The ewiks System
The ewiks Caravan Mover is a well-designed wheel-driving system using effective motors and effective traction drums. It is widely used by many caravan owners and greatly respected. I spend two thirds of my time in a caravan and greatly appreciate the mobility that ewiks affords me. The ability to effortlessly manoeuvre the caravan for position and privacy is invaluable and not something I would want to be without.
I developed the mobile phone remote control primarily for my own use and found it enhances the ewiks experience by 100%. To be able to move freely around the site and edge the van to exactly the right spot, using a mobile device that is never further away than my shirt pocket is a delight, and the family jostles for the pleasure of using the control. I now offer it selectively to discerning ewiks users who want to get it exactly right..
The remote control unit is more expensive than the garage door-type radio devices because it employs the very sophisticated Bluetooth system, which requires extensive processing power to implement. The advantage of harnessing a mobile phone to this purpose is that it is always to hand and the battery is always charged.
The controller energises all legal combinations of 4 output relays that duplicate the functions of the switches on the handheld control panel. The functioning of the handheld remains unchanged. Connecting the controller to the existing installation is a simple matter that can be undertaken by anyone Installation of the Android phone app is detailed on a Connecting page on this website.
Step 1: The MAC Address
This page which can be reached here or in the Menu above describes the step by step procedure for creating and editing a MAC address. The Caravan Mover app is designed not to run if no valid MAC address is available, since there is no possibility of successful connection under these circumstances. Earlier versions were able to run on a generic MAC address but this led to ambiguities. Hence the first step required is to create the correct MAC address to connect to the remote control unit. The Caravan Mover app may then be downloaded and run even if no Remote Control is available.
Should you wish to evaluate the app you can create a dummy MAC address, but be sure to entirely remove the app from system RAM before restarting on the correct MAC when you receive it. The app reads the sddress only once: at program start.
Provides all the facilities of the hand-held switch panel as well as allowing mobility all around the caravan to be manoeuvred into position. Phones running Android 4.2 and higher are supported. For convenience the app never goes to sleep, but remains active on the screen until it is shut down, and when it is shut down the Bluetooth connection will be broken.
There is a flashlight button to let you illuminate the scene should you be making camp after dark.
Unlike many mobile phone apps this one is fixed to the portrait display orientation, and will not blank the screen after a certain time. Care should be taken when pocketing the phone while the program is running since buttons may be pressed unintentionally. The app can be put to sleep with the power button and restored the same way. On awakening it will need to re-connect, and will attempt to do so automatically.
The Basic Remote Control Unit
The Mobile Phone App with no Current Measurement and Control
Positioning the Switch Panel
The power switch panel should be located convenient to the doorway where it can be reached from outside, and in a place where it will not be inadvertently actuated. The switch panel at right is able to switch both batteries to supply the controller with raw as well as clean power and also float-charge the secondary battery when the system is switched off.
The panel needs a hole cut in the wooden wall of the dinette seat (easily accomplished by just drilling a row of adjoining holes), for which purpose a cutting jig is provided which has the same footprint as the panel.
A convenient place to place the controller is on the underside of the tip-up lid of the dinette's seat since the ewiks switchgear is often located inside the compartment as well. If a secondary battery is implemented the negative pole should be connected direct to the negative of the main battery, which is often also located under the seat of the dinette, with wire of at least 4sqmm.
Since none of 7 wires connecting the controller to the ewiks equipment will carry more than 1 Amp of current the wire can be of the single-strand telephone type. Wire connections to the ewiks circuitry can be made either behind the female trailer plug, or at a spot closer to the ewiks switchgear. The schematic shows the ewiks norm, but you should confirm that your caravan conforms to this standard before switching anything on.
The wires extending those attached to the switch panel should be similar to the tails already there. See the schematic which can be downloaded here, and the Power Considerations section below, for more about the optional second battery..
The app is easily installed in just a few minutes by following instructions on the Connecting page. It permits the same directions of movement as the hand-held panel but extends the control range to approximately 50 metres from the caravan. Before the app can be used you need to set the correct MAC address using the MAC Editor, an app also downloaded from the same page. The MAC address is a 6-byte number that uniquely identifies a Bluetooth device.
Should the mobile phone go out of range the motors will stop within less than half a second.
The Switch Panel Conveniently Located
The Mobile Phone Remote Control unit requires a 12 volt power supply similar to that which powers the rest of the caravan. It draws a current of about 200mA while working. The cheapest and simplest way to supply it with power is to connect it to the caravan's battery system through a single-pole on/off switch. But there are ramifications to consider. Download the schematic here
When a motor car's battery approaches the end of its life, typically after four years of work, it is easy to read the signs - there's not enough power available to crank the engine to life, but the usual load on a caravan's battery is so slight that it is a lot harder to recognise any degree of deterioration - a few low-energy lamps and an intermittent 3 Amps to the fridge can be supported by the most feeble battery. Thus it can come as an unwelcome surprise that the existing battery has become too weak to deliver large the large currents demanded by powerful electric motors for extended periods of time, such as when positioning a caravan into an awkward spot.
It is in nature of electric motors to draw a very high current during the short interval it takes the motor's rotor to come up to speed from standstill. Once the motor is turning that very movement resists excessive current flows and the current will only increase when the motor encounters increased resistance. This means that any time a motor is started the battery output voltage will dip momentarily before recovering. As the battery becomes increasingly discharged these dips will go lower and lower until the regulator serving the remote control unit is unable to supply a continuous stable voltage. At this point the controller will disconnect its communication with the mobile phone and everything will stop. Caravans are often equipped with deep-cycle batteries which are less suited to delivering large the electric currents that are demanded by electric motors under heavy load than the cranking batteries found in cars, thereby aggravating this potential problem.
There are two solutions available:
1. Connect the trailing mains-cable to the caravan's power input before and while you use the ewiks motors. This will greatly reduce the power dips and help to keep the battery from discharging too deeply, especially if you keep the duty cycle low. To power the remote control unit from the main battery connect the bridge as shown on the schematic.
2. Power the remote control unit from a separate, dedicated supply battery such as a 12V gel-cell of the type used in burglar alarm systems. The gel-cell will keep the remote control powered for many hours, but not indefinitely. When the power switch set to Off the main battery (and its charger) will be connected to the secondary battery to keep it float-charged. The schematic details how the 2-pole switch should be connected between the batteries and the remote control unit and the switch is supplied with each wire tail labelled.
Refer to the Troubleshooting page from the menu at top in case of difficulty
Radio Frequency (RF) Shielding
All sheeting and mesh that is made from electro-conductive material will hinder the propagation of radio waves to some extent. The more enclosed the communication devices are by metal, the more the effective communication range will be reduced. Many caravans have side walls that are clad with an outer skin of aluminium that will introduce limited shielding. However they also have floors and other panels made of wood, plastic roofs, poly carbonate windows, plastic wheel-arches, and fibreglass end-caps that are permeable to RF radiation.
Bluetooth communications use the 2.485GHz frequency band which means that the transmission path is entirely line-of-sight. The placement of the control unit therefore influences the range and reliability of radio contact with the mobile phone, bearing in mind that the propagation path will vary as the operator moves around the caravan and the degree of shielding changes. Since the control unit continually returns a status message to the mobile phone (see left and right), the mobile can display the current relay status. It does this by superimposing an arrow over the activating button when the corresponding relay is energised. The unit need not be fully installed in order to determine the suitability of the intended location - it only requires 12V and Gnd to be connected. When Bluetooth is interrupted for more than 4 seconds this is reported by onscreen message and the blue rune at top left turns to a red alarm. Tapping the alarm symbol initiates a reconnection attempt.
The time invested in testing the comparative suitability of the various available installation locations will pay large usability dividends in the long run. Spots near the door, which can be left open during caravan positioning, in sight of windows, near the floor, or close to the end-caps or wheel arches will be more suitable than near sheer walls of metal. In most cases RF shielding will not be a significant problem but it is always good to know beforehand if there are any weak reception spots around your caravan so they can be avoided when using the mover.
We have found that single skins don't reduce Bluetooth range to less than about 20 metres, but when the radio signal is expected to pass through multiple layers of metal significant losses can be experienced.
Left Forward, Right Backward engaged
Right Forward, Left Backward Engaged
Custom made plug that carries 2 pairs of wires to the circuit breakers
Custom-made plug that takes the place of both 30A fuses. Yellow coded 6,3mm crimpable spade lugs are pressed into the holes. The block is then secured with the existing thumb-screw. From the crimp lugs wires carry the current to the circuit breakers and back.
Eliminating the Fuses
The Power-to-Weight Ratio of the ewiks motors is quite low - a fraction of a KW to move more than a 1000 Kgs of caravan and, despite very low gearing, under sufficiently adverse circumstances the resistance of the caravan can overwhelm the motors and bring them to a complete halt. When this happens the current through the motors will shoot up to a potentially damaging level and the protective fuse will instantly blow, protecting the motor but rendering it inoperative until the fuse is replaced.
The fuses are not expensive and easily replaced, but access to the fuses can be awkward since they are located on the top of the electrical control unit which may have been installed in an inaccessible place. Also, replacing the fuse does not remove the obstruction that cuased it to blow, and if this is not found and eliminated successfully the new fuse will just blow again, leading to a potentially annoying situation.
A low cost and easy to implement alternative to fuse protection is a pair of domestic-type circuit breakers. To avoid the need for major surgery on the existing wiring this change uses a custom plug, made on a 3D printer, inserted into the sockets that currently accept the fuses .You never need to replace a fuse again! No change is required to the existing hardware and reversion to the old system takes just a few seconds.
You can do this yourself with items stocked by your local hardware shop. The plug body can be fashioned from a block of nylon and some accurate drilling, and secured with the existing M4 screw, Use 6.3mm yellow spade lugs crimped onto 4 sq/mm auto wire, which is rated for currents up to 35 Amps. (Auto wire is difficult for circuit breaker connector clamps to hold on to unless some plastic sleeve is also gripped in the clamp).
Electronically Prevent Overloading
A futher (and more costly) remedy available is inserting a pair of Hall Effect current sensors into the circuits feeding the motors to continually monitor the electric currents through them, and allow the Remote Control to interrupt current to either motor whenever this reaches the 30A limit. The Remote Control will attempt to reconnect repeatedly, and disconnect again if the problem persists. At this point the button on the mobile phone should be released and the cause of the overload attended to,after which the move can be resumed. This is an add-on to the circuit breaker system described above and so requires no modification of the standard ewiks installation.
The schematic for the CurrentGuard module may be downloaded here
As an information aid the Remote Control transmits the prevailing current measurements to the mobile phone where they are displayed on a colour-coded backgound. Green for up to 10 Amps, yellow up to 20 Amps and red above 20 Amps.
The Remote Control measures the current flow 10 times per second but, for readability. reports these values on the mobile phone only once per second. Even so there is often more information displayed than can be easily taken in. To record significant events for later analysis you can take a series of sequentially-numbered screenshots simply by tapping either amperage display button. The screenshot is stored in a directory named CM_SS which is found in the System Root. Any file explorer can be used to find this directory in the Root of the Internal Storage and display the screenshot files saved in it. A new sequence is started with every session of the app and old files are overwritten automatically.
Two domestic 32A circuit breakers located near the ewiks electrical controls
The motor current values are received and diplayed with a colour-coded background. Seen here the left-hand motor approaching the cut out threshold, but will be disconnected before tripping the circuit breaker or overloading the motor.
The Handheld Switch Panel
The remote control unit is often more versatile and convenient to use than the handheld panel, but it does not replace it entirely. There may well be occasions when the remote control is not available or not able to do its job, and at these times you will want to revert to the handheld switch box.
Great care should be taken that both the remote control and the switch panel are not used simultaneously, since conflicts might arise from a motor being switched in both directions at the same time, which will result in the fuse for that motor being blown and requiring replacement.
Keeping a stock of 30A fuses on hand is always a sensible precaution as they are prone to blowing any time a motor is pushed to the limit of its torque, such as can happen when operating in soft sand, and especially when the jockey wheel becomes mired.
Price - R700.00
Includes controller, switch panel, some connecting cable, WhatsApp and email support.
Excludes batteries, Current Limiting Extension and shipping charges.
You will need additional wire, connectors, and general mounting hardware, depending on your particular installation.
Current Monitoring and Protection
Includes 2 x 32A circuit breakers, dual circuit current monitor, fuse replacement plug, wire and crimp lugs. R600.00
PostNet offers a counter-to-counter service for R99 that takes 2 to 3 working days, and this is what many people opt for. Delivery to your door is available from PostNet at additional cost.