The MotorPac Comprehensive Motor Control.
Available Extensions:
- Levelling Extension Levelling Extension
- VanSecure LPG Gas & Intruder Alarm Extension VanSecure Extension
- LPG Gas Weight Monitor LPG Gas Weight
- Water Flow Sensor Water Tank Monitor
- Tow Ball Weight Measuring Tow Ball Weight
- Dual Digital Thermal Probes Temperature Monitors
- X4 Tandem Axle Extension (On this page)
The standard mover control switchgear as supplied by ewiks is limited in some respects. It can switch current to the motors effectively but that current is switched either fully on, or fully off - nothing in between. This means that caravan starts and stops will always be abrupt and jerky. Also dual axle caravans are at a disadvantage because turns are made with the motor(s) on the outer radius under full power, and the motor(s) on the inner radius standing still. The inner wheels therefore are dragged laterally across the surface, under great friction and with some damage possibly done. The Motorpac comprehensive caravan mover control electronics are able to modulate the power supplied to the motors.
Soft Start
Soft Start caravan mover control is a feature integral to the MotorPac Comprehensive Caravan Mover Control 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 drive 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 pre-set 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.
In Summary the MotorPac Contains:
- Remote control unit for mobile phone control
- Dual 32A Circuit Breakers (30A per motor node),
- 4-Relay motor direction control,
- Soft-Start current ramping,
- Combo-Turns radiused turns with differential motor power,
- Micro-Speed Control on all motors, variable from zero to a user-determined limit - 100% Max
- Battery voltage Monitoring and reporting,
- Current-Guard motor current monitoring and electronic limiting to 30A,
- A 5-pin XLR socket for backup manual switches.
Available Extensions:
- X4 Dual Axle Control,
- Levelation levelling controller,
- Van-Security LP Gas & 4 Zone intruder alarm unit,
- Water tank flow meters to monitor two water tanks,
- LPG gas cylinder weight monitor,
- Tow bar weight sensor,
- Digital Thermal probes,
- Battery Voltage Display
See the MAC Address section: Set MAC Address
MotorPac X4 - Tandem Axle Extension
Four-wheel caravans 2 need additional motors driven by power switchgear that works in sync with the primary equipment. MotorPac X4 provided what is needed - a dual 32A circuit breaker, 4 motor direction relays, and Soft-Start current ramping with Combo-Turns that harmonises with the primary axle. Current-Guard protection afforded to the first axle is duplicated with the tandem axle. Heat sensors are only applied to one axle as the temperatures are assumed to be similar on the tandem.
MotorPac X4 has its own housing which is placed in close proximity to the main MotorPac, its own 50A Anderson power input, four motor output wires, and a signal cable to control all functions.
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 replace 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 actually stall. Electric motors that that are stationary pass a very high start-up 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 start-up current.
Circuit Breakers
More convenient 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 (Current-Guard).
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.