What Does ‘Check Charging System’ Light Mean?

Have you ever seen a red warning light on your dashboard that looks like a car battery? Or, as some call it, a robot head that is winking. On most vehicles, it will stay on for a few brief moments after you have started your car, which is normal.

However, it is not that simple if it stays on for more than several seconds, or it comes on in random intervals while driving. On some cars, this might come together with messages such as ‘check charging system’ on your dashboard or on-board computer.

This article will help you understand how the charging system in your car works, ways to spot symptoms of upcoming problems, and make your car more reliable.

What does check charging system light mean.

Can I Drive With a Faulty Charging System?

As you may imagine, starting a car requires the largest amount of electricity. The starter motor must turn many parts, such as pistons and similar heavy parts, for several times until the engine is running. And while you may think once the engine is running, you are on the safe side even if the charging system is not in perfect shape, it is more complex than that.

Many essential systems in your car need a steady current flow so they can work properly. Things like headlights or windscreen wipers are just one of them. And even if the day is sunny and bright, you still need electrical power for spark plugs and various on-board computers that keep your car running.

Because of this, driving a car that has issues with a charging system is not a good idea and can cause additional damage. In case there is a charging system warning light or message on your dashboard, start looking for a suitable place to pull over. Ignoring an error within a charging system may leave you stranded by the side of the road. 

How a Car Charging System Works

The battery, which stores a large amount of electrical power, has one major job. This is to provide power that drives the starter motor when you turn the ignition key.

Once the engine in your car is running, the alternator makes sure that there is enough electricity. This is a simple device, similar to a dynamo on a bike, that uses engine rotation to produce electrical power. In most cases, the alternator is bolted to the engine block and connects to it with a serpentine belt.

As the engine works, it spins the alternator which produces an electrical current. A network of wires then transmits this current to the battery at one side and various consumers on the other side. This may be things like lights, ignition coils or wipers.   

If you were to open your alternator, you would find a rotor with a series of magnets with alternating north-south pole directions that placed around it. Sitting in front and rear bearing, the rotor spins inside a stationary core that surrounds it. You can think of this is as a set of densely knit copper wires. When a magnet passes over a conductive wire, it creates an electric current. With so many magnets and wires, the alternator can produce a high charge event at idle. Still, the alternating current it creates is in the wrong format, as your car needs direct current.

To convert it, there is a set of diodes that stop the current from alternating by forcing it in one direction. In the end, as the alternator makes more voltage than the battery can handle, a voltage regulator stands between the diodes and the battery to determine how much electricity passes.

the Symptoms of Charging Issues

Besides the obvious, which is a ‘check charging’ warning light that stays on, there are several other symptoms that could point towards problems with the charging system of your car:

  • One of them is a weak or dead battery. Because of this, the starter motor will not engage when you turn the key, or it will turn slower than usual.
  • Sometimes you could notice that the headlights and interior lights appear dim or change their intensity when you rev up the engine.
  • You may also hear grinding and squealing noises coming from under the hood. The cause of these sounds can be within a failing alternator or a loose serpentine belt slipping over alternator pulley.

Why Do Alternators Fail?

The alternator in your car lives under harsh conditions. For starts, it rotates all the time while the engine is running, which makes it prone to mechanical wear and fatigue. The most common failure points are bearings and damaged rotors, which can stop the alternator from spinning.

In addition, if there are any issues with electronic components like a controller or diodes, the alternator will not produce enough electricity despite spinning fast enough. And being so close to the engine doesn’t do much favor to the alternator, either. While heat exposure on its own is not a big problem, any coolant or oil leaks that trickle over electrical components will only speed up deterioration processes.

Also, some newer cars have alternators with computer-controlled clutches, which makes possible to disconnect it when there are no charging needs and improve fuel efficiency. However, this clutch can fail, leaving the alternator disconnected.

Any of these situations will cause a low charge scenario, where there will not be enough electrical power to run all the appliances and fill up the battery.

How to Check the Condition of Your Battery

When checking your battery, start by measuring the charge it holds. With the engine turned off, the charge level should be to the max. You can find detailed instructions for measuring voltage towards the end of this article. If you get reading below 11 volts, connect the battery charger overnight and then re-check the voltage it holds after a drive.

Next, see if there are any damages or cracks on the battery housing, as this would cause electrolyte leaks on the wet battery type. Also, check the electrolyte level and top it with distilled water if needed.

Last, make sure there are no traces of corrosion on the battery terminals, as this can decrease electrical conductivity. If you notice any corrosion or other deposits, use some baking soda with water or a wire brush to clean it off.

What Else Can Cause Charging Issues?

While a faulty alternator, just like a bad battery or corrosion buildup on terminal covers most of the usual causes of charging issues and flat batteries, there are several more things to look for.

First amongst them are fuses, as these will put the whole electrical circuit out of action. Check all fuses you can find under the hood or inside the cabin and replace bad ones, if there are any.

Other potential problem can be with loose connectors or half-broken wires, as these can cause sporadic charging and other electrical issues. To make sure you don’t have something like this, locate and check all connectors on battery, alternator and starter motor. Similar to connecting wires, they must be firm and with no visible damage. If you suspect that any of them is faulty, replace them as soon as possible.

How to Diagnose

If you have a newer cars, chances are it comes with a complex on-board systems that monitors various parameters while the engine is running, with charging level being one of them. If this is out of a predetermined range, not only will it trigger that red battery warning light on your dashboard, but it will also store a specific trouble code in the ECU memory.

Some cars will also have a specific message, such as ‘Alternator fault’ or ‘Charging issue’ showing up on trip-computer display. Combine this with trouble codes, which you can access using a scan tool, and you can get a good idea of what is causing the problem.

However, older cars don’t have this option, meaning you will have to use more basic diagnostic methods. This is where measuring the battery voltage can help pinpoint the problem. This simple test procedure will give a good insight into the condition of the battery and the electrical system. You should do this in two stages, using a multimeter.

  • While the engine is off, measure the voltage between the battery terminals. A good battery that holds the charge will give between 12 and 12.5 volts. On the other hand, readings below 11 volts show either a bad battery or an alternator that is not charging at a sufficient rate.
  • Repeat the measuring procedure with engine turned on and idling. Good alternator will produce between 13.5 and 14.5 volts. Anything below or above these values is a sign of a charging problem. This can be because of the failing alternator, bad wires or poor connection.


If you notice a red, battery shaped warning light that stays illuminated on your dashboard while you are driving, then your car is probably having a problem within the charging system. Some other symptoms that might point towards this issue are flat battery, slow cranking and dimmed headlights.

If you notice any of these telltale signs, check your alternator, battery, and other electrical components with no delay. Otherwise, you may end up stranded by the side of the road.




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