How Many Watts Can You Run Off a Car Battery?

The answer to this question depends on the size of the battery. The battery is a rechargeable power source that helps power all the electrical components in the car. The battery capacity is measured in watts, which determines the amount of charge the battery can hold. So, how much watts can the car battery hold at a point in time? Read on to find out.

How to check your battery watts

Car batteries store energy which is referred to as power capacity. The unit for measuring this power capacity is watt-hour. Before we check the number of watts a battery has, we first have to understand some terms related to the energy produced by the battery.

  • Ampere: this is the electrical charge flowing at a point in one second. The unit for ampere is ampere-hour (Ah). It can be measured using an ampere measurement device.
  • Voltage: this is the quantity of energy that an electric circuit receives. The unit for voltage is voltage (V).

This will help us know how to check the watts in a battery. Watt is the result of the multiplication of voltage and ampere. The formula for calculating watts is:

Watt= Ampere X Voltage

The voltage and the ampere of the battery can be obtained using a device called a multimeter.

car multimeter

How many watts in a car battery?

The first step is to find the ampere the car can produce. This can be measured using a multimeter. As for the voltage, most batteries are made of cells that contain metal plates of lead and lead oxide each, producing 12V of energy. A typical car battery has an ampere of 60Ah and a voltage of 12V. Using the formula stated above, we can get the watts by multiplying the ampere and voltage. The watt of a typical battery is 720 watts-hour which can last up to 2hours on average depending on how the electrical component in the car is used.

How many watts does a car use?

This depends on the kind of battery and car you use. The more amps the battery draws out, the less power it has. Many batteries have a 10 hours or 20 hours power rating. A typical battery can hold 5amps for 10 hours. With an ampere of 50Ah and a voltage of 12V, the power the battery holds is about 600 watts-hour. Based on the 20 hours rating, the battery produces an ampere of 54Ah, which produces a power of 648 watts-hour. However, due to the difference in cars and the system they contain, measuring your car’s power usage is the best way to find out the watts your car uses.

How many watts to start a car?

The number of watts Depends on the year, make, and model of the car and how well the battery has been taken care of. However, a typical 12V battery will have about 60 watts-hours when starting the car.

Essential things to consider before choosing a car battery

There are some essential factors you should consider before buying a new battery. These factors include:

  • Battery brand: Be meticulous about the battery you want to buy, ensuring that the battery is from a well-known brand to ensure reliability and durability. Make sure whatever brand you choose has all the features you want in a battery. 
  • Power rating: it is best to know the battery’s power capacity to know how much load it can handle before being drained and the amps the battery offer for starting and keeping the car running.
  • The battery’s service life: Knowing the battery‘s shell life or service life can be the difference in how long your battery will last. Getting a battery with a longer service life will save you money by lasting for a couple of years.
  • The main battery feature: knowing the main features of the battery helps you determine what the battery offers and if it can satisfy your needs and the car’s needs.
  • Ability to start the engine at a cold temperature: it is essential to consider how the battery will function at a cold temperature. The cold temperature causes difficulties in the car starting as it may not have enough charge. Choosing the correct battery will ensure the car starts, but the battery keeps it running. 
  • Price: battery price depends on its size, service life, type, brand, and reserve capacity. Having the correct information will help you make an informed decision and fit within your budget range.
  • Battery size: because cars are different, they use different battery sizes. Consult the car manual to check the right size and dimension for your car if you want to buy a battery. Having the right size can save you stress in finding a good battery for your car.
  • Battery Warranty: Besides that, warranties protect you from defective products; it also saves help save money in the future. Ensure the battery you are buying is backed by good customer service and warranties, as this helps save cost whenever the battery breaks.
  • Battery reserved capacity: this is an essential factor to consider. The battery reserved capacity indicates how long a battery can last without recharging. Choosing a high-capacity battery will help the battery function well if there is a problem with recharging the battery.
automobile battery

How to prolong the lifespan of a car battery?

Maintaining the battery health can help keep up the power capacity(watts) of the battery and prolong the battery life. These are some ways to help maintain the battery:

  • Regular cleaning of the battery terminals and make sure they are tightly secured
  • Using insulation to protect battery content against temperature changes
  • Invest in a good battery that has a long service lifespan
  • Unplug the battery, especially when you are not using the car for an extended period.
  • Check the battery water regularly.


Knowing the number of watt-hours a battery has is essential. It helps you buy the correct battery for the car and not overstress the battery when using electrical components. Also, checking the battery capacity always helps you know if the battery is functioning well and working at full capacity and reduces the risk of malfunction if the battery is left unchecked.

Similar Posts