Car Won’t Start with New Battery? Here’s What to Check

Turn the key and all you hear is a click. Or maybe nothing happens. Once again, your car isn’t starting. Luckily, you’ve kept your booster cables out from the last time it occurred, but this kind of frustrating problem prevents you from trusting your vehicle. If you’ve already replaced your battery, it makes the annoyance so much worse yet.

What could be the cause if a new car battery keeps dying? What if a brand new battery doesn’t fix the issue at all? Here’s a list of issues that could be the root of the problem and what you can do about it.

What the battery really does

Most car owners and drivers believe that the battery powers your car’s electronics, modules, and engine while you drive. That might be true to a very small extent, but the main power source while the engine is running is the alternator, delivering electricity on demand while recharging the battery.

A car battery’s main purpose is as a power reserve for when the engine isn’t on. It’s called on every time you crank the engine over, delivering a powerful, high-amperage current to the engine starter to crank it over. And once the key is shut off again but in the accessory or ON position, it continues to power computer modules, the infotainment system, the heater fan, memory and remote functions, and the lights.

So, if you’ve installed a new battery in your car, why would it be dead? Here are some causes to consider.

Check if the battery is properly installed

If you have a new battery but the car won’t start without jump starting it, it looks like a battery problem. Your instinct to replace the battery – or your diagnosis – might’ve been accurate. But if you’ve installed the battery incorrectly, it won’t fix the problem. Check if your battery cables are tight. They shouldn’t be able to move by hand when you wiggle the terminal at the battery posts and, if you can, they need to be re-torqued.

An unfortunate yet common problem is installing the battery cables to the wrong posts. If you install the positive cable to the negative post and the negative cable to the positive post, it’s called reversing the polarity. It can damage the alternator, short the battery, cause wiring to melt, and will almost certainly blow one or more fuses.

Accidently leaving the exterior or interior lights on

For older cars that don’t have automatic lights, it’s easy to leave the headlights, marker lights, or the interior lights on. Sometimes, the light switch gets turned or bumped and you don’t notice the lights on. You’ll have a dead battery, and if you change it, it will start up right away. But if you don’t turn the lights off, you could easily have a dead battery again.

The fix is fast and easy. Fully charge the battery and check to see if there are any lights on. When you turn them off, the electrical draw stops.

Bad Starter

The engine starter is a powerful electric motor, and if it fails, you’ll often only hear a click. Coincidentally, that’s often all you hear when you have a dead battery. A bad starter could mimic a dead battery, and when you change it, it doesn’t fix a bad starter, obviously.

If you’ve already installed a new battery and the car won’t start – just clicks once loudly – it could be the starter motor is faulty.

Blown Fuse or Relay

Sometimes, the problem is so simple that you overlook it. A blown starter fuse or relay could be all that’s causing the issue. It happens when one of the components on the circuit is drawing more power than it should.

Switch the starter relay with another known good one and try again. If it starts, you’ve found the problem. If not, check the starter fuse, again, swapping it with a good one to see if that’s all that’s wrong. But don’t forget, if you have a blown fuse, there’s likely an underlying cause to watch for.

Alternator Problems

replacing alternator

A new battery that won’t hold a charge while you drive almost always indicates a bad alternator. Perhaps the serpentine belt is shredded, or maybe the battery’s been jump started with reversed polarity. An alternator that doesn’t put out any charge or very little current won’t sustain your car’s electronics, let alone recharge the battery.

AutoZone can test your alternator in-store and confirm whether it works or not. And if you need a new one, you’ll be in the right place to pick one up to install it.

Engine Issues

If you’ve replaced your battery but the engine still won’t start, it could actually be an engine problem. A seized engine won’t turn over, and that often resembles a bad starter or dead battery.

If you suspect that your problem stems from an engine issue, it could take hours to diagnose and repair. It might be something you’d like to hand off to a Preferred Shop to help you out.

Parasitic Draw

If you find your new car battery dead after it’s been parked for only a few hours or days, you could have a parasitic draw. That’s when a circuit or electrical part continues to draw power even when it should be turned off. A parasitic draw requires specialized knowledge to trace circuits and identify the underlying problem. Although it might be the root cause, your battery replacement was probably still warranted since fully discharging a battery can reduce its lifespan.

If you’ve got electrical problems that are beyond your purview, we can help. Find an AutoZone Preferred Shop or ask an associate for assistance finding the part and procedure to replace it.

Get batteries, alternators, and everything else you need at AutoZone.

Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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