How Much Charge Does a Car Battery Need to Start?

Sometimes when starting a battery, the voltage may be too low. Therefore, there is a specified charge that the battery needs to start. 

For cars that are fitted with 12V engines, the average value that is needed before the battery can start is between 12.2V and 12.8V. This value should not exceed 14.8V after the car has started. On the other hand, when the voltage of starting power is below 11.8V, it will not be possible to start the engine. 

This article delves deeper into the topic, explaining the minimum and maximum charge that the battery needs to start

How Do You Know If Your Car Battery Is Low?

Your car’s battery powers the starter motor during ignition, and provides power for other electrical peripherals such as the headlights, sensors, dashboard, and stereo system.

When your car battery charge is low, it may crank slowly or be unable to crank totally, and the engine lights will be on indicating that the battery is running out.

You can use a digital voltmeter to measure your vehicle battery’s voltage by connecting its probes across the battery terminals. The voltage reading is indicative of the amount of charge that your battery contains.

A functional, fully charged car battery has a voltage reading of around 12.65 volts, while a dead or fully discharged car battery should give a typical voltage reading of 12 volts.

What Voltage Is Too Low for a Car Battery?

The general rule of thumb is, a voltage below 12.2 volts is considered too low for a car battery. and could indicate a fault such as a defective battery.

At this voltage, your car will not only be unable to crank up and start, but also your car battery undergoes sulfation; chemical changes that degrade the battery’s performance. Your car battery’s voltage should yield a value of 12.65 or higher if fully charged and healthy.

A car battery’s charge holding capacity reduces with time, and the typical battery life is between three and five years before replacement is necessary. 

Will Starting My Car Every 5 to 6 Days Recharge My Battery?

Simply starting your car every 5 to 6 days will not recharge your battery. On starting, the vehicle draws the maximum amount of power from the battery and coupled with the battery being idle for all that time, the battery’s charge holding capacity is severely degraded to a point that may necessitate its replacement.

Driving your vehicle for at least 30 minutes a week, at highway speeds will allow the alternator to charge and maintain the battery up to a point. You could disconnect the battery’s negative terminal to prevent the vehicle from drawing power from the battery when kept idle for long periods. 

The best solution, however, for long-term storage is to hook up your car battery to a smart charger, which will not only recharge your battery optimally but also provide a trickle charging current to maintain the battery at full charge and peak performance.

A smart charger offers the unique advantage of eliminating the need to start and run your vehicle every so often to keep the battery charged.

Also Read: How Much Does It Cost to Bulletproof a 6.0L Powerstroke?

Do Car Batteries Charge When the Engine Is Off?

It is impossible for car batteries to charge with the engine off. Running the car’s engine powers the alternator, a form of generator that outputs the voltage to charge the car’s batteries and power other auxiliary electrical facilities.

This is why you may find your car batteries flat and unable to start when you play music on the car’s stereo or run the AC for a prolonged time with the engine shut off.

Are 11 Volts Enough to Start a Car?

A battery voltage of 11 volts is insufficient to start a car. In fact, at 11 volts, your battery may be faulty, since a known good battery should typically have a low voltage of around 12 volts. You will have to jump-start your car with a well-charged battery

Are 12.4 Volts Ok to Start a Car?

12.4v battery is capable of starting a car. In fact, any voltage ranging between 12.2 volts and 12.6 volts can efficiently turn on your engine while a voltage reading less than 12.2 volts should be a cause for concern.

Also Read: How Do I Know if My Car Is 2WD or 4WD?


Usually, insufficient voltage to start a battery will be accompanied by some characteristics that are easily detectable. For instance, you may feel the starter is weaker when starting the vehicle, hence you have to ignite it several times. Another scenario is when the car has not been started for a long time, hence the lead-acid battery discharges causing low voltage. 

There are different options that you can apply here. The common one is calling an auto repair to check it out. Also, you can use a multimeter to check battery voltage and carry around a portable jump starter. 

The exact power required will tend to vary depending on the type of battery you have. However, the amps should be between 400 to 600 so your battery can start. For relatively small batteries, this value may be 150 amps and larger commercial vehicles may require 1500 to 2000 amps. 

Final Thoughts

Learning about your car may take a while, but it is important to do so in the long run. It will spare you a lot of frustration, time, and money. This involves understanding the intricacies of batteries and what is needed to start a dead battery.

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