Knowledge Base

How Many Watts Does a Car Alternator Produce? (Power Output Test)

By:Michael Johns

alternator power output header

On this page, you will find out how many watts a car alternator produces

If you’re looking to access electricity when away from the utility grid, then a vehicle alternator is your best friend. With the engine running, your alternator can send a constant supply of electricity to your battery. You can then draw power from your battery via a power inverter to deliver AC electricity.

One thing you need to check it’s the power consumption of your inverter compared to your alternator. You must ensure you’re not overloading your alternator and ending up with a flat battery!

Below we will discuss and test car alternator wattage, explain how to work it out for yourself, and what you can run.

How Many Watts is a Car Alternator?

The average car alternator produces between 500 and 2000 watts.

The exact number depends on the size and model of your car alternator. For example, the alternator of a small older car puts out around 500W. While larger modern saloons and SUV alternators reach 2000W or more.

In the 21st century, the power output of a car’s alternator has grown rapidly. Even small hatchbacks like a Ford Focus or Volvo C30 output at least 1260W from their alternators.

In larger and luxury automobiles, the alternator size increases further to 2000W+. This is because it is required to run more electronics including AC, electric windows, stereos, electric seats, seat warmers, and parking sensors.

How to Find Out Your Car Alternator Wattage

There’s 2 ways you can work out the wattage of a car alternator.

  1. Wattage Formula or Calculator

If you know the amperage and voltage of your car alternator you can use this to find the maximum watt rating. The specification of an alternator should be marked with the amps and voltage.

A multimeter is another brilliant for getting a live wattage, voltage, and amperage reading. You can hook it up to your car alternator to get instant information. 

Simply use the formula Amps x Volts = Watts. Or you can head over to the ‘Watt Calculator’ to work this out.

  1. Check Car Specification

The quickest way is to look at the car alternator’s specification. The watts (W) is sometimes marked in the user manual or the manufacturer’s website for technical details.

Car Alternator Wattage Examples

Let’s take a look at specific examples of how many watts a car alternator draws. Below is a collection of modern car alternators with their listed power ratings.

Alternator ModelPower Rating (Watts)
LAUBER Alternator CQ1011426 (NISSAN: Pathfinder 3)1800
Denso Alternator 401651105 (Volvo V70)1260
RIDEX 4G0209 (Peugeot 107)980
Denso Alternator 401630020  (Jaguar XJ 8)1680
LUCAS Electrical LRA00471 (CITROËN C15)700
Bosch Alternator 401661130 (VW Transporter)1680
ALANKO 10441814 Alternator (Mercedes C Class)1080
DRI 2141881802 Alternator (Land Rover Defender)2520
DENSO DAN930 (FORD Focus C-Max)2100

As you can see, the power ratings vary between different car alternators. So you should take the time to check your own appliance.

Using a Car Alternator for Off-Grid Electricity

The cool thing about your automobile’s alternator is that you can use it to generate electricity! You can turn your car into a generator, anywhere, anytime.

Your car electronics work by drawing electricity from the starter battery. It’s the alternator’s job to convert energy supplied by the engine into electricity. This electricity from the alternator is then used to charge the car battery.

With a car power inverter, you can draw the DC electricity in the battery and convert it into AC electricity. By hooking up an inverter to your battery you can run appliances and tools like drills, air compressors, lighting, speakers, and much more.

Knowing the power of your alternator ensures you don’t overload your system when using the inverter. If you draw a higher wattage than your alternator provides will leave you with a flat battery. This is because you are drawing energy from your battery quicker than the alternator can recharge it. Plus you’ll likely burn out your alternator and battery. 

Is a Car Alternator AC or DC?

Your car alternator outputs direct current, also known as DC. This is because you can only store DC electricity in a battery. Due to this, all car electronics are designed to run on DC power. If you want to access AC electricity in your vehicle you need to use an inverter. 

Inverters can be connected to the 12V cigarette lighter port inside your car. This power allows you to draw upto 150 watts of power and convert it into AC via an inverter. If you want to pull more than 150 watts, then you need to connect the inverter directly to the battery. This will give you access to the full power provided by the alternator.

How Many Watts Does a Car Alternator Output Summary

I hope you now have a clear understanding of how many watts a car alternator produces.

As you can see, modern vehicle alternators deliver a decent amount of power. This is good news if you plan to run power tools or other significant electrical devices. The majority of modern cars can give you at least 1000W, plus larger SUVs and trucks now reach 2000W or more. Just remember to double-check what your vehicle can handle. Trying to pull too much power causes serious problems like flat batteries and burnt out alternators!