This is based on the draw from the fans if the fans are larger and draw more than 15 amps each it s recommended to install a second relay kit as shown below.
Radiator cooling fan amp draw.
The initial start up of the fan will have an amperage spike.
The relay fan control should be mounted on a clean surface with heatsink grease to allow the heat to dissapate into the frame.
Amperage used to measure how much load an electrical device draws when in operation.
Twelve to 16 inch fans can draw from 15 to 28 amps while some dual fan applications can draw up to 35 amps.
Puller style fans are recommended for applications in which the electric fan is the primary cooling source.
Pusher style fans mount on the front of the radiator and blow air through the radiator core.
I went and purchased a multimeter with a clamp on ammeter up to 40amps.
Wiring dual cooling fans with dual cooling fans there are two methods for wiring up the relay kit.
Typically the higher the airflow the higher the current draw will be.
The higher output fans that draw 25 amps and up may need a higher output alternator to keep the battery from going dead.
Puller style fans mount behind the radiator and draw air through the core.
Most of the spal fans can run off of the existing vehicle electrical system without any problems.
The fans should draw less than 40 amps so you will not be able to do this with a meter you install inline as they only do 10 amps typically.
The more powerful a fan is the more current it will draw from your vehicle s electrical system.
Look at the spec sheets.
Automotive fans are rated at 13 5 volts and the rating is after the motor is at operating rpm.