Car Won't Start After Replacing Battery

If your car wouldn’t start, you may have automatically assumed that a dead battery was to blame. So, what do you do when the car won’t start after replacing the battery? It is important to determine what the problem is.

The car battery may not have been installed correctly, or corrosion could cause damage to the connectors. You could also be responsible for a defective starter, or an engine that is stuck. Rarely, though, the ECM or immobilizer might have lost its information and settings.

We look at all of these causes to help you determine what’s going on. The guide will also help you diagnose the issue quickly. 

Causes Car Won’t Start After Replacing Battery

1. Batteries incorrectly installed

If you put a brand-new battery under the hood and it still isn’t powering the car, you need to check the installation. Are the cables in good condition? If not, the battery won’t supply power to start the car. 

Additionally, it’s important for the positive cable to be in good condition, down to where it meets the starter. Also, your vehicle must have a compatible battery. Car batteries aren’t universal. For your vehicle to be able to turn the engine on, it will require a certain size battery and capacity. 

You can’t expect the current used to start a four-cylinder motor to provide enough juice for your heavy-duty pickup truck. If you are unsure what battery you need, check the owner’s manual. 

2. Connector corrosion

The terminal posts and connectors can become corroded over time from battery acid. Hydrogen gases from the battery acid can cause corrosion.

It can cause damage to the connector if it becomes too bad. Sometimes, too much corrosion could prevent the car's starting in extreme situations.

3. Defective Starter

If there is power to the car and the lights turn on, but you can’t get the engine to start, you might have a different problem. It’s possible you diagnosed the dead battery incorrectly.

When you attempt to start your car, a defective starter could make it growl. This can cause no sound or even no sound. 

RELATED: 5 Symptoms of a Bad Starter (& Replacement Cost)

4. Seized Engine

You might also be experiencing engine problems. Think back to the last time the car was running and you might notice some symptoms of an engine that’s failing. 

There could be a burning sensation or smoking. You might also have heard unusual engine sounds like a tapping or knocking. 

RELATED: Symptoms of a Seized Engine & Causes

5. Malfunctioning Alternator

If you were able to get the car started after installing the battery, but it didn’t last long, the alternator might be to blame. Installing the fully charged battery might have given you the power needed to get down the road, but it won’t last if the alternator doesn’t recharge it.

It is a common mistake to replace a battery when it is actually the alternator. That’s why it’s important to properly diagnose the dead battery before making a determination. 

RELATED: 6 Symptoms of a Bad Alternator (& Replacement Cost)

6. ECM Stored Parameters Lost

In some car models, it’s possible that the control modules lose their settings and calibration when you remove the battery cable. However, this should not occur on all car models as the control modules are designed to store information even without the battery.

It is possible, however. To fix the problem you will need to see a mechanic. You could have missing data to your immobilizer.

How to Fix Car Won’t Start After Replacing Battery

1. The Battery

First, check your battery. To ensure that everything is safe, you should first inspect the connections. You also want to verify that there’s no corrosion on the connectors. Use a mix of baking soda and warm water to remove any corrosion. The best result is almost always achieved with this fix. 

A voltmeter can be used to check the condition of the battery if it is the right type and the connections are good. You should see 12.6 volts. If it doesn’t, the battery is dead. You should proceed to the next stage if your battery is brand new.

2. Check the Alternator

There are many people who will be able to help you with an alternator inspection online. Many articles will advise that you unplug your positive connection when the engine is turning. If the car continues running, there’s nothing wrong with the alternator. However, this is a poor way of checking the alternator and it could actually cause damage to the car’s electronics. 

Test the alternator using a voltmeter when the engine is still running. The voltage will rise when you start the engine if there is a full charged battery underneath the car. That’s because the functioning alternator is charging it. If the voltage doesn’t jump or it gets lower, the alternator is on its way out. If you aren’t able to get the car running for a check, take the alternator to your local auto parts store for a free check. 

The cost of replacing an alternator could be between $450 to $700. Most of the cost is for parts. These can range from $400- $550. Labor costs could add between $50 and $150. In most cases, it’s simple to replace the alternator at home.

3. Try the Starter

If all of the interior lights and accessories work, but you can’t get the car running, the starter should be looked at. The starter can have many parts that fail. This includes the solenoid and motor.

Most auto parts shops will give the starter a free test. Just remove it and take it to your local participating location if you aren’t sure how to do this yourself. 

The cost of a starter replacement is between $150 and $700. Starters typically cost $50 to $300. The replacement price could be anywhere from $100 to $400 depending on the location. 

4. Consult a Mechanic

If the above steps haven’t helped you figure out what’s wrong, it’s time to visit a professional. It's possible that you have a more serious problem. You should get an accurate diagnosis.

If your engine has seized up, it will cost you a lot of money to fix. Engine repair and replacement can cost you up to $2,000 

You can get a calibration for around $100 to $300 if the immobilizer or control module has lost its settings.