Do You Have To Replace Battery When Replacing Alternator?

Key Points:

  • It is not obviously required to change the battery when replacing the alternator.
  • If the battery can’t work anymore, only then the battery needs to be replaced.

When the alternator goes bad, you need to replace it immediately. However, there’s a popular myth of changing the battery as well while replacing the alternator. But do you need to replace battery when replacing alternator?

Well, it is not necessary to change the car battery while replacing an alternator. However, it is also common that an old battery fails when an alternator goes bad. So, the best thing is to retest the battery after being fully charged. It typically takes about 20 to 40 minutes of driving to recharge a car battery.

If you’re perplexed about whether to change the battery with the alternator, this writing would be helpful as it discusses when to change the battery of the car.

Determining If You Should Change Battery When Replacing the Alternator?

The battery in your car stores the electric power to start its engine. Again, an alternator recharges the battery while the engine is running. So, the alternator is the most important part of the charging system. However, alternators fail as a result of long usage and aging. Also, fluid leaking is the most common cause to turn an alternator bad. 

If the alternator is needed to be replaced, you may sometimes need to change the battery as well. It largely depends on why you are replacing the alternator. The best way to be sure is to take a test of the battery. The battery should undergo a load test to be tested its capacity and capability.

The load test is a simple and easy process. It actually checks if there are any bad cells and how many cranking amperes of capacity is stored in the battery. However, make sure to test the battery from an experienced professional who has a high-quality load tester device.

This is because, if the tester is problematic, it may fail a good battery by simply turning on a secondary load, for example, the headlights. The report from the test then reveals that the battery is failing while it was completely in order. Another possible reason to fail the battery is not knowing the minimum and maximum operating limit which is instructed in the owner’s manual of the car.

If your car starts and runs perfectly with the replaced alternator, I’d recommend leaving the battery alone. However, if the battery is more than 5 years old, you may not want to take any risk with it during the first winter. So, get it replaced.

If the battery is less than 3 years old, chances are it still has a warranty to be replaced with a new one from where you bought the battery.

Do I have to charge the battery after replacing alternator?

Yes, most certainly you have to charge the battery after replacing the alternator. Once the battery is fully charged, it should be load tested to determine if it is still good or not. If your car starts perfectly, you don’t need to change the battery at all.

Can a bad alternator ruin a new battery?

Yes, a bad alternator affects the lifespan of the battery severely. A failing alternator may overcharge or undercharge the battery. It kills the battery by leaving it overheated or flat dead. In both cases, the battery just accelerates towards its failure.

Frequently Asked Questions (FAQs):

How Do I Know If I Need A New Battery Vs Alternator?

To determine if you need a new battery or alternator, you need to look for some symptoms at first. If you feel any trouble while starting or if the engine doesn’t start at all, dim lights, or if you face problems with stereo system output, probably you need a new battery. Again, if the car starts but stalls frequently while underway, chances are, the battery isn’t being recharged because of a faulty battery.

Why Doesn’t My New Alternator Charge My Battery?

The most common reason why a new alternator doesn’t charge the battery is that the battery may not be charged fully. When an alternator goes bad, it doesn’t charge the battery while underway. So, you need to make sure the battery is fully charged even after the alternator is replaced. You can use a voltmeter to check the current coming from the battery.

Do I Need To Replace The Battery After Replacing Alternator?

No, you don’t necessarily need to change the battery after changing the alternator. The battery needs to be replaced only when it doesn’t work efficiently.

Final Words

So, do you have to replace the battery when replacing the alternator?

The answer is negative and I recommend a load test instantly after replacing the alternator. Then, if you need to change the battery even, you’ll certainly know it and replace it with a new one.

Also, always check back if the battery has a warranty left or not. If it still backs you up with a warranty period, you can easily change it with a new one without spending bucks even.

Happy Motoring!

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