How many Amps & Watts does a Car Alternator put out?

Due to the replacement of the engine driver loads in the car with the electrically powered versions of the car are increasing. An alternator is a machine that is used all around us and it is impossible that an engine works without an alternator in a car, Trucks, buses, RVs, boats, etc. So this article will guide you about how many amps and Watts a car alternator puts out. 

How many amps a car alternator puts out? 

An amp basically represents a unit that explains the current flow in an electrical circuit.

  • On average the late model vehicles have an alternator rating range from 60 or 70 amps up to 150 amps or more . Because the older vehicles do have few accessories.
  • New model vehicles do have lots of Electronics and accessories so they need the alternator from 120 to 160 amps. The upgraded alternator is able to generate up to 200 amps.
  • The load of the am does depend upon funny factors which are explained next. 
Car Alternator
Car Alternator

Factors for amp load:

  • The first factor is the battery’s state of charge. 
  • The electrical devices which are used in the car will consume some power. 
  • The car in the cold morning is able to pull up to 200 amps or more to start from the battery.
  • The amp load by the ignition system is from 4 to 6 amps
  • The fuel pump and injectors as the amp load from 6 to 8 amps
  • The headlights of the car are able to consume up to 15 to 40 amps
  • The electrical defroster consumes up to 20 to 25 amps
  • The heated seeds consume up to 5 to 7 amps per seat. 
  • The wiper used in a car consumes up to 6 amps
  • If you use AC or a blower then the amp load on the battery is from 15 to 20 amps or more.
  • The sound system has an amp load of up to 10 to 40 amps.

What to do when the alternator or starter fails?

In case there is not a good balance between the amps that are put into the battery by the alternator and the amps pulled out by the battery then there are many problems that are being faced such as the battery does not remain charged, the vehicle will not get started easily, etc. Then you need to check the charging system and the starting system of the vehicle and check where the problem was before spending money unnecessarily to replace or buy a new system.

Car Alternator
Car Alternator

How many watts does a car alternator pull out? 

It is good to know how many watts does a car alternative puts out as in this way you can decide the size of the alternator you need to keep the battery charged while driving. As if the output of the alternator is higher the better will be the performance of the car.

  • The average voltage a car pulls out is about 1500 words. 

A person needs to have a correct alternator so that the car is able to run the important part of the car. The alternator usually converts the power generated from the internal combustion engine into electricity so that the battery of the car is able to use it.

The following table will explain the voltage of a car alternative pullout according to the alternator amps and voltage:

Alternator AmpsVoltageWattage

What is the car charging system? 

The charging system of the car should be in a way that it produces more voltage than the battery-rated voltage so that the batteries are able to overcome any internal resistance and the average voltage produced by a charging system is generally between 13.5 volts and 14.4 volts. The charging rate of the car will be faster if there is a great difference between the battery voltage and the alternator output voltage.

Car Alternator
Car Alternator

The different types of cars do have different speeds of alternators such as:

  • The ratio of the speed between the engine and the alternator is about 1:1 of a racing car. 
  • The ratio of the speed between the engine and the alternator is 1:2 of a drag Car. 
  • The ratio of speed between the engine and alternator is 1:3 of a car which is commonly used to run in the street. 

The unit of the power is what and the voltage causes current to flow and then the energy is converted into power. According to the formula:

Power = voltage × current

The below-given diagram explains the vehicle charging system it is represented as the alternator battery and the vehicle loads:

Car Alternator
Car Alternator


So if the alternative current is high at a low speed then the battery voltage will drop and the battery will need more time to be fully charged as it consumes more voltage. 


Can we turn an alternator into a generator? 

No, we cannot use an alternator instead of a generator because an alternator is used to convert mechanical energy into AC electrical energy and a generator is a device that converts mechanical energy into either AC or DC electrical energy.

Rick Costa

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