Star Investments company started first tests with electric drives in 2004. Our experiance showed that attempts with standard electric drives do not come in pair with appriopate results. After many attempts and tests Star Investments decided, in cooperation with german engine producent, to elaborate a totally new electric drives, especially for vessels. The core of the system is produced in Germany, electronically controlled, brushless (BLDC), water cooled and completely maintanance free electric drive with voltage from 36V/48V/60V and 80VDC and power from 2,2 kW to 20 kW.
Taking in account, working conditions for these kind of engines, like small closed engine bays, the most fragile components to thermal heating with electronic controller on top, are water cooled in closed circuit.
Cooling system is based on heat radiator, made of stainless steel water cooler, electric pump, reservoir tank and few other components.
Thanks to this solution, engine, and mainly it's controllers, are maintaining constant work temperature, eliminating the loss of power effect which goes with the increase of temperature. According to that, our engines can work on very high workloads for a long time. E-TECH electric drives are equipped with number of thermal sensors, which in case reduce the power and allows for a safety way back to the coast.
The biggest advantage of our system is the engine speed and torque which under load is about 1200 to 1500 RPM, which means that is the perfect speed for the propeller. It eliminates the need of use any reducer shafts. Taking into account the need of drive transmission, we mount in our engines special bearing which eliminate any other bearings on drive shaft.
We can find few more offers of electric drives on the market but on these moment, E-TECH system seems to be the best for vessels. This is mainly due to the fact, that all other systems are based on standard producted engines. These systems have very adverse voltage to torque ratio. On average they need 1V for 50-70 RPM. It is easy to calculate that with 48V, the engine speed oscilates in the range of 2500 to 3500 RPM. Without proper transmission shaft it is impossible to operate that kind of engine with typical propeller, which complicates all the system.
Tranmission shaft, not only reduces the power, but also generates additional maintanance cost and necessity to manage bigger space, how valuable, under the deck of any vessel. Next drawback is the air cooling system and related with that very strong heat emission and loss of power. At a glance, the RPM problem, seems to be easy to solve. The voltage must be reduced to 36V or even 24V. In theory it is of course true, but we must remeber that as far as we reduce the voltage, the amperage must be higher wich effects in siginificantly faster battery discharge.
We will use the following example. In order to get 2,5 kW of power, engine with voltage of 24V needs current with amperage of 110A, while an 48V engine will need only 50A. Going on, the higher battery discharge current, the lower it's real capacity. It means that, a battery with a capacity of 230 Ah with discharge current 110 A shows real capacity of about 180 Ah, which means only 1:30h of battery work. With the use of 50 A, boating time will increase to about 4:30h, which is almost three times longer.
From the physics point of view, solution proposed by Star Investmens, seems to be an revolution in the field of vessel electric drives. Tests were conducted in cooperation with reputable Norwegian shipyard Polar Boats. After mounting E-TECH 6 on yacht Polar 22, 7m long and 1,5 ton of weight, test vessel was lanuched on the river and the fun part started. With average speed 8-9 km/h (about 5 knots) we obtained endurance of 8 hours on the standard set of batteries with capacity of 230 Ah. We were also suprised with very good work perfromance on low current, outstanding our expectations. With the amperage of 5A, our test boat, obtained about 5,5 km/h (3 knots) of speed. E-TECH-6 system is designed for vessels up to 10 m long and weight to 4 tons. It can be also powered by from sun batteries or yacht wind generators. It can also act as a generator and charge the batteries when you are sailing.
Currently, Star Investmens is producing a wide range of E-TECH electric drives with power from 2 kW to about 20 kW. Our electric drives are maintenance free, additionaly the producent provides a complete kit, where you can find also an electronic power lever, ignition, main fuse and also all the required electrical and water wires. All of the parts are numbered and labeled which significantly simplifies the engine assembly. Electric drives, still not so popular , are the only solution for sailing in quiet zones. Undeniable advantage is also the negligible operations cost, comfort, safety and ease of use. Not without significance is also fact that our electric drives are very environment friendly, do not polute air or startle animals.
New Tests in Germany : http://www.fodiator.de/Bootsantrieb_Brennstoffzelle.html