Why Mobile Phone Remote Control?

 

• Mobility - a 30 metre range all around your caravan and total freedom of movement.
• Convenience - your phone is always at hand and the battery is always charged. Just switch on the controller and start the app.
• Safety -  You can be everywhere at once. No more accidental dings. 
• Voltmeter - Monitor your battery level while you work. Get a warning when the voltage goes low.
• Dual Select - Control 2 caravans from a single phone.
• Inch Mode - Take tiny single steps for final exact positioning.
• SoftStart current ramping for smooth, gentle starts.
• Electronic current limiting to protect your motors against overload.
• ComboTurns - automatic  differential power to outer and inner radius in a turn for 4-wheel caravans.
• MicroSpeed Control - 4 slide controls with pre-settable max power limit for really accurate control.
• A leveling guide to help you level your caravan.
• Built-in Flash - Use the phones flashlight for nighttime work.
• Backward Compatible - The switch panel works just like before.

Options: 

• Motor Temperatures - Monitor each motor's temperature. Motors are electronically protected against overheating.
• Water Flow - Monitor the quantity of water that has flowed from a tank through a flow sensor. Reset the quantity from the mobile's screen when you fill the tank or log the outflow.

• Caravan Leveler by remote control of powered corner steadies

The Remote Control Unit

 

Controlling ewiks:

The mobile phone as a remote control for ewiks as well as a general caravan mover remote control is an extension of the traditional switch-box ewiks control system. Connections are madein parallel with the hand-held switch panel so both systems are simultaneously functional. A set of drawings includinga block diagram overview and detailed schematics of the connections to be made may be downloaded here.

 

Installation is very simple: it involves: placing and securing the controller near to the existing ewiks electrical switchgear, mounting the power switch in a suitable place on or in the caravan's structure, and connecting  7 wires between the controller and the ewiks installation.. (See Power Considerations below).

 

Since the remote control relies on radio communication with the mobile phone for its operation, RF shielding should be kept to a minimum. The aluminium side wall of the caravan cannot be avoided and this by itself will not greatly inhibit the transmission of radio waves, but additional metal enclosures should be avoided.  

 

  

The Android Phone App

 

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 5.0 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.

 

Inch Mode

 

Tapping any motor button, or combination of buttons, while holding down the INCH MODE button sends a command to the Remote Control unit to energise the motor(s) for a single power pulse. This is useful when only small increments of movement are desired. A single power pulse will turn the drive drums through about an tenth of a turn, or 25mm (one inch) of movement, under no-load conditions. Under load this will reduce somewhat. A Red INCH MODE indicator is displayed while INCH MODE is active.

 

The INCH MODE button is placed to be convenient to the left thumb of a right-handed user. For left-handed operators the INCH MODE button can be moved to the right-hand side of the screen by tapping the red INCH MODE warning indicator when it appears. Use the same method to put it back on the left again.

 

Inch Mode is unaffected by Soft Start and works independently of it. Inch Mode is an alternative method for making small movements when SoftStart is not installed

 

SoftStart

 

This is a feature integral to the All-inOne MotorPac that gently ramps up the motor current over the first two seconds of any move operation, to make the start smoother and jerk-free. It uses solid-state electronic switching and a programmable oscillator in the microcontroller to smoothly add torque to the driive motors.

  

Combo Turns

 

Combo Turns are turns where, by holding down a single motor button (and the Combo button), both motors in a given direction are energised simultaneously, but the motor on the inside radius is given only 50% power while the outer motor receives full power. This feature is critical to turning 4-wheel caravans, but is also very useful with single-axles. Combo Turns can be made both left and right as well as forward and backwards.

 

MicroSpeed Control

 

On this screen there are four slide controls - one for each motor/direction Moving the appropriate slider increases the power to that motor from 0 to MAX* any slider returns it to 0% power output. Motor currents are still monitored and limits are still invoked to protect the motors from damage.

 

*The value of MAX can be preset for all sliders by double-clicking the DactylTech logo and moving the slider to the desired MAX power level. No slider will exceed that level. Double-clicking again saves that MAX for future use.

 

Motorised Leveling with Winterhoff Steadies

 

The App is also has remote control for a caravan leveler   The screen shows 2 leveling crosshairs which will centre when the caravan surface on which the mobile phone lies is level. Control for four leveling motors is provided on the same screen. The Leveling Controller support four bi-directional 12V DC motors with up to 25A of DC current. No limit switches are required as the controller senses end-of-travel and cuts the motor current automatically.

The mobile phonre is placed flat on a table and you tap the UP/DOWN pushbuttons to drive the corner lift motors until the dots centre on the crosshairs.

Leveling motors are supplied with ramped startup current and are automatically shut down when a current spike indicates that end-of-travel has been reached in either direction. Leveling motor current is diplayed on the screen of the mobile phone.

The motorising of the corner steadies is an easy DIY project available to anyone with moderate hand skills. See a step by step tutorial and video here.

 

Dual Water Tank Monitoring and Reporting

 

The Controller can monitor 2 Flow Meters and report the result on the screen of the mobile phone.  The flows are counted and recorded as long as the controller has power and will continue to count until reset. The tank capacity is entered at inception and the flowmeter is RESET when the tank is filled. Up to 200L per tank is supported.

Thereafter the display will normally show the percentage of capacity remaining, but can also show the actual numbe of litres used since the last fill (and reset).

Why Motor Protection is Important

 

An electric motor that is turning generates a bac EMF (Electro Motive Force) in proportion to its rate of rotation that limits the current that can pass through the motor. So a motor that is turning ( the faster the better) protects itself. Conversely, the slower the motor turns the higher will be the current flow and hence the heat generated in the armature windings. Should the motor stop entirely there will be a virtual short-circuit through the motor and the current will be limited only by the DC resistance of the conductors in the circuit, which for operating efficiency is kept as low as possible.

 

How to Protect Your Motors

Fuses

The cheapest but least satisfactory option. They are inaccurate and imprecise. And they are often awkward to get to and inconvenient to repalce when blown. Also, the fuse will protect against grossly excessive motor current, but it does not protect against the slow over-heating of a hardworking motor that does not actiually stall. Electric motors that that are staionary pass a very high startup current as described above which, though it might not actually blow the fuse, will heat it up significantly and bring it closer to blowing at the least provocation, such as the next inrush of startup current.

 

Circuit Breakers

Less inconvenient since they are re-settable and may be located more accessibly. But still not very accurate since their tripping current may be 30% higher than the rated current. The same concerns about heavy-load overheating apply. Circuit breakers are able to withstand high instantaneous currents such as occur when a motor starts from standstill without ill effects.

 

Electronic Current Limiting (CurrentGuard).

This is an extremely accurate protection with a very quick response, and it is self-resetting which means it requires no user intervention. Overheating due to a heavy workload may be slower to arise since the current is more accurately limited, but it can still occur.

 

Temperature Monitoring and Limiting (ThermoGuard).

As a low-cost final measure this gives protection against the destructive overheating that results from working the motors hard without crossing any critical boundaries that would otherwise shut them down. 

The MotorPac Main Unit and the X4 Tandem Axle Extension

Power Considerations

 

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. 

 

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.

 

Unless they are protected by electronic current ramping circuitry such as contained in our MotorPac series, electric motors tend to draw very high current when accelerating from a standing start. 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 if you do not have a MotorPac with current ramping:

 

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 assebly included with the controller should be connected between the batteries and the remote control unit and the switch is supplied with each wire tail labelled.

 

Displaying the Battery Voltage

 

The controller can meaure the voltage output of the main battery (the one used to power the movers) and display this value on the mobile phone's sceen. When the measured battery level is above 11.7 volts the background of the display is green, otherwise it is RED to indicate a potentially low battery condition. A battery can take several minutes to recover from a heavy discharge during which time the voltage output will slowly rise before stabilising.

 

As a benchmark value: we know that 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.

 

While discharging the output voltage of the battery will steadily decrease until, when about 90% of the available charge has been depleted, the voltage falls to the critical level of 11,7V. Most people do not want their battery voltage to drop below 11,7V because this is where the real damage occurs. Hard lead sulphate builds up on the surface of the plates and this permanently compromises battery capacity. Batteries can be ruined in a single deep-discharge event. To warn of excessive discharge the Voltage display will show a RED background when the measured voltage dips below 11,7V. Due to the internal resistance of the battery the output voltage does not accurately reflect it's stae of charge while it is being discharged (or charged). Therefore only measurements made while the battery is at rest are relevant.

 

Calibrating the Voltage Display

 

 In the world of lead/acid batteries small changes of output voltage can count for a lot. For instance 12,6V from a fully charged battery at rest is an indication of radiant good health, whereas 12,5V is cause for concern. Therefore it is important that the displayed battery voltage be as accuraate as possible.

 

Since slight variances in component tolerances can produce slightly different results and different units there is a calibration process that can be used to eliminate these variances. This needs to be done only once per phone because the calibration parameters are stored for subsequent relieval. The default value is an average one that meets most requirements. Because the voltage level is measured by instant snapshot any ripple from chargers or loads will show as a varying readout.

 

To enter calibration mode hold down the either Inch Mode button and double-click the DactylTech logo. The LB and RB buttons will disappear to be replaced by a Slider. Adjust the slider in small increment and allow a few seconds for the new voltage display to stabilise. When the display on the mobile phone matches that of a reliable voltmeter double-click the DactylTech logo again to save the calibration data and return to the normal screen display

 

Where DualSelect is implemented each selectable controller has it's own calibration data.

The MAC Address

 

In the Bluetooth Communications world the Master device (the mobile phone) needs to know the Media Access Control (MAC) address of the slave (the remote control unit). For security (to prevent others taking control of your caravan) the Caravan Mover app ( CM_2.apk)

 needs to be given the MAC address of the remote control unit, which is given on an attached label. To create the necessary record (or 2 if DualSelect is implemented) there is an easy-to-use app to download named MAC Editor. 

 

Download and install MAC Editor from the Menu above and use it to register the MAC address for Caravan Mover (and 2nd Caravan Mover if applicable. Once the MAC address(es) are saved the Caravan Mover app will have the means to form a Bluetooth connection to the controller(s). The MAC Editor may then be uninstalled.

 

The operation of MAC Editor is easy and intuitive, but for those that encounter uncertainty there is a dedicated page with detailed instructions here.