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4×4 enthusiast of the month – Local man programs bluetooth tyre inflator/defaltor


As a serious 4×4 adventurer, you should know that crossing soft sand, muddy parts or any other terrain for that matter means that your tyres need to be inflated or deflated to suit various off-road challenges thrown its way.

Fyko is a local 4×4 enthusiast who has taken the time to code a very intelligent device called the ‘PneuMatic Pressure Control System’ which can benefit overlanders, and caravaners too, but before we get to that, here’s a little background on Fyko.

Fyko was born in Cape Town in November 1949 and lived in Plumstead. His family then moved after his father was transferred to Pretoria and then Johannesburg. After high school, Fyko did a Spca Comm diploma course and worked for the Hartebeeshoek Tracking Station during the time that “Neil Armstrong set foot on the moon”, says Fyko.

In the late 1970s, Fyko started an enterprise with a colleague to design and produce systems for what the industry of the day demanded. (Exact specifics not mentioned here.) The systems were successful because they worked. After the change in government, Fyko went on holiday and remained so 25 years later.

In between, he bought and sold a Waterberg game farm and sailed the oceans in his yacht. Fyko found himself in Mozambique where he started a tourist lodge in a coconut plantation on the shore of a tropical lagoon (Villa ‘d Cocos). While there, he corresponded occasionally with Godfrey Castle about technical questions arising from his magazine subscribers.

From 2012, Fyko’s visits to South Africa became longer and longer until he settled full-time in Fish Hoek, happily married.

“At some point, I bought a Jurgens Classique that had ewiks movers fitted, but the stand I had at Imhoff was a little tight and needed more mobility than the handheld ewiks control was able to provide. Hence I designed a remote contol using my mobile phone and Bluetooth to give me the extra mobility”, Fyko added.

Being also a website creator, Fyko built a website to describe the device to others who might have a similar need. He also submitted it to Erik Warburg at ewiks for evaluation. Subsequently, Fyko received requests for extensions and enhancements to the caravan remote control and expanded it to what it is today.

In between, Fyko still returned to Mozambique regularly, which meant deflating six wheels to get to his place. The last few kilometers were really soft sand and quite a challenge sometimes to get both bakkie and trailer across (initially an Xplorer, later a Conqueror Companion).

“I had a pretty good compressor (Chinese-built ARB), but the squatting beside each wheel for all those minutes (x 6) was a pain, so I created the remote control device to inflate and deflate from inside the car with a cold beer in hand. This requires a dedicated mobile phone app but actually uses the same control device as the caravan controller.”

“It’s not enough just to have a good compressor of you regularly inflate/deflate. You need all your kit in a convenient box, with a good hose and reliable and efficient electrical connections. Also if you deflate often you’re sooner or later going to damage a side wall, so you need repair kits, inner tubes, and tyre levers to hand. Preferably in the same box. The costs of all this stuff are a lot higher than the caravan controller so it appeals to a smaller section of people, some of whom can assemble the whole kit, others cannot. I build up boxes for those that cannot, and sell just the control unit to those that can”, concludes Fyko.

Back to the device!

This new and improved device offers a hassle-free, off-road experience and although someone will need to move the hose from wheel to wheel, everything is either automated or done while seated within the vehicle. The device can also switch a compressor on and off, electronically open and close a deflator valve, and measure hose pressure in an air hose connected to a pneumatic tyre.

Its contained in a plastic housing that has been specially designed to be mounted in the corner of a larger container that also houses a 12V compressor, an air hose, and other tyre maintenance accessories. The unit takes instruction from and reports to a mobile phone app via the Bluetooth communications medium.

The control unit has connections for:

  • An air hose that also connects to the compressor and tyre valve
  • A pair of 50A Anderson connectors that serve as power input and output These connectors are wired to power relays with 60A switching capacity. Either connector can act as input or output. Controller power is drawn from whichever is hot
  • There is an exhaust port to vent air from the deflation operation

The mobile phone app has the facilities to:

  • Display hose pressure (equal to tyre pressure when at rest)
  • Display battery voltage
  • Display the compressor On or Off
  • Display the deflator Open or Closed
  • Set Target Pressure
  • Display time to end of inflation/deflation phase
  • Specify 5 tyre size groups: V-Small, Small, Medium, Large, X-Large
  • Display Bluetooth connectedness
  • Switch the phone’s flashlight

It has buttons to:

  • Start and stop the compressor
  • Open and close the deflator valve
  • Initiate and end an automatic inflation/deflation operation
  • Adjust Target Pressure between 100kPa and 350kPa

How does the app work?

In Manual Mode there are no pressure or time limits. The compressor and deflator both stay active as long as commanded. You can start the compressor by tapping the left-hand green button. The button turns red and you stop the compressor by tapping it.

You can open the deflator valve by tapping the right-hand green button. The button turns red and you can close the deflator by tapping it. The deflator icon will show a red border whenever to hose pressure falls below 100kPa to warn of unstably low tyre pressure.

Tyre Pressure Indicator

The controller measures the hose pressure accurately, but hose pressure will not be the same as tyre pressure during either inflation or deflation. To measure tyre pressure accurately the both the compressor and deflator must be off for at least five seconds to allow the pressure in the tyre to equalise with the hose pressure.

Compressor Power Switch

The controller switches 12V current to the compressor through power relays with a 60A capacity. The compressor has its own power switch which is effectively wired in series with the controller relay contacts, which is why the compressor’s power switch must always be left in the ON position when the compressor is under remote control. If it is left off, the controller will not be able to run the compressor.

The controller has two 50A Anderson plugs through which 12V power is carried to and from the controller. Either plug can be an input and either plug can be an output. The controller taps off a little bit of this power for its own use from whichever plug happens to be connected to the battery. The negative pole of the battery is permanently connected between the plugs while the positive pole gets switched through the power relays.

The Deflator Valve

The controller contains a small, but powerful solenoid valve that can be opened electrically to facilitate deflation. Being a compact device in a confined space, it will heat up after being energised for a time. Air being released from the air hose will serve to keep the solenoid cool indefinitely, but the solenoid should not be kept manually energised for prolonged periods when no air is flowing through it.

Auto Mode and the Tyre Size Selector

Tapping the central green button starts an Auto Mode cycle.

The controller reads the hose pressure, which will be equal to the tyre pressure when the system is at rest, and the Target Pressure, which is set by the user, and decides whether inflation or deflation is required. The controller then reads the Tyre Size slider and uses its setting to estimate the time required for the deflation or inflation phase.

The App does not know, or does not take into account, the capacity or efficiency of the compressor, the state of the battery and whether it is being charged, or the condition of any filters and valve apertures which may be in the path of the airflow. The rate of deflation is largely determined by by the tyre valve aperture size and its depth of depression by the hose attachment ferrule. Also taken into account is that inflation will slow as the hose pressure rises, and deflation will slow was the hose pressure drops.

With this wide range of variables it is possible that a tyre may fall into two different categories when being inflated or deflated. The Tyre Size slider control can be set to five tyre sizes: very small, small, medium, large, and x-large. Each increment in Tyre Size category will produce approximately 30% more inflation/deflation time than the previous category.

The estimated time remaining is shown on the screen.

When the estimated time has elapsed the controller stops inflation/deflation for 5 seconds and then reads the hose pressure. If the hose pressure is within 5 kPa of the Target Pressure it terminates Auto Mode and beeps. If the difference between hose pressure and Target Pressure is greater than 5 kPa it recalculates and starts another cycle. This repeats until hose pressure and hence tyre pressure is within 5kPa of Target Pressure.
Setting the Tyre Size slider to too great a size will result in inflation or deflation overshooting Target Pressure and extra, avoidable cycles being required to reach the target.

Power Considerations

If you are using a compressor with some muscle – not one of those toys that plug into a cigarette lighter outlet and that get zipped into a little bag and kept under the seat, you’ll be connecting directly onto the battery with at least a 50 Amp DC Anderson connector. Most people would want to keep the engine running at idle to prevent unnecessary discharge of the battery while operating the compressor. The control unit can switch a DC current of up to 60A though the the Anderson connectors employed are only rated for 50A, which is current the limit of compressors that we support. Few 160L compressors draw more than 45A Max.

Under these circumstances there should not be enough volt-drop to the compressor to affect the operation of the remote control unit. If Bluetooth communication should fail while the compressor is drawing power it points to a connection problem that undoubtedly also inhibits proper functioning of the compressor and requires urgent investigation.

The cable between battery and compressor should have a cross-section of 6mm², which can carry a current of up to 56A and be limited to about 2 metres if possible. Spring-loaded clamps are not ideal for connecting to a battery – it’s advisable to make a short tail of 6sq/mm wires connected securely and permanently to the battery at one end and a 50A Anderson plug at the other.

The controller monitors the battery voltage as it is found supplied to the controller and transmits this value to the mobile phone, where it is displayed on the screen. Because small changes in battery voltage can be very significant in indicating battery condition it is important to get an accurate value reported. Since component tolerances can vary from unit to unit there is a calibration facility built into the mobile phone app to equalise these variances.

As a benchmark value: the voltage output of a healthy fully-charged battery after an hour at rest with no load will be 12,6V. As the battery ages this value will decrease through 12,5V 12,4V until at 12,3V the battery can be considered end-of-life since it’s capacity is half of it’s nominal value.

Battery Terminal Clamps

Battery terminal clamps on the end of the power cable make it easy to quickly connect to any vehicle’s battery, which is an advantage. The accompanying disadvantage is that intermittent short contacts are made which may involve some sparking.  The control unit is driven by a microcomputer that requires a steady power supply for reliable operation and is vulnerable to damage should the input power fluctuations overcome the very robust voltage regulation measures inside the control unit. Using battery clamps increases the possibility of control unit malfunction and should only be used in dire necessity, and then the battery clamps should be carefully attached to achieve the greatest possible contact area while the control unit is switched OFF.

Pressure Sensor Baseline

On first use the internal pressure sensor baseline needs to be established. This is always done at manufacture, but may in very rare circumstances need to be redone. (Such as when the controller firmware is upgraded and the memory is erased.)

With the hose input unconnected and open to the ambient pressure, hold down the Bluetooth icon at top left (the controller must be online) and then press the blue Hose Pressure indicator button until the phone buzzes briefly (this will take a second or less).  A command to zero the pressure sensor will be sent to the controller, and a toast popup message will indicate that the pressure sensor has been calibrated. No further action is required.

There is no need to adjust anything when transitioning from sea level to any other altitude since the pressure sensor measures absolute and not relative pressure.

First Use of Flashlight

Android requires the user to grant access permission to the app to use the flashlight. On later versions of Android this permission lapses after a period of time if the flashlight is not used and permission will again have to be granted. The app will be moved to the background by Android while this takes place and you will have to bring it forward again manually.


Control Unit Only – R2000
CU with Compressor, 10M Hose & Carry Box – R6000
The Above with Tyre Levers, Repair Kit & Backup Gauge – R7500

If you are interested in one of these awesome bluetooth inflator/deflator devices that could make your next off-road adventure stress free, kindly fill in the enquiry form below and the inventer will get back to you!

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    Disclaimer: Although the information shown above is presented in good faith and believed to be correct at the time of publishing, SA4x4 makes no representations or warranties as to the completeness or accuracy of the information. SA4x4 has no liability for any errors or omissions in the content freely displayed. Please note that all the prices shown below are subject to change without notice. Due to the nature of imported equipment shown above, please understand that we as a South African market are very dependent on the Rand/ Dollar exchange rates.

    SA4x4 encourages all patrons and users to check pricing of items shown online with vendors directly via our contact form.