4 Reasons Why Your Car Battery Won’t Hold a Charge

Knowing how to jump start a car battery is a good skill to have—but what happens when it’s not enough? Most of the time when your car won’t start, you assume it’s because of a battery problem. So pull out the jumper cables, jump start it, and go on your way.

But what do you do if the same problem occurs the next time you get in the car?

Reasons Why a Car Battery Won't Hold a Charge

When your car battery fails to hold a charge, it can be frustrating and leave you stranded at the most inconvenient times so it’s essential to find out why. Several factors could be responsible for a battery that keeps losing its charge. Here’s a quick rundown of four of the most common causes of a battery that won’t hold a charge:

1. You Left Your Lights or an Accessory On

It's not uncommon for drivers to leave their headlights on, only to discover that their cars won't start. Besides lights, other accessories that can drain your battery are:

• Any electronics, including your radio and entertainment systems
• Your car's air conditioner or heating system
• Alarm systems
• Leaving power windows partially open
• Defrosters and heated mirrors

Typically, these issues only require a quick jump-start for you to start driving again.

2. Your Battery Isn't Getting Recharged

As you drive your car, your vehicle's alternator works hard to generate electrical power to recharge your battery. However, a mechanical charging problem like a faulty alternator can mean your car won't hold a charge. Cracking or fraying in your alternator cables is a clear sign something's off.

Instead of completely replacing your alternator, you may have a smaller issue, such as a broken or slipping belt.

3. There's a Parasitic Electrical Drain

Besides a bad alternator being a culprit, any number of parts or devices can be a parasitic electrical drain for your battery. The problem can be as simple as a cigarette lighter or a certain light drawing too much power. 

If your battery quickly dies for no reason, it's best to have a mechanic take a look. Additionally, when asking if a bad starter can drain a battery, the answer is yes.

4. You Need a New Battery

Car batteries don't last forever---if your car battery won't hold a charge, it might be time for a replacement. Corrosion is generally a good indicator, but a professional can also determine if you need a new battery if you're running into charging issues.

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How to Diagnose a Car Battery Charging Issue

While there are multiple causes of a failed charge, you might wonder how to determine exactly which one is to blame. Perform the following tests to find out:

• The first thing to do is try to turn on your headlights. If they come on with their normal brightness, your problem is probably a bad starter or poor wiring—not the battery. If the lights do not come on at all, or if they’re dimmer than normal, then the problem is more likely with the battery.
• To test the voltage of your battery, get a voltmeter and connect the red lead to the positive terminal and the black lead to the negative terminal. Hopefully, you’ll get a reading of over 12.6 volts, showing a fully charged battery. If you don’t, there’s definitely an issue with the battery being poorly charged.
• Does the battery look obviously corroded or worn out? Is it more than four years old? If so, the simplest solution may be to have the battery replaced.

Even if you believe you’ve discovered the exact problem, you may want an expert opinion. Buying a new battery when the alternator is the real problem—or vice versa—will prove highly frustrating when you end up spending more money than necessary.

If you're unsure of the cause, it's best to bring your car to a local car care center for a thorough inspection, where our technicians can accurately diagnose the issue and determine whether a car battery replacement or other repairs are needed.