Car Won't Start With a New Battery

Even the highest-quality car battery still only has a limited lifespan of 3 to 5 years. You get to a point where the headlights are dim, the car struggles to turn over or clicks when you turn the key, and you know it’s time to say goodbye to an old friend.

You’ll have to bite the bullet, sinking money in a new car battery and lamenting the fact that you’ll have to reprogram all your radio stations. The new battery goes in, you turn the key, and the car still doesn’t start. This can be as frustrating as it is worrying, as this is supposed to be a simple fix.

If you’re lucky, it’s something easy to fix, like a loose ground wire or the new battery wasn’t charged when it was at the store. However, a more significant problem, such as a bad starter or an alternator issue, might need a mechanic to fix.

To find out why your car isn’t starting despite having a brand-new battery installed, we will have to consider some of the other symptoms the car might have been giving you and the potential faults behind them.

Testing a Battery

How to Test a Car Battery with a Multimeter

Before you recycle your old battery without question, could you take a moment to have it tested? You can bring the battery to an auto parts store or a battery specialty store. They’ll usually test it for free, hoping you’ll buy your new battery from them.

If you can’t get to a battery or auto parts store, you can quickly test your own battery at home with a multimeter. You set it to read voltage, then touch the black lead to the battery’s black (Negative) terminal and the red lead to the red (Positive) terminal.

When the engine is off, you should get a reading of around 12.5 Volts. If the engine runs, you might get a reading within 1 volt +/- of 10 volts.

This is a good practice for determining if your old battery is truly bought on the farm. It’s also wise to do with a new battery to ensure you didn’t get a defective one. The results might even help you later when you’re troubleshooting why your car won’t start even with a new battery.

9 Reasons Why Your Car Won’t Start After a Battery Replacement and How to Get Going

Some of the most common reasons why a car won’t start even with a new battery are starter problems, a loose ground wire, installation issues, or even a manufacturer’s defect in the battery itself. Problems with the ignition switch, serpentine belt issues, or an alternator problem could also lurk in your engine bay.

To help you dial in on what the problem is, we’ll start with the more likely candidates and things that are easiest to fix. Through this basic process of elimination, you can dial in the precise reason or reasons that your car won’t start despite having a new battery.

1. Improper Battery Installation

Improper Installation

Battery cables need to be clean and tight in order for the battery to transfer enough charge to turn the starter motor and start the engine. If you put the new battery in yourself and there was corrosion on the connectors from the old battery or the fastening hardware wasn’t rock solid tight, your car might not start.

How to Fix

Give the battery a good once over, ensuring all the connections are clean and solidly clamped down on the terminals. Even the slightest amount of play in either the red or black battery connections can hamper its ability to turn over the engine.

Also, check to ensure the top locking bracket at the top of the battery holds it firmly on the plate. If the battery is loose, it could affect the connections.

2. Problems With The Engine Control Unit (ECU) Can Prevent The Car From Starting

ECU Needs to Be Reset

With some newer cars, the ECU needs to be reset after the battery is replaced for the engine to start properly. When this happens, you’ll usually get a check engine light when you have the key in the ON position. This might be a simple matter of the ECU not communicating with one of the control modules responsible for some part of the ignition process.

How to Fix

How To Reset All ECU’s and Control Modules in your Car or Truck

Resetting the ECU is relatively straightforward, but some models have their own specific method for doing so listed in the owner’s manual or repair guide.

  • Step One: Loosen the black (Negative Wire) and cover the negative terminal with a rag or a wood block to isolate it.
  • Step Two: Connect one jumper cable end to the black lead and connect the other end to the battery’s red (Positive) terminal. This allows the battery to access the ground wire connection while isolating the black terminal from the circuit to drain all the ambient charge from the ECU and the control modules.
  • Step Three: Wait at least 15 to 20 minutes for the ambient charge to drain.
  • Step Four: Reconnect the black (Negative) ground wire to the black terminal on the battery.
  • Step Five: Put the key in the ignition and turn it to the ON position without actually cranking the engine to start it.
  • Step Six: Wait 10 to 15 seconds. This will let the ECU connect with the control modules to coordinate all the updated values in their respective systems.
  • Step Seven: Turn the key back. Wait 10 seconds. Then turn the key to start the car and let it run for 5 minutes in neutral or park.
  • Step Eight: Take it for a test drive. Turn the car off, wait an hour, and check to ensure the car starts with the new battery again.

3. Ensure That All Ground Wires Are Securely Connected

Check for a Loose Ground Wire


If the black (Negative) wire connected from the new battery to the block ground or frame of the car is loose, the circuit won’t close, and the starter and spark plugs won’t get the voltage they need to start the engine. You might even get a weak start or two early on, but the poor ground connection makes it hard for the alternator to keep the new battery charged.   

How to Test

Test Truck Ground And Power Wire With (TEST LIGHT)

It’s relatively easy to test if the bad ground is preventing your new battery from starting the engine. It just takes a test light tool and a few seconds.

  • Step One: Connect the test light to the black negative terminal of the battery. Then, touch the probe leading to the red terminal.

The test light should come on, indicating that the battery at least has some charge.

  • Step Two: Take the test light connection off the black terminal and connect it to the red positive battery terminal.
  • Step Three: Touch the probe to the metal of the engine block.

It should come on and stay on. If it flickers or doesn’t work, it’s strongly suggesting that there’s a ground issue.

  • Step Four: Move the test light back to the black negative terminal of your new battery. Use an alligator clip or some tape to connect the probe end to the metal of the engine block.
  • Step Five: Have someone else turn the ignition key.

If the light comes on, it means the electricity flows through the block, and the starter returns to the battery’s negative terminal, as the meager test light offers up a better path than the loose ground connection.

How to Fix

Finding the loose ground calls for tracing the black wire from the battery’s negative terminal to the point where it’s bolted onto the chassis frame of the car. In some models, this is easy, but in some, you feel like a spelunker exploring the unknown depths of a mysterious cave.

When you do find it, the black wire should have a rock-solid connection to the bolt on the frame. There shouldn’t be any rust, loose wires, or connections. In some vehicles, a “Ground Strap” looks like braided copper wire wrapped around part of the engine transmission.  

If you do find a problem, you might need to unbolt the ground connection. Then, clean away any rust or corrosion with WD40 and automotive-grade metal sandpaper. Then, resecure it in place and tighten down the nuts until they are rock solid.

If this is outside your depth, or there’s a significant amount of rust on the chassis frame, then you’ll need a mechanic to fix it. The parts cost is usually pretty low, and it’s a matter of paying for the labor.

A mechanic fixing the loose ground wire might only cost you $80 to $120.

If the mechanic has to weld or repair severe rust around the ground wire, the cost might increase from $220 to $350. Depending on the severity of the problem.  

4. Cold Weather And Parasitic Draw Is Making It Harder To Start The Engine

Cold Weather And Parasitic Draw

Deeply cold weather, which hampers the electrochemical processes inside a battery and/or parasitic draw from electronic devices, can sometimes combine to prevent even a new, strong battery from starting a car. This is even more likely to happen if the car sat for several days in cold weather and you left a dome light, phone charger, or other electronics on.

In such a case, the dome light might come on, and the radio might even play. Yet when you turn the key to crank the engine, the lights dim, it churns a few times and then clicks as the battery finally goes flat.

How to Fix

If your car has been parked in subzero weather, you can start the engine again with a simple jump start. Let it idle for a few minutes to warm up the engine oil. Then take it for a good long drive at highway speed. This will help recharge the battery.

When you park it, ensure all electronic devices are turned off, and car phone chargers are unplugged. If the forecast calls for severely cold weather, and you have a block heater, plug the car in.

This won’t do anything to charge the battery itself, but it will keep the engine oil and other essential components warm, which will make the car easier to start again later. Then, make sure to start your car and run it for at least 10 minutes every day.

5. The Starter Relay Or Fuse May Be Faulty

A Bad Starter Relay/Fuse

If your starter relay is bad or blew due during the battery install, it won’t be able to receive a charge from the new battery at all. If this is the case, you might hear a click when you turn the key, but the starter itself doesn’t engage at all, and you won’t hear any cranking sound.

How to Test

How To Test and Replace A Starter Relay

The easiest way to test if a bad starter relay is preventing your new battery from starting the car is to find the specific relay and replace it. It will be in the engine bay’s fuse/relay box, a black box usually found on the driver’s side near the firewall. However, some cars put the starter relay in the interior fuse box.

You can check your owner’s manual or the repair guide to locate the box and which relay runs the starter. If you’re lucky, your starter relay is a big fuse, and you’ll be able to see if it’s burned out. Usually, it’s a little black cube with four or perhaps five metal prongs holding it into the box.

You can test the prongs with a multi-meter set to Ohms. There’s a little bit of trial and error, but as you touch different combinations of prongs, a good starter relay will make a clicking sound, and you’ll get a reading around 5 Ohms.

How to Fix

Fixing a bad starter relay is as easy as replacing the old one.

The part itself usually costs less than $50, and you pop it in.

If you can’t find your starter relay, or you feel like you’re out of your depth, a mechanic will charge you another $35 to $50 in labor for a final cost of $85 to $100.

The concern here is what caused the starter relay to burn out. An accidental short while installing the new battery makes sense. However, if it happens again, chances are good that you have some wiring short leading to the starter that needs to be repaired.

6. A Worn-Out Or Damaged Starter Motor Isn’t Engaging Properly

A Bad Starter

A failing starter motor that was hidden by the old bad battery can be exposed when you install a new battery, only to find that the engine still struggles to turn over. In a case like this, one or more of the teeth on the starter’s Bendix gear often fail to connect with the flywheel when you try to start the car.

Sometimes, the good teeth on the gear match up, and the car starts fine. Then, other times, the worn teeth don’t match up, and the starter clicks or the car cranks away, draining the new battery without starting.

However, it might also be possible that the solenoid in the starter that engages the process is stuck. This will give you a click, and the engine will do nothing.

How to Test

If the engine clicks without trying to crank, take the lug wrench that comes with the car or a hobby hammer and tap the upper part of the starter half a dozen times. This is where the solenoid is, and sometimes, the contact and vibration will get it to release. Then, try to start the car again. If it turns over like normal, then the starter’s solenoid is having an issue and will likely need to be replaced soon.

If it’s a failure in the Bendix gear and the car has times when it starts normally, then other times when it cranks without starting or cranks for a long time before it starts weakly, the starter will also need to be replaced.

Most auto parts stores and service centers can check your starter for you for free, which will help rule it out as the reason why your car isn’t starting with a new battery or confirm that it’s the true culprit.

How to Fix

AutoZone Car Care: How to Replace Your Starter

These days, it tends to be more cost-effective to replace your starter rather than rebuild it. Especially if you’re a reasonably capable DIY mechanic who can handle the replacement cost; however, even if you bring the starter to a reputable mechanic, they’ll tell you the cost of a complete replacement makes more sense.

The cost of a mechanic replacing a starter motor ranges from $150 to $400, with the real-world average landing around $300.

Approximately half of this cost is the part, and half is the labor.

7. A Failing Alternator Can Lead To A Dead Battery Even After Replacement

A Failing Alternator

If you put a new battery in your car and it started properly the first few times but then died or won’t start at all, you might have an alternator problem. The alternator charges the battery and is driven by the serpentine belt, which is powered by the engine’s rotation. If the alternator goes out or starts failing, it won’t be able to replenish the battery’s charge.

This state of diminishing return eventually leaves you with a battery that’s too low to turn the engine over or completely flat. It might try to crank at first. It gets slower and slower until it just clicks.

Testing for a Bad Alternator

How to Test an Alternator

If the alternator’s internal brushes, voltage regulator, or other internal components are worn out, the serpentine belt can turn the alternator pulley uselessly. The alternator won’t be able to deliver a proper charge to the battery.

This usually shows up as a red battery warning light on the dash. You’ll probably also notice your headlights and internal lights are going dim. You might even be able to jump-start the car to get the engine running, only to have the engine stall out a few moments later.

You can quickly test your alternator by connecting it to a multi-meter set to measure voltage. If you’re getting 1 to 2 volts less than 12.5, then chances are good you have a failing alternator.

If you don’t have a multimeter, most auto parts stores will test your alternator for you for free. However, they might need you to take the alternator out so they can properly bench-test it.  

How to Fix

If a bad alternator is the reason your new battery can’t start your car, you’re faced with two options. You can either rebuild it or replace it. 10 or 15 years ago, a hungry mechanic would probably advocate rebuilding it. However, today, the cost to have a mechanic rebuild or replace the alternator is very similar.

However, the average DIY home mechanic usually doesn’t have the skills to rebuild a bad alternator. At the same time, a reasonably capable DIY mechanic can usually remove the old alternator and install a brand-spanking new one for less than $125 in parts cost.

If this is beyond your skills, there’s no shame in having a mechanic replace it for you. However, you’ll likely be looking at another $125 to $150 in labor costs.

8. A Bad Serpentine Belt Can Cause The Battery Not To Charge

A Bad Serpentine Belt

A slipping or bad serpentine belt could fail to power the alternator, gradually leading to insufficient battery power necessary to start the car. In a case like this, the alternator might be perfectly fine, but the serpentine belt is slipping over the pulley.

As the belt starts to fail, you might notice a screeching sound when you start the engine or if you step down hard on the accelerator. You might also notice the engine running hot and other belt-driven components like the air conditioning seem unpowered or won’t work at all.

How to Test for a Bad Serpentine Belt

How to Tell if Your Car Needs a New Belt (Before It Damages Your Car)

Start by inspecting your serpentine belt for cracks and signs of wear and tear. However, this is only the case with serpentine belts made from reinforced rubber.

If you have a newer EPDM serpentine belt, there might not be any obvious physical signs of wear and tear. To determine if it’s the culprit, you’ll need to test it with the belt is bad is to use a wear gauge and the following steps.

  • Step One: Turn the engine off and let it cool completely.
  • Step Two: Set the belt wear gauge on the serpentine belt so that the ribs on the underside of the belt fit perfectly with the corresponding contours of the belt gauge. 
  • Step Three: Make sure the belt gauge is thoroughly seated, apply light pressure, and try to rock the gauge back and forth.
  • Step Four: Observe the gauge for 10 to 15 seconds.

How to Fix a Bad Serpentine Belt

How to Replace a Serpentine Belt

Fixing a bad serpentine belt calls for a total replacement and retightening of the tensioner pulley. Once you’ve sourced the correct replacement belt, you can remove the old one and install the new one via the following steps.

  • Step One: Take a picture of the worn-out serpentine belt’s placement and draw a reference picture in case you need it.
  • Step Two: Find the primary bolt on the tension arm pulley and gently loosen it. You might need to use a breaker bar or a belt tensioner tool.
  • Step Three: Put on a pair of gloves and gently move the serpentine belt off the pulleys without stressing out any of the pulleys on the belt-driven engine components.
  • Step Four: Inspect each of the pulleys, with extra attention on the alternator pulley. Look for signs of alignment problems or excess wear and tear that might have accelerated the death of the serpentine belt.
  • Step Five: Carefully thread the serpentine belt onto the primary tensioner pulley and then over all the other component pulleys. Check the reference photo to ensure you are threading it over and under all the correct positions.
  • Step Six: Give all the pulleys a once-over to make sure the replacement serpentine belt is appropriately centered on each one.
  • Step Seven: Adjust the tensioner arm with the correct level of tension.

9. A Faulty Ignition Switch Might Be The Culprit

A Faulty Ignition Switch

A faulty ignition switch that might have gone undetected with your old battery could be the secret reason why your car isn’t starting even with a new battery. The ignition switch works in tandem with the ignition lock cylinder to both start the car and keep it running. Keyless cars have something similar in the form of push buttons, rockers, or rotary switches.

A faulty ignition switch is one of those things that goes slowly over time. So, it can happen as your old battery was on its way out, and you mistook it as just being a battery problem. It can sometimes mimic an alternator issue as the car can stall and not restart again, or you notice issues with electrical accessories.

How to Test

no start / crank : troubleshoot the ignition switch

You must first take the shroud off the steering column to test a potentially faulty ignition switch. Check the repair manual for your make and model to make sure you don’t damage any of the retainer clips when doing this.

Once you can access the steering column’s guts, find the ignition switch. It should be right below the steering wheel near the keyhole for the ignition cylinder lock. You can then test it with the following steps.

  • Step One: Set a multimeter to the 20 Volt DC setting.
  • Step Two: Touch the black probe to a grounded piece of metal on the car.
  • Step Three: Touch the red probe on the metal connectors on the ignition switch.
  • Step Four: Turn the key to the “Run” position without actually trying to start the engine. Then, check the multimeter.

If you get a reading around 12 Volts, the ignition switch is good. If you get a reading below 10 volts, either the ignition switch is bad or your new battery isn’t charging.

How to Fix

How to Replace Ignition Switch in Your Car

If you have an older car or don’t have an electronic security system linked to the ignition, you can simply swap out the bad ignition switch. This is usually beyond what a DIY mechanic can safely handle, as you risk accidentally setting off the airbag.

It’s also quite technical, so if you make a mistake anywhere in the process, you’re setting yourself back even more on the cost of having a mechanic fix it correctly the first time.

The part cost for a new ignition switch ranges from $95 to $150.

The labor cost to have a mechanic install a new ignition switch will add another $75 to $125 to the final bill.

If your car has the ignition switch tied to the onboard security system, the mechanic might need to replace it entirely and might need to spend extra time changing the key or updating the car’s computer.

This can add another $75 to $125 to the final bill.

Frequently Asked Questions

Can a New Car Battery Be Defective?

While it’s rare, there are times when a new car battery is simply defective. This is usually a manufacturer’s defect inside the battery itself. A problem like this is more likely to occur in a sophisticated lithium-ion battery rather than a rudimentary lead-acid car battery.

Can Cold Weather Kill a New Battery?

The chemical electrolysis effect inside a new lead-acid battery is hampered by the cold, thus making it harder to store a change. Though this doesn’t “Kill” the battery, it can be brought back to life with a jump start and a good long drive on the highway.

Lithium-ion car batteries, though, are more sensitive in deep cold temperatures. In the deep cold, the internal lithium plating charges could cause an internal short of the battery and a failure.

Can Hot Weather Kill a New Battery?

Prolonged hot weather can accelerate the chemical processes inside a lead-acid car battery, gradually shortening its life. This can potentially kill a car battery three years or older. However, heat won’t kill a new battery without some other fault or defect.

When the New Battery Isn’t Enough

Improper installation or a loose ground wire are two of the more common and inexpensive reasons a car won’t start with a new battery. This is even more likely to happen if you installed the battery yourself, and/or some corrosion issues might be at play.

If you didn’t test your old battery before installing it, and your new battery still has the car starting hard or failing to start, you might have a bad starter, a dying alternator, or a bad starter relay. If it’s the relay, the car won’t turn out, and you’ll get a clicking noise when you turn the key. If it’s the starter itself, you might hear a little cranking, but the car won’t turn over to start the engine fully.

If the car started fine when you installed the new battery but wouldn’t start the next day or two later, you should suspect a bad alternator. While checking out the alternator, also take a moment to test the serpentine belt. If either of them isn’t in good working order, the alternator won’t be able to recharge the battery sufficiently. It will keep depleting the battery, so it won’t turn over.

Jason Farrell

Written By

Jason Farrell

Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.

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