What Does Car Low Battery Mean?

What Does Car Low Battery Mean? A car battery is an essential component of your car. Many accessories and components of your car will fail to work if the battery has a low voltage or is not functioning at all. 

A car battery can last for as long as five years if proper maintenance tips are followed. A fully charged and healthy battery should read between 13.4V and 14.7V when the engine is operating and 12.6V when the engine is not in use.

A car’s low voltage battery means that your battery voltage is too low such that it cannot power several components of the car. It might only be able to power the engine which will eventually fail in a short time. 

When a car battery reads below 12.2V, it means the voltage is low and you should consider recharging it or replacing it because sometimes it might be the case of a damaged battery.

Also, a low voltage battery might imply that the alternator is not providing enough current to charge the battery. The alternator in a car converts mechanical energy to electrical energy to help power the car battery and other electrical components. So, if the alternator is not functioning well, it will cause a low battery voltage.

What Does Car Low Battery Mean

Causes of Car Low Battery

Several factors will cause your battery’s voltage to be low and incapable of providing enough power to other components of your car. 

Some of the causes include:

Loose connections

If the electrical connections that link the battery to the electrical components of the car like the starter, fuse box, ignition coil, and dashboard electrical components are loose or corroded, it will appear like there is a low voltage battery because these components will not function the way they should due to a diminished power supply.

So, you’d have to make sure there are no loose connections before you can blame the battery for supplying low voltage.

Faulty alternator

A bad alternator is one of the major causes of a low voltage battery. 

The alternator charges the battery while the car is in use to maintain the battery’s voltage. The unit produces an alternating current to the car battery for charging. 

A strong and fully charged car battery can last for up to two hours or more while in use and the alternator ensures the battery is kept charged to prevent the engine from stalling while you are using your vehicle or the voltage from getting low which will, in turn, affect other electrical components of the car.

Faulty battery/battery terminals

Sometimes, your battery can die off completely or produce very low voltage, this might not be because of not fully charging but due to an issue with the battery. It can be from using a depleted battery, having corroded battery terminals, or a leaky battery. 

It is important to always have a battery replacement with you in the car in case your battery fails at any point.

Faulty voltage regulator

A car’s voltage regulator when working optimally ensures the right amount of electrical power is flowing to different components of the car. 

A bad voltage regulator can be caused by an electrical short circuit or faulty alternator connection. If the voltage regulator is bad, it causes an uncontrolled charging sequence which can damage your car battery or cause it to display a low voltage which can still damage the battery in the long run.

Excessive electrical load

If the electrical load of your car is not compatible with the battery’s capacity, there will be a drop in the charging voltage which will lead to having a low battery voltage. 

A faulty cooling system for instance might cause this low voltage because the cooling system alone might begin to draw a large amount of current to itself, which makes it difficult for the battery to charge properly, especially when you have a massive cooling system that is not compatible with the battery capacity.

Malfunctioning ECU

The Electronic Control Unit (ECU) as the name implies is a car component or device that controls all electronic features of a car. 

The ECU controls fuel injection, braking and suspension, cabin temperature, and the ignition system. 

Sometimes we might mistake an ECU failure for a battery or alternator problem. This is because the ECU controls the charging system of some modern vehicles and any hardware or software issue with the ECU will cause a charging problem which will lead to a low voltage output from the battery.

Incompatible alternator and serpentine belt

A low-capacity alternator will not provide sufficient charging and voltage to the battery which will cause a low battery voltage output. It is important to use an alternator with a capacity that is sufficient for your car battery and electrical loads. 

The serpentine belt on the other hand can latch on to the alternator’s pulley and prevent it from turning at low revolutions per minute. This will result in a low charging output and will lead to having a low voltage battery.

What Voltage is too low for a car battery?

If your battery is below 12.4v, it indicates that the voltage is low. 

A healthy and fully charged 12-volt battery should be reading 12.6v and above. When your battery reads below 12.4v, it is between 40%-70% charged which indicates that it is getting low. 

At this point, your car lights begin to dim, some electrical components will not respond, and your engine might become difficult to crank. You can determine if your battery is too low by testing with a Voltmeter, and when your battery reads anything below 12.4v, it means the battery is undercharged or probably damaged and will need a recharge or replacement.

Any reading between 11.75v and 11.89v indicates that the battery is completely dead and needs a replacement as soon as possible to ensure the proper functioning of other car components. At this stage, the battery is no longer functional and no matter how much you charge it, it will not increase to the adequate voltage.

How Do You Know When Your Car Battery Is Low?

When your battery is low, your car will begin to show some signs. One of such is the engine starting very slowly. The battery gives the engine that power to crank and if it is low, you can notice it from the way the engine starts. 

The car battery gives power to all accessories and electrical components of the car. If the car lights get dim, it is an indication that the battery has a low voltage. Components such as headlights, dashboards, and radio will not function effectively if your battery is low. 

You can also determine the voltage of your battery by testing it with a voltmeter. Take note that faults from other car components can display similar symptoms. Hence, to be sure it is a low car battery or a faulty battery, you should simply test the battery directly.

What Does Car Low Battery Mean

Basics of Voltage Reading

Testing your battery voltage is important because this will help you to know if your battery is having a low voltage or if it’s completely dead and from there you know subsequent action to take. 

A good battery might show some symptoms of a dying battery when it is just a low voltage problem, testing this with a voltmeter/multimeter will enable you to decipher where the problem is coming from without wasting so much time.

A voltmeter is a device used for measuring voltage. It can be used to measure a voltage drop in a battery or across two components. 

A voltmeter is quite easy to use for voltage reading. 

All you need to do is to connect the positive cable of the voltmeter to the positive terminal of your battery and the negative cable to the negative battery terminal. If the voltage reading is not accurate, it means you have swapped the cables.

It is good to perform this test after about 12 hours of turning off your vehicle to give any surface charge the space to be dispelled. This will ensure you get a proper reading.

Take your reading carefully. A reading of about 12.6v to 12.8v indicates a fully charged and healthy battery. If the voltage reads above 12.8v, it means that your battery has excessive voltage, which means that it is overcharged, and you should try to drain the excess voltage by turning on some components in the car. In any case, a voltage reading of 12.8v and above is rare for a healthy battery.

If your battery voltage reads below 12.4v, it means that the voltage is low and needs charging. Any reading below 11.90v indicates that your battery is dead and needs a replacement.

How to Fix Low Voltage Car Battery

A low voltage car battery can be remedied by charging the battery. 

Starting your car uses up a lot of energy from the battery and the alternator refills this lost energy while the engine is on. To keep your battery voltage in check, ensure that your alternator is in good shape. 

The alternator serves as a source of power that recharges your battery while the engine is on. It might take about 30 minutes or more to charge completely.

A dead battery that usually reads below 12v can also cause a low voltage. 

If after conducting a load test on the battery or jump-starting your vehicle and the voltage range does not improve, the only available option is to get a new battery replacement.

Signs of a Dying Battery

A dying battery can fail and get you stranded when you least expected it. 

Howbeit, before this happens, it will show some symptoms such as:

Slow crank

A dying battery will cause your engine to crank sluggishly. When you turn the key in the ignition and your engine cranks slowly, this is a sign of a dying battery.

Dimmed headlights 

A dying car battery can’t properly power the car’s electrical components. The headlight for instance will become weaker and dim.


A dying car battery might cause your engine to backfire. 

Backfires occur because the battery causes sparks which leads to fuel accumulation in the cylinder. The fuel accumulation subsequently ignites and causes your car to backfire.

Clicking sound from the starter

Usually, the car battery sends a signal to the starter solenoid when the key is turned in the ignition to start the car. 

A failing battery will only send weak currents to the starter which makes it return a clicking sound.

The car starts and dies off immediately

A dying battery can cause your engine to come on and then go off immediately. This is because a failing battery causes interruptions to the signals it sends to the engine control unit.

Check engine light illuminates

The check engine light illumination might be a good indicator that your car battery is dying. The check engine light beaming might also indicate other problems with the engine.

Swollen battery case

A chemical reaction in the battery can make the battery case swell up. Also, extreme cold or hot weather can damage the battery and makes the battery case swell as a result.

Frequently Asked Questions

What happens when my battery gets too low?

It is important to always keep your battery charged. If it gets too low, it will affect several components of the car such as the engine, starter solenoid, accessories, and other electronic components. If your battery gets too low, like below 11.89 volts, it will become severely damaged due to excessive sulfation. 

How do I keep my car battery charged?

There are two major ways to keep your battery charged, one is through the alternator and the other is by using an external charger. However, the alternator charges the battery only when the engine is working. If the battery gets low while your engine is off, you will need an external charger to power your engine. If you don’t intend to use your car much frequently, you can keep your battery charged by driving or idling your car for at least 30 minutes a week.

What additional thing can drain my car battery?

To avoid having a drained battery, it is important to understand the things that can cause a battery problem. Knowing these things will help you avoid them, some of which include failure of the alternator to charge the battery while the engine is working, loosening or corroded battery connections, leaving your headlights or internal lights on and not properly closing your trunk, frequently going on short trips can drain your battery and reduce its lifespan because short trips don’t give the alternator enough time to charge your battery. Also, if your car temperature is extremely hot or extremely cold, it can drain your battery.

Why do I need a car battery charger?

Battery chargers are helpful for batteries that are not used frequently. However, your battery can fail when you least expected it and the alternator can only charge it when the engine is running. You might get into a situation where you’ve left your car idle for a little longer, sometimes, even overnight and you try to start it in the morning and it’s not coming on. At this point, you will need an external charger. Having a battery charger in your toolkit at this point makes all the difference.

How do I know when a car battery needs replacing?

Your car battery needs a replacement when it begins to exhibit the symptoms of a dying battery as discussed earlier. Some of those symptoms include dimming lights, malfunctioning electrical components, dashboard light illuminates, engine cranking slowly, etc. Most importantly, a voltmeter can help you know when to replace your car battery even before it fails. If your battery reads below 12v on your voltmeter, it is a sign that it might be dead and needs a replacement.

Can I drive with a low battery voltage?

Yes! If your battery is not completely dead, you can drive with a low battery voltage although your car might stall along the line. It will also be quite difficult to get the car started if your battery is low. One important tip is to turn off all electrical components where possible as this will reduce the power they are consuming and will preserve your battery a bit. Driving with a low battery voltage is not a good idea by the way, as uncertainties might occur and leave you stranded.