Electroprop Technology

Designing an electric drive of any given power level requires optimization of efficiency, power, cooling, and form factor.   Each of these four factors are inter-related.   Efficiency and Power increase with better cooling.   Form factor changes with the type of cooling.   What is required is a balanced approach to the fundamentals of electric design to provide the smallest, most efficient drive system for the power range required for your boat.

Each component has been designed in Solid Works.    Each of the renderings in our product offerings are generated from large computer files of every component, assembled in 3D.

We thoroughly research every component in each Electroprop Product to bring you the best solution for powering your vessel.

 

DESIGN PHILOSOPHY

Our design philosophy is Safety, Efficiency and Power.    Safety is paramount for obvious reasons.   Efficiency results in more net propulsive power.    Our drives have net efficiencies between 80 and 83%.     Power ratings reflect net consumed power.      Net Shaft Power is the result of multiplying consumed power by efficiency.

 

GEARING

All Electroprop products utilize gear reduction.     Reduction gears are necessary because electric motors create power by torque and rpm.   The faster the motor turns, the more net power it creates.    Yet propellers produce greatest efficiency at low rpms, necessitating speed reduction.     We choose gear reduction because gears have a small form factor, do not have any exposed moving parts, are self cooling, and have an integral thrust bearing which is cooled and lubricated by the gear oil.

The E-5, E-7 and E-11 utilize helical gears.   Helical gears are available in lower gear ratios necessary for the smaller propellers used on boats under 38 feet.    Helical gears can be run at up to 3,000 rpm, after which centrifugal forces through the oil off the gears onto the case.    Electroprop Helical Systems run between 1,900 and 2,500 rpm.

The E-20 and E-30 utilize planetary gears.   Planetary gears can run up to 6,000 rpm.   Electroprop Planetary Systems run between 3,500 and 4,500 rpm.

 

COOLING

Cooling is a prime consideration for each Electroprop Propulsion System.     Enhancing the cooling, enhances the power level and increases net efficiency.   The E-5, E-7 and E-11 are air cooled motors.    The E-20 and E-30 are both air cooled and water cooled motors utilizing radiators.   Fans on air cooled unit and pumps on water cooled units are switched based on the temperature of the electric motor.   This keeps the system at the highest possible efficiency at all times.

The E-5 needs no additional cooling.

The E-7 case has a high powered 9 inch fan mounted inches away from the electric motor, which draws air out of the E-7 case.   Air enters the case through ducts.   Two four inch ducts and one 6 inch duct are provided.   Ducts provide a means of air entering from outside of the motor compartment.    External air greatly increases power as the ambient air temperature of the cooling compartment stays cool and does not limit power.

The E-11 case has two high power 9 inch fans, one pushing air into the case, and one removing air from the case.   A 9 inch duct can be utilized to fetch air from outside of the motor compartment.

The E-20 is both air and water cooled.   The E-20 has water jackets in the thrust bearing plate, and the controller base plate and two water jackets in the motor.   The water is cooled by a radiator.   This eliminates potential corrosion by eliminating a second tie to ground found on units with heat exchangers.    The entire cooling system is constructed of aluminum with no other dissimilar metals.  This eliminates corrosion and the need for a motor zinc.   A 9 inch fan introduces air cooling into the case, and another 9 inch fan is mounted on the radiator and draws air away from the case.    A 9 inch duct can be provided if necessary to introduce external, cooler air into the motor compartment.

The E-20 is both air and water cooled.   The E-20 has water jackets in the thrust bearing plate, and the controller base plate and two water jackets in the motor.   The water is cooled by a radiator.   This eliminates potential corrosion by eliminating a second tie to ground found on units with heat exchangers.    The entire cooling system is constructed of aluminum with no other dissimilar metals.  This eliminates corrosion and the need for a motor zinc.   A 12 inch fan introduces air cooling into the case, and another 12 inch fan is mounted on the radiator and draws air away from the case.    A 12 inch duct can be provided if necessary to introduce external, cooler air into the motor compartment.

 

CONTROL SYSTEMS

All Electroprop systems come equipped with CANBUS throttle controls and a CANBUS Clearview motor and controller monitor.

On systems up to and including 48 volts nominal, battery negative is used as a reference on the CANBUS.   48 volts positive is not utilized at the key switch, thus eliminating having both 48 volt positive and negative wires at the helm.    The key switch is powered by 12 Volt DC to run a relay at the motor to turn on the controller.

On systems exceeding 48 volts nominal (60, 72, 84 and 96 VDC) Electroprop isolates all motor control systems.   This is accomplished with the use of a CANBUS isolator.

 

MONITORING SYSTEMS

All monitoring systems are completely isolated from Propulsion Battery positive and negative by utilizing shunts that convert battery status to information, at the shunt.

 

DC DISTRIBUTION SYSTEMS WITH GROUND FAULT MONITORING

Each new Electroprop now comes standard with a double pole main breakers with ground fault monitoring.    There are several safety and practical reasons for this choice of components.   Each disconnect breaker is rated for full system voltage with interrupt capacity greater than the short circuit current capability of the battery pack used.    This is done to prevent arcing which can lead to fire.

Each new Electroprop comes standard with Ground Fault Monitoring on the DC circuits.     The combination of double pole breakers with ground fault monitoring enables the floating of the battery pack (the negative of the battery pack is not tied to ground).    Should there be a ground fault on any circuit, double pole breakers isolate the entire circuit when switched off.    Isolation of the entire circuit allows for instant troubleshooting of the electrical system without the need for tools or expert assistance.

DC Distribution

DC distribution with 250 Amp Motor Breaker, Din Rail Accessory Breakers and Ground Fault Monitoring

A system that experiences one ground fault can continue to operate.   The ground fault needs to be rectified at the earliest possible convenience, but in the meantime does not interupt the operation of the vessel.

A system that experiences a ground fault on two individual circuits, will continue to operate provided that the ground faults are both to the same polarity.

A system that experiences a ground fault on two individual circuits on opposite polarity, will only be able to operate with one of the circuits at a time.

The utilization of floating battery systems provides for higher reliability, get home capability, and on board troubleshooting.   The likelihood of a ground fault is very low, however should one occur, this architecture is the safest and most reliable way of keeping your boat operational while apprising you of the situation so you can identify and deal with the fault as efficiently and effectively as possible.

Grounded systems lack all of the functionality described above.

Electroprop DC Distribution systems are fully enclosed in water resistant cases with no access to conductive metal surfaces.    Electroprop distribution systems are easy to install and provide safety unprecedented on marine electrical systems.   Electroprop DC distribution systems can be customized to exactly fit your boat.   Simply provide the lengths of the various cables and we will do the rest to make your system the ultimate plug and play installation.

 

AC DISTRIBUTION SYSTEMS

Electroprop’s packages come inclusive of Smart Power Shorepower Cord and Inlet.   Power is then routed through a whole boat ELCI breaker to the battery charger breakers.   All breakers are double pole.   All AC distibution systems come in water tight plastic boxes with no conductive metal exposed.    This makes the Electroprop AC distribution system the safest system on the market today.

 

RATINGS

Every Electroprop component is rated for full charging voltage experienced by the system.

 

PURE LEAD BATTERIES

Each Electroprop package comes with Thin Plate, Pure Lead, AGM Batteries as standard equipment.    Lithium is available on custom builds with professional installation.

Pure Lead batteries are more efficient than standard AGM batteries.   Pure Lead Battery cells do not short their cells at the end of their life making Pure Lead Batteries the safest batteries available on the market place today.    Pure lead batteries simply lose their capacity at the end of their lifetime.

 

PLUG-IN BATTERY CHARGING WITH MONITORING (AC SOURCED)

All batteries require charging management for long life, higher capacity throughout their lifetime, and safety.   The best way to accomplish these goals on a Lead Acid battery is to provide a dedicated battery charger for each battery, with a temperature sensor on that battery.    Without management, a battery system gets more out of balance on each charge, which results in premature failure of the battery pack.    Our standard 25 amp smart battery charger measures the voltage and temperature of the battery and broadcasts that information over the battery management screen.    Additionally, voltage is alarmed on high voltage and on low voltage.

Individual battery charging allows for the replacement of any one battery in the string, without having to replace the entire string of batteries as is necessary on blind systems.

Blind Battery charging systems charge at full pack voltage without any monitoring or control over the individual batteries.   In these systems, every battery shares the charging voltage with all the other batteries.   Since batteries vary in resistance, the higher resistance batteries start stealing the voltage from the lower resistance batteries during charging.   This results in overcharging the weaker batteries, and undercharging the stronger batteries, thus prematurely destroying all the batteries in the pack.    Blind battery charging systems can not do individual battery temperature compensation and cannot stop charging if one battery in the string goes thermal, which leads to serious safety issues.   Batteries in blind systems can get so hot they burn or explode.    Obviously, we do not recommend blind battery charging systems.

Battery Charging from an Plug-In source is a power distribution challenge in that power is distributed from one source to multiple batteries.    The practical reason why we chose a charger for each battery is because it is easier to distribute power through AC than it is through DC.   AC is easier to control and simpler to distribute.    DC charging requires balancing during and sometimes after charging.    Dedicated battery chargers are able to do accurate temperature compensation.   Dedicated battery chargers can observe algorithm timing specific to the individual battery which results in longer battery life and higher capacity throughout the battery life.

I have seen standard AGM batteries fail within 2 years while practicing as a marine electrician and the culprit was almost always the charging system of the batteries, though deep discharges are also a prime reason for premature battery failure.    Conversely, on my own boat equipped with a balancing system, the average life of Kapowai’s batteries was 10 years.   The logic behind purchasing dedicated chargers is financial as well as for reliability.    A good charging system will pay for itself over time, with returns starting in as little as two years over a blind system.

Each of our plug in systems can accept our hybrid charging controller set to be released late Summer 2016.    Our hybrid charging controller utilizes individual battery information to prevent over charging of the batteries by DC generator or other DC charging source.

 

RENEWABLE ENERGY CHARGING (DC SOURCED)

Each Electroprop Renewable Energy System comes standard with battery balancers.    Balancers shunt up to 200 milliamps between batteries to keep all batteries at the same voltage.   This extends the battery life, and capacity throughout the life of the battery bank.

The balancers have the added function of monitoring the battery bank.   In the event that the shunting current is unable to compensate for the weakening of a battery, an alarm contact trips.   We use this alarm contact to run a relay with audible notification and to disable all charging sources to prevent a thermal occuring on any one battery.

 

PLUG-IN AND RENEWABLE ENERGY CHARGING

To accomplish both Plug In (AC) and Renewable (DC) charging on our ALL ENERGY Packages, we disable the Battery Balancers when AC is present so balancing does not affect the charging algorithms of the chargers.

 

CONCLUSION

Electroprop technology provides efficient power for your boat while observing all pertinent safety issues.   We have the experience to know how to build systems that are powerful, easy to install, safe while providing you with the information that you need to make informed decisions at sea.    Our systems are more expensive than most other systems on the market, with the returns of your additional investment becoming apparent very quickly after your installation.     This makes Electroprop technology the highest value on the market for your propulsion and energy needs.