How Many Volts Does It Take to Start a Car?

What is Voltage?

Voltage is the amount of electrical potential a battery holds. Voltage is crucial to a vehicle’s performance because even a slight drop makes a big difference. It is the electromotive force or potential difference measures in Volts (V). In more descriptive terms, voltage is also defined as the pressure from a circuit’s power source that pushes charge through a conductor, enabling them to do work such as powering a light bulb.

car starter

How is Voltage Measured?

There are several ways to check a battery’s voltage. The standard method is by using a Voltmeter. A voltmeter is an instrument used to read the potential difference of a battery. It is attached to the connector ports of the car battery to give this reading.  

How To Use a Voltmeter

Before attaching the voltmeter, make sure the engine is turned off, and the alternator is not in an elevated or rising state. 

Here are the steps to take in using a voltmeter to measure voltage: 

  • Connect the voltmeter to the battery terminals.
  • Crank the engine up.
  • Check the voltmeter for the reading.
  • Continue cranking for about fifteen seconds more

The relatively good voltage rating required to start a car is about 9.6 volts. 

The voltmeter should read this rating during this period.

What If the Voltage Reading is Low? 

The recommended voltage rating for a car battery on starting is between 13.7 to 14.7 volts. This reading is an indication that your car is in good condition. However, if the voltage rating reads below the acceptable rating, it could be because of these reasons:

  • Cold temperature: Very low temperatures make the battery slower during ignition. The standard temperature for a battery to function is 70 degrees and above. Batteries give lower voltage during cold weather due to internal buildup. 
  • Damaged battery: Lower voltage reading is a sign that your car battery is probably damaged. A low voltage reading may mean that it is time to replace your car battery. 
  • Corroded or loose connections: corroding battery components can cause intermittent electrical problems, causing power to flow only at intervals. 
  • Faulty alternator: an alternator consists of a rotor, a stator, a regulator, and an internal rectifier. The alternator produces voltage and amperage to the battery during charging. 

How to Identify a Damaged Battery

  • Warning lights: Vehicles these days come with warning lights on the dashboard to warn the driver of any damage or problems with the car. 
  • Dimming of headlights: When the car headlights begin to fail, this is an indicator of a faulty battery because the car battery powers the headlights and other accessories. 
  • Slow engine cranking: when the engine would not start immediately or requires a pump on the gas and more time to start, this can indicate a damaged battery. 
  • Swollen or cracked battery case: most battery cases are made of plastic. A swollen case can be a sign of a faulty or worn-out battery. 
  • Excessive leakage: this is very common with standard wet cell batteries. Excessive acid leaks should be looked into urgently. 

How to Fix a Low Voltage Battery

Using a car battery charger in automatic float mode to maintain the charge after a full charge is a good way to up the voltage. An automatic float charger is designed with a floating circuit to prevent overcharging. 

Another method is the jump-start method. This involves connecting your car battery to another charged car battery. Let the battery stay in starting mode for about ninety seconds when using this method. 

It is important to use chargers that are compatible with your vehicle. 

Low Voltage vs. High Voltage 

Low voltage is safer, easier to handle unsupervised, and requires less energy. Any voltage below 50V is marked as low voltage. Low voltage wiring is used in thermostats, automatic garage door openers, alarm system sensors, audio-visual systems, RV LED lighting and other systems with low voltage needs. A disadvantage of low voltage wiring, however, is the loss of potential for energy across the wires.

High voltage transmits large amounts of power over long distances, such as electricity supply, to homes through high voltage power lines. High voltage should only be handled by experts because there is a high risk of hazard due to the large current flowing through the wires. Unlike low voltage wiring, an advantage of high voltage wiring is that it is more efficient, and energy loss is minimized as electricity travels from one location to the next. 


Can voltage be too high?

Yes. For a car with a 12V engine, voltage above 14.8V may be considered too high and could damage the battery. Make sure to check the engine stabilizer and regulate the battery voltage. 

Are a multimeter and voltmeter the same?

A voltmeter is only used to measure the potential difference between two points in a circuit. A multimeter, on the other hand, can be used for different functions. It is a multi-purpose instrument used for reading parameters such as capacitance, potential difference, resistance, frequency, current, etc. 

Can a multimeter measure voltage?

A multimeter can be used to measure voltage, but it is not limited to only that. It measures other parameters also. You can use a multimeter as a voltmeter by following these steps:

  • Turn the selector knob to either AC or DC.
  • Turn the meter selector dial off and connect the device across the two terminals of the element to be measured.
  • Take note of the reading displayed on the multimeter screen. 

Is voltage dangerous?

Voltage can be likened to the pressure that drives current, while current is the actual dangerous element. Any voltage above 30 volts is considered dangerous and could cause an accident. 

What happens when a system is connected to the wrong voltage?

If the voltage is less than the demand of the system or appliance, it will not function properly or even work at all. For example, if a heating system of 200V is connected to a 110V power source, it will most likely heat up very slowly or just barely heat up at all. 

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