Your vehicle’s battery is like its heart: Without it, your vehicle doesn’t have the power to start, move, or do anything else. So it’s important to understand at least a little bit about your battery and to know the most common signs that it needs to be replaced.
Signs Your Car Battery’s Dead or About to Die
- Your engine cranks, but it doesn’t start.
- Your engine doesn’t crank or start, and the lights don’t come on!
- One day it starts fine, then the next day it won’t start at all.
- Cold cranking is hard work.
- You’ve jumped it a lot already.
Each of these scenarios will be thoroughly discussed below.
1. Engine Cranks, but Doesn’t Start
If your engine cranks or turns over when you turn the key, but it won’t start, I say the most likely culprit is your battery. It might be your starter, it might be something else, but 94% of the time, it’s really your battery, even if the car is cranking fairly vigorously. Even if an ammeter (current-measuring device) says the battery is good, it can still be a few volts shy of what your vehicle needs to run efficiently.
When you find yourself with a car that won’t crank hard enough to start, you’ll want to use jumper cables or a jump-starter box to get it running again
Once your car is running again, disconnect the cable, then let your engine run for 30 minutes so that your alternator can charge up your battery again.
After that half-hour, when you are stopped at home or in a safe place, do a little test. After you turn the engine off, wait at least a minute, then start it again. Wait another minute and start it another time or two to make sure that you won’t be stranded at the gas station or wherever you go next.
Note: At this point, most batteries will have charged themselves up from the running of the alternator and be fine for a day or two. Do not take that time for granted. Use it to hunt down a new battery and replace the old one before you end up stuck in the middle of nowhere.
2. No Crank, No Start, No Lights
This situation is pretty straightforward to diagnose, and it’s an even stronger indication that your battery is at fault. Your battery powers all the accessories and lights in your car, especially when the alternator is not running. So, if your car just seems to be completely void of all signs of life, then your battery is the first thing you should be looking at.
And be aware that in this situation, where your vehicle doesn’t even have the juice to work the lights or turn over the engine, it could be a combination problem involving your alternator as well.
If the car won’t crank or start but the headlights do work, that may indicate a more interesting problem, maybe the starter or a mechanical problem in the engine.
3. One Day It Starts Fine, the Next Day It Won’t
If starting is an intermittent problem for you, it’s a sign that either your battery terminals are loose, broken, corroded, or calcified or that you have a parasitic draw (your power is being drained by some gizmo that’s on when it’s supposed to be off, or by some wire that’s touching something it shouldn’t).
- Check out the battery cables first, as they are usually the prime suspect and are easier to check yourself.
- Make sure the cables fit firmly and securely on the battery posts. There should be zero play in them. You shouldn’t be able to wiggle them even an inch when they are tight. Also, make sure that the cables going to the terminals are not frayed or falling apart; if they are, replace them as soon as possible.
Parasitic draws from sources other than the battery cables are fairly common. Suspect a parasitic draw if the car starts right up if you drive it several days in a row, but then fails to start if you let it sit for a day. To investigate parasitic draw issues, see your favorite mechanic, or look at the last section of this article, and get ready to have fun with an ammeter or voltmeter, as these are the tools you’ll need to check your alternator, accessory lights, fuses, radio, alarm, and all other components that might be draining your battery in secret.
4. Cold Cranking Is Hard Work
If you look at your battery, somewhere on it you should find a label stating a number for “Cold Cranking Amps.” Those amps are responsible for giving your engine enough energy to get started the first time of the day, generally referred to as “cold cranking.”
Thus it’s not surprising that an early sign that your battery is running out of life—a sign most people miss—is that you are regularly putting extra energy into starting the vehicle. You know what I’m talking about. You get in your car, you tap the gas pedal, you turn the key a few times, and all you get for the first few minutes is lots of weak rotations of the engine. After you’ve all but decided the car is going to make you late for work, it suddenly starts up and sustains an idle.
Now, what I mean by “regularly” is having to do this more than three times per week. That would be a sign that your battery is giving notice and getting ready to retire.
But, keep in mind that if it’s really cold out, it’s fairly normal for your vehicle to hang back and start only with difficulty. Not only is gas hard to vaporize and oil gooey when it’s cold, but batteries put out only half their normal power when the temperature is 0˚F (and only a third of their power when it’s 32˚F). So in the cold, you may have to be patient. But, if your car doesn’t go back to a reliable “cold” crank when the weather warms up, you’ll want to get a new battery within the next three months.