Why Your Car’s Battery Light Comes On when Accelerating? (Explained!)

The red battery light lighting up can be worrisome while driving and pushing your car to accelerate.

After all, it should only light for a few seconds and then go off when you start your engine – Is there any danger?

Should you stop the car? Is there anything you can do or do you need to visit an AutoZone?

These are probably some of the questions that may come up in your mind when this red light lights up as you accelerate your car.

So in this post, I go over:

  • The car battery light on acceleration – what it means and why you should pay attention to it
  • How long you should drive with the battery light?
  • Whether Is it safe to drive with the battery light on?
  • What you can do when the battery light comes on as you accelerate

Battery Light on Acceleration problem

During normal car operation, the battery warning light comes on as you start the engine and then goes off after a few seconds.

With this problem, the warning light comes on once your car picks up speed, maybe 2,000 – 3,000 RPM, and goes off when you slow down to lower speeds.

Why Your Car’s Battery Light may Come On when Accelerating?

When the battery light comes on, this is a sign that probably your car’s battery is not being charged anymore – you have a problem with the charging system.

Check our guide for what else can cause your car battery to die quickly

If you consider that it is only happening as your car picks up speed, then it is quite likely that engine power at the higher speeds is not being transferred effectively to the alternator.

Likely causes

A probable reason is that:

  • your car’s serpentine or drive belt is slipping at high RPMs – loose, worn, or does not grip the pulleys as well to drive the alternator to charge your battery as the car accelerates.

  • Belt tensioners not holding the belt tight enough. The belt may slip and not be able to drive the alternator fast enough to generate enough power.
  • Faulty alternator – the voltage and current is no longer high enough to charge the battery

  • Poor cable connections to the battery. The cables do not make clean and firm contact with the battery that makes it fail to charge or to charge slowly.

  • Faulty wiring. Have you changed the alternator recently – was the wiring done properly?

  • Battery drain or bad battery. Is there an unsually high drain on the battery as you drive that causes the voltage to drop?

Should you continue driving – Battery light ON when accelerating

When the battery light on the dashboard lights up as you accelerate the car, slow down and check if the light goes off.

If it goes off, it is likely that your charging system is working at a lower speed.

Regardless of whether it goes off or not, it is wise to only drive up to where your car’s charging system can be checked by a qualified auto technician to avoid the risk of getting stuck because of a flat battery.

Is it Safe to Drive a Car with the Battery light ON?

While you may be tempted to drive on, it is not safe.

The red battery light is a sign that there is a problem with your car’s charging system.

Should you drive on unnecessarily, your run the risk of getting stuck.

Your battery is most probably not charging well and will likely drain sooner or later leaving you no power to start or power the car’s accessories.

How Long Should you Drive with the Battery light ON?

When your car’s battery light comes on and persists, plan to stop as soon as possible at a qualified mechanic’s and have the car’s charging system inspected and rectified to avoid the risk of getting stuck because of lack of battery power.

In the meantime, you should switch off or minimize the use of any of the car’s electrical accessories that can drain the battery – audio system, laptop, and others.

This will help your battery power to last as long as possible until you get your car’s problem fixed.

What to Do- Car Battery Light Comes ON When Accelerating (+fixes)

1. Try to establish if it is intermittent or repeats consistently

When the red battery warning light comes on as you step on the gas, slow down (provided it is safe to do so). Does the light go off?

If it goes off, you may want to accelerate again to see if the light comes ON again.

This serves two purposes – to help you confirm if the battery light comes on only when the car is accelerating, if it is a one-off or an intermittent problem.

This additional information can make a big difference in quickly identifying and solving the problem.

2. Conserve the car battery power

Avoid switching the engine off and then back unnecessarily.

At startup, there is a high power draw on the battery which further greatly reduces the battery charge.

3. Have the car’s charging system checked

Get your car’s charging system checked. You may do this yourself (if you have the skills) or have a qualified car mechanic check it for you.

Check the Battery. Check the battery’s physical condition and its cable connections too.

Are the cables connecting to the battery firm?

Do they make clean contact with the battery terminals?

What is the battery voltage? Is it holding charge? A fully charged car battery’s voltage should be about 12.7 – 12.8V DC.

Fix: If the battery shows signs of damage or is not holding charge, arrange to have it replaced with a good quality OEM recommended battery.

Make sure your battery terminals and cable connections are firm and clean

Loose connections or the fluffy powdery residue around the battery terminals can stop the battery from charging properly.

Check the car alternator’s output voltage

Measure the car alternator’s output voltage with the car engine running and still connected to the battery using a multimeter.

If your multimeter reading is lower or higher than 14.5 – 14.7VDC range, there might be a problem with your alternator.

Note: You can also arrange to have confirmatory and comprehensive tests done on your car’s alternator and battery at an Autozone or qualified auto technician to confirm whether they work well.

If your alternator or battery is not working well, replace them.

You can also check this guide for more information on how to tell if your car has an alternator or battery problem.

Inspect the serpentine (drive) belt

Is it losing and possibly slipping at higher speeds? Does it show signs of wear or cracks?

Fix: If it is loose for whatever reason, have it tensioned.

If it is showing signs of wear, replace it and check if you still have the battery warning light coming on at higher speeds.

Final thoughts

When the battery warning light comes on as you accelerate the car, this is likely a problem with the car’s charging system.

Have your car’s electrical system inspected and the problem rectified so that you do not get stuck with a bad battery.

The areas to look at if you have your battery light coming on as you accelerate the car are a bad alternator, damaged or lose serpentine (drive) belt, loose or poor battery connections, a bad battery, or a parasitic load that is draining your battery’s power.

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