained the car, there could be corrosion around the battery terminals, a loose or disconnected battery cable or a loose alternator belt. If everything seems in order, you may need a jump.
Get a jump
Suppose you’ve checked out everything and there’s no corrosion, disconnected cables or other apparent problems. In that case, get a jump-start. You’ll need another vehicle to get close enough to reach with jumper cables. Follow these steps.
Make sure both cars are off and the ignition keys are out.
Identify the positive (look for the “P,” “POS” or “+” symbol) and negative terminals (look for the “N,” “NEG” or “-” symbol) on your car battery. Remove any corrosion.
Identify the positive and negative clamps on the cables. The positive charger clamp is red, and the negative charger clamp is black.
Do not allow positive and negative clamps to come into contact with each other.
With both cars off, connect the jumper cables to the appropriate terminals.
First, connect the red clamp to the good battery positive terminal and the black cable to the negative terminal.
Then connect the red clamp to the positive terminal on the dead battery.
Afterwards, connect the black clamp to a clean, unpainted, non-moving metal part. Choose an area on the car’s frame, far away from the battery, carburetor and fuel lines. Never use fuel lines, engine rocker covers or the intake manifold as grounding points.
Start the vehicle with the good battery.
Crank the dead battery car for three to five seconds. If the car has not started after four or five attempts, you probably need a new battery.
Once your car is running, turn the other car off.
Remove the negative (black) clamp followed by the positive (red) clamp from your car. Afterward, do the same with the other car.
Use a portable jumper
Portable jumpers are a time saver, and there’s no need for another person or car. Yours should include instructions for use, which are typically similar to using jumper cables.
One key difference may be that yours calls for attaching the negative cable directly to the negative terminal, rather than somewhere on the frame. Always consult the instructions before attempting to jump your car.
Call a roadside service
Today, many vehicles have warranties that include roadside assistance. Should you hop into your car and find your battery is dead, check your owner’s warranty manual for the number. Insurance companies may also offer roadside assistance with your insurance policy.
If you have no other option, give AAA a call and they’ll jump-start your vehicle. For immediate roadside assistance, you’ll have to pay for basic service and a service fee if you don’t have a membership. But it will be worth it if you need to travel.
What to do if your battery keeps dying
Suppose your battery continues fading and you ruled out user error or other obvious issues. Take your car to a service technician or parts store to test the battery. The technician will use a conductance tester/multimeter to send a small current through one side of the battery and measure it when it comes out the other side. They won’t have to take the battery out, and it doesn’t have to be fully charged. The technician’s device will also determine if your alternator, starter or another issue is the culprit.