What Does a Car’s Low Voltage Battery Mean? Top 4 Causes

Battery is one of the most important parts of the car that everyone should know about. Several accessories and the lights in the car are powered by this battery.

A battery can last up to five years, but you need to take good care of it in order to keep it functioning.


What does a car’s low voltage battery mean?

When you have a low voltage battery, it means that it needs to be charged or replaced.

An easy way to determine if a battery needs recharging is to check its voltage with a multimeter. A battery replacement may be necessary if the charge is continuously low.

According to AutoBatteries.com, a fully charged battery should measure over 12.6 volts. When the engine is running, this reading should be between 13.7 and 14.7 volts.

If the battery voltage is less than 12.45 volts, it is low (less than 75 percent charged) and needs to be recharged.


What causes a battery to have low voltage?

A low or weak battery in your car can be caused by a variety of factors. Sometimes weak batteries are caused by faulty alternators or parasitic drains.

Low battery voltage can also be caused by faulty battery connections. It is possible for loose or corroded connections to cause intermittent electrical problems.


1. Faulty Alternator

To make your car last longer, you need to charge the battery. The alternator of your car must be working properly and producing enough voltage and current to charge the battery.

The alternator converts mechanical energy into electrical energy. The motor consists of a rotor, stator, regulator (or voltage regulator), and an internal rectifier.

Your car’s battery is charged by an alternating current produced by the alternator.

Drive belts are rubber or fabric belts used to drive crankshafts and drive accessories. Alternator belts, fan belts, or accessory drive belts are examples of drive belts. 

In the event of a broken, frayed or clogged serpentine belt, the electrical components won’t be able to spin at their maximum speed, leading to a loss of power to the system.


2. Corroded or Loose Connections

Power is supplied from the battery to the vehicle’s electrical system, including the starter, ignition coil(s), fuse box(es), and dashboard components. Low voltage may result from this problem.

In the event of corroded or loose connections, intermittent electrical issues may occur.


3. Faulty Voltage Regulator

Volatile voltage regulators can result from faulty alternator connections or shorted electric circuits within the regulator, causing an uncontrolled charging sequence that destroys batteries.

You may also encounter voltage regulator issues if your battery is weak or bad.


4. Faulty Battery

If you want to use the low voltage battery again, you will need to recharge it, or you will need to replace it entirely if the other reasons no longer apply in this case. 

The first sign of a dead battery is when there is nothing left in your lights, and they dim when you turn on your car.

It is advisable to always have replacement batteries ready in case the battery of your vehicle dies completely. You can purchase a new battery at your local auto parts store.


At what voltage is a 12-volt battery considered dead?

An open-cell or resting battery voltage is what we refer to as “open-cell voltage”. A fully charged 12-volt battery rests at 12.8-12.9 volts, and a flat dead battery sits at 12.0 volts, so 12.4 volts represents about 50% charge on a resting battery.

According to BatteryStuff.com, a healthy 12-volt motorcycle battery should maintain 9.5 – 10.5 volts under load for at least 30 seconds.


How to measure a 12-volt battery?

There are several ways to check for a low voltage battery. You can use a multimeter with the testing probes attached to your ground and positive posts, respectively.

Voltmeters are the most reliable tool for checking whether a battery is still charged. Your battery is considered low if your voltmeter shows no reading or a reading of less than 12.4 volts. 

If the voltmeter shows 12.4 volts or more, the battery is working properly and the problem lies elsewhere.


Low voltage on car battery?

Low voltage batteries range from 11.8 to 12 volts. If you need to drive for a long time, prepare for a battery replacement due to the low voltage. 

In addition, a low voltage needs to be recharged before it can be used. However, it will have issues starting a car (headlights, horn, fuel gauge) and eventually won’t be able to start the vehicle.


Discharge battery

Battery voltage is less than 11.8 volts when discharged. When the battery is fully discharged, the car cannot start. It can be recharged, but it must be replaced soon. 

Fully discharged batteries take a short time to recharge, so you should use the car as soon as possible for safety reasons

In a discharged state, batteries should not be left for long periods of time. Don’t store your battery or make any changes to its voltage settings as this may cause irreversible damage to your car’s electrical components and permanently damage its battery.


How to fix low voltage car battery

Charge a car battery with a low voltage in several ways. When a battery is already fully charged, it’s a good idea to use a battery charger with a float mode.

You can jump start a car with low voltage by starting it from another vehicle and letting it run for at least half a minute while in the starting mode. You can then drive the car to a nearby shop for a replacement battery once the voltage has firmed up enough.

Despite the wide variety of battery chargers available, it is important to choose one that is suited to the needs of your 12-volt system as well as your vehicle.

From motorcycles to personal watercraft, universal types will work. 

In addition, there are dual-purpose chargers that perform both functions, but these are only compatible with certain battery types and sizes.

You will need to bring the battery outside and connect the charger if the battery is in a car located indoors.

You might need one of the smaller portable chargers if you do not have room to work on your vehicle.

In order to fix low voltage car batteries, you need to learn how to use portable chargers.



Therefore, the best way to detect low voltage on a car battery is to use a voltmeter. If the voltage is over 12,4 volts, then you can continue driving without needing a tow truck. 

If the voltmeter reading is below 12.4 volts, the battery is low and should be changed or replaced as soon as possible because a low voltage battery cannot provide enough power to run the car properly.

How helpful was this article to you? If you have any questions, please let me know. Leave a comment below!


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