Typical Automotive Cooling Fan

Cooling Fan In-Rush Current

We get a lot of questions about cooling fans and whether or not you can drive them directly from a POWERCELL output without a relay.  In this post we’re going to talk about cooling fan in-rush current and show you what this looks like.

Any motor has an in-rush of current that flows through it upon start up.  To keep this simple, the windings of the motor look like a short circuit until they start to turn.  At start up, the current flow through the windings is high but settles down to a steady-state current level when the motor gets to its operating speed.  This peak in-rush current can be 4 to 8 times the steady-state current, depending on the motor.

When you buy a typical cooling fan, the manufacturer will tell you that you need a high-current relay to switch the fan on and off.  Typically these relays are 40 or 70-amps.  You need to use a relay with contacts that are sized to handle the in-rush current that flows to the motor.  With our Infinitybox system, we don’t use relays.  We use MOSFETs designed to control inductive loads like motors.  The point of this blog post is to show you what the in-rush looks like on a typical cooling fan.

We used the cooling fan in our 1979 Jeep CJ7 to get a real-life example of what this in-rush looks like.  The fan has a 16″ diameter and we powered it directly from the Jeep’s battery.

Here’s how we collected the data for this graph.  We used a precision current shunt in series between the battery and the cooling fan.  We used a Keysight DSOX1202G Digital Storage Oscilloscope to measure the voltage drop across the current shunt.  The shunt that we used was calibrated to 100 mV per 1 amp of current.  The battery was fully charged to 12.7 volts and the fan was mounted in the radiator shroud against the radiator.  We used a switch to trigger the fan and captured the waveforms.  This picture shows the current flowing to the cooling fan motor over time.

Cooling Fan In-Rush Current

Cooling Fan In-Rush Current

You can see that there is an in-rush of current flowing to the cooling fan motor when it starts.  This in-rush peaks at about 43 amps then settles down to a steady-state current flow of 12.3 amps.

Our POWERCELL outputs are designed to carry a steady-state current of 25-amps.  The MOSFETs that we use have surge current rating of over 100-amps and the terminals that we use have surge current ratings of 70-amps.  Running a cooling fan like the one in our Jeep is very easy for our POWERCELL to switch directly from an output without a relay.

Our Infinitybox system has an added feature that you can’t get from a relay.  Since we are using MOSFETs, we can do something called Pulse Width Modulation or PWM.  This lets us turn the POWERCELL outputs on and off thousands of times each second.  Using PWM lets us efficiently control the flow of current from a POWERCELL output.  For fans, we do something called soft-starting.  This lets us gradually ramp up the current to the fan to smooth out the in-rush current.  We’ve blogged about this before.  You can read it here.  

Stay tuned for a follow up post that will show the effect of PWM on the in-rush current flowing to our Jeep cooling fan.  Click here to contact our team if you have any questions about this post or anything else related to wiring with the Infinitybox system.


Picture of the IDIDIT id.TOUCH System

Wiring the IDIDIT idTOUCH

This blog post is going to show you how to wire the IDIDIT id.TOUCH PKE system to the Infinitybox 20-Circuit Kit.  The Infinitybox system is the electrical backbone for your restoration, resto-mod, street rod, kit car, or Pro-Touring build.  Our system is flexible enough to connect and power any external electrical accessory that you want to add.  In the case of wiring the IDIDIT id.TOUCH, your 20-Circuit Kit is already powering your ignition, starter solenoid and accessories.  You are going to use the id.TOUCH as the switches that connect to the MASTERCELL to control these functions.  Keep reading to learn more.

Before we go to far, please carefully read and understand all of the instructions that came with your IDIDIT id.TOUCH system.  You can access the manual from the IDIDIT website by clicking this link.  This blog post is only going to cover the wiring and connections related to the Infinitybox system.  Please follow their instructions for the complete wiring.

Wiring the IDIDIT id.TOUCH to the Infinitybox 20-Circuit Kit is pretty easy.  To the MASTERCELL, the id.TOUCH is just going to look like any ignition & starter switch.  This wiring diagram shows the details.

Wiring diagram showing how to connect the IDIDIT id.TOUCH PKE System to the Infinitybox System for Ignition and Starting Functions

Wiring diagram showing how to connect the IDIDIT id.TOUCH PKE System to the Infinitybox System for Ignition and Starting Functions

The connections that you are concerned about are the id.TOUCH outputs for the ignition, starter solenoid and the accessories.  You also need to wire the id.TOUCH input for the brake pedal signal.

For the id.TOUCH outputs for the ignition, starter solenoid and accessories, these are positive 12-volt signals.  Our MASTERCELL needs ground triggers.  Do not wire the outputs from the id.TOUCH directly to the MASTERCELL inputs.  This can potentially damage the MASTERCELL and will void your warranty.  You need to either use a small relay to invert these signals or use our inVERT  Minis.  The wiring diagram shows the correct wiring of the inVERT Mini.

Check the configuration sheet that came with your Infinitybox 20-Circuit for the correct wire colors for the inputs and outputs mentioned in this blog post.  You can learn more about the configuration sheet at this link.

The diagram from IDIDIT shows a neutral safety switch on the purple wire going to the starter solenoid.  You do not need to wire this with the Infinitybox system.  There is a separate neutral safety input that goes to the MASTERCELL.  See this link for more details.

The id.TOUCH has an accessory output wire on it.  That can be wired to the MASTERCELL to control any of the OPEN outputs on the system.  This can be used to control an output separate from the ignition to power your stereo or anything else that you want separate from the ignition.

You also need to connect the POWERCELL brake light output to the brake pedal input on the id.TOUCH.  The id.TOUCH needs a positive 12-volt signal to know that you foot is on the brake pedal.

Once you have the ignition, starter solenoid and accessories controlled by your IDIDIT id.TOUCH, you can add more optional features.  The id.TOUCH has a set of relays built in that can be used to control optional functions in the car.  For example, you could add a trunk popper.  Or you could control your door locks if you have our inMOTION cell as part of your Infinitybox system.  See the id.TOUCH manual for more details about setting this up.  This diagram shows how to wire the optional functions on the id.TOUCH to your MASTERCELL inputs.

Optional Wiring Harness Integration for IDIDIT id.TOUCH PKE System and the Infinitybox System

Optional Wiring Harness Integration for IDIDIT id.TOUCH PKE System and the Infinitybox System

The optional control relays on the id.TOUCH are not connected to power or ground, which makes wiring them very easy.  You simply need to ground the Green, Blue and Black/Wires in the optional harness.  The MASTERCELL inputs for lock and unlock on inMOTION would connect to the Green/Black and Blue/Black wires, respectively.  Any additional MASTERCELL inputs for accessories would connect to the Yellow and Orange wires.

The combination of the Infinitybox 20-Circuit Kit and the IDIDIT id.TOUCH gives you modern functionality in your restoration, restomod, street rod, kit car or Pro-Touring build.  You can download a PDF of these wiring diagrams by clicking this link.

Click on this link to contact our technical support team with any questions about these wiring diagrams.



1955 Cadillac DeVille- Great 8 Winner

Congratulations to Frank Hinmon for being a Great 8 Winner at the 2020 Detroit Autorama.  Frank and his team have put a ton of effort into this car to make it the best and it shows.  In addition to making it to the Great 8 at the Detroit Autorama, his car was one of the Select Six at the Chicago World of Wheels.

The car is an engineering masterpiece.  It is full of detail.  They started with a 2-door and re-engineered it to make it a 4-door.  From there, the paint, the interior, the engine, the chassis are all integrated seamlessly to create this Great 8 Winner.  Check out this video to see the full details.

1955 Cadillac Deville: Great 8 Winner at Detroit Autorama from eclassicautos on Vimeo.

Thanks to EClassic Autos for the great video coverage at the show.

Frank wired the car with a complete Infinitybox system including our 20-Circuit Kit, 2 inMOTION cells, inTOUCH NET, inRESERVE and inVIRONMENT.

Beyond all of the body modifications and mechanical details in the car, this is a complicated car, electrically.  Using the Infinitybox system made creating a complicated wiring system very easy.  The car was wired with off-the shelf components from Infinitybox and configured through software to do what Frank wanted it to do.  The distributed architecture of the Infinitybox system made the runs of wire short and kept the bulk of the harness to a minimum.

Frank has inTOUCH NET as part of this system so he can control the entire car from his iPad tablet or a touch screen head unit mounted in the dash.  His windows can be controlled from the iPad so can the door poppers.  This also includes using our inMOTION motor controller cell to raise the hood and the trunk by pushing a button on his tablet.

We also customized the system to manage his fuel tank controller.  Frank has two different fuel tanks: one for pump gas and one for racing gas.  He has a special valve that flips between these two different tanks and their fuel pumps.  By using outputs from one of his inMOTION cells, we control the actuator that flips the valves between these two tanks.

The power, flexibility and versatility of the Infinitybox system gave Frank the control he needed to wire this winning car.  The entire Infinitybox team is proud to be a part of this project.  Congratulations again to Frank for an award well deserved.

Jay Harris and Frank Hinmon at the 2020 Detroit Autorama.

Jay Harris and Frank Hinmon at the 2020 Detroit Autorama. Frank’s Cadillac was awarded as one of the Great 8 winners for the 2020 Ridler Award.

Click on this link to contact the Infinitybox team to learn more about our full range of wiring and electrical products.

Illegal Garage’s Alumacobra Switch Install

We just received a great video from a local customer building a Factory Five Roadster.  Jose G. has been building this car for a few years and he’s wiring it with our Infinitybox system.  He is installing our 20-Circuit Kit with inLINKThis link will take you to an earlier blog post covering his progress.

He has a very slick and elegant aluminum dash that has modular panels.  He can easily remove and install panels for his switches and gauges.  It would certainly make working on the dash very easy.  Jose was recently at the London Cobra show in Ohio and saw a new set of switches he wanted to integrate into his dash.  These are nice looking billet buttons and he wants to use them for his lights, fans, wipers, fuel pump and one-button start.  These buttons are from Billet Automotive Buttons in Australia.  Installing these buttons shows the simplicity and the ease of wiring your car with our Infinitybox system.

First, our MASTERCELL inputs are ground triggered.  This gives you a lot of flexibility of how you can wire your switches.  This simple diagram shows how you wire a MASTERCELL input to your switch.


Simple Switch Diagram

You can click on this link to get a more detailed blog post talking about wiring switches.

Another significant advantage of wiring your switches with our Infinitybox system is the fact that it takes very little current to turn on an input.  It takes less than 1 milliamp (1/1000 of an amp) to trigger an input.  That gives you the flexibility of using any switch to control the functions in your car.  With a lot of billet buttons, you have to use them to trigger a relay because they cannot handle the full load current of things like lights, starter solenoids and fans.  This is very easy with our Infinitybox system.

Since it takes so little current to turn on a MASTERCELL input, you can use very light-gauge wires between your switches and the MASTERCELL.  Our standard harnesses use 22-AWG wire.  This helps keep behind your dash clean and easy to service.

Lastly, we give you the power of advanced electrical control functions.  In the case of Jose’s car, he’s using our One-Button Start feature.  A single MASTERCELL input connected to a momentary button lets him start his car with ease.  Check out this blog post for more details on our One-Button-Start feature.

Jose just posted a great video to his YouTube channel, The Illegal Garage, showing off how he installed these billed buttons into his Cobra.  You can check it out below.

You can check out additional videos of his Factory Five Cobra build at his YouTube channel by clicking this link.

Click this link to get in touch with our team to learn more about how you can wire your car or truck with our Infinitybox system.

Supercar Blondie Test Drives Tachyon Speed

Eric Rice and his team at RASER have been getting some great press coverage for their Tachyon Speed.  This is a one-of-a-kind super car.  It’s all electric, it’s styled like a fighter jet and it can put out enough peak power to meet the needs of a small city.  Just like any other car, it needs an electrical wiring system to manage all of the functions in the car.  The RAESR team turned to Infinitybox to get the most advanced electrical system on the market to meet their customers’ needs.

The Tachyon Speed caught the eye of Alex Hirschi, aka Supercar Blondie.  Australian-born Alex is a world renown celebrity in the super car space.  She now calls Dubai her home and was recently listed as one of the top 30 most influential women in the Arab World.  Her blogs, videos and TV appearances have been viewed billions of times by aficionados of exotic and super cars.  She is an expert on all automotive thoroughbreds.  Alex made the trip out to LA to meet with the RASER team and test drive the Tachyon Speed.  She ran the car through its paces on the road.  She also had a chance to play with the touch screens and switch interfaces that are controlled by the Infinitybox system in the car.

The Supercar Blondie team posted a video showing Alex meeting with the RAESR team, touring the car and taking it on the road.  Check out the video below.

We congratulate Eric and his team for what they’ve accomplished with the Tachyon Speed.  We are proud to be a part of this car.

Our Infinitybox system was designed for any type of car, truck or race car.  You may not be building a super car but you can get the same functionality and features in your restoration, street-rod, kit car or Pro-Touring build.  Click this link to contact our team to learn more.

You can learn more about RAESR and the Tachyon Speed by clicking this link.