Electric boating is gaining popularity, thanks in part to advances in technology and growing awareness of environmental impacts. However, for many enthusiasts looking to make the switch, the technical side remains a challenge. Choosing the right battery voltage for your electric vessel is crucial for optimal performance and safety. But what exactly is the "right" voltage, and why does it play such an important role?
Power (expressed in watts) is the product of voltage (volts) multiplied by current (amperes). Ideally, designers of electric propulsion systems for boats keep the current below 300 amperes to ensure safety and efficiency. Yet, there's a trend where some systems exceed this preferred threshold to reduce costs, as lower voltages are often cheaper and seem safer. This can lead to systems that may appear cost-saving at first but might compromise on safety and reliability. While lower voltages might enable some users to perform installations themselves without a qualified electrician, it also carries risks. Non-professional installations can lead to errors that jeopardize the system's safety and reliability.
As the desired power increases, raising the voltage is the most efficient path. This keeps the current within safe and manageable limits. Higher voltages require relatively thinner cables and minimize heat development, leading to higher efficiency and a longer lifespan of the system. A key reason is that a doubling of the current in connections leads to a quadrupling of heat. Repeated expansion from heating and contraction from cooling can cause connections to loosen. Loose connections increase the risk of higher resistance points, which in turn generate more heat. This creates a vicious cycle that can result in decreased performance, malfunctions, or more severe safety risks like short circuits or fire.
With higher voltages to keep the current manageable, professionalism in installation and maintenance is crucial. This ensures not only the correct connection of the system but also compliance with all safety standards. In the design of electric propulsion systems for boats, especially those using higher voltages, a developer is almost forced to thoroughly consider security. This ensures that advanced safety options are an essential part of the system design, protecting both the user and the system. Here are some examples of core aspects integrated into modern systems:
Insulation: Essential for preventing unintended electrical conduction, insulation provides protection against electric shocks and minimizes the risk of short circuits.
Floating systems: By having no direct connection to the earth, floating constructions minimize the risk of electric shocks, contributing to a safer system.
Insulation monitoring: This system continuously monitors the integrity of the insulation. Upon detecting a decrease in insulation quality, for example, due to wear or damage, the system can alert or take preventive measures to avoid accidents.
High Voltage Interlocks (HVIL): HVIL systems ensure that high-voltage components can only deliver energy when everything is correctly and safely connected. This prevents the risk of electric shocks or short circuits with incorrect connections. If a part is not correctly connected or there is a defect in the circuit, the signal is interrupted, and the system detects this as an open circuit. This immediately activates the HVIL, interrupting the power supply to the high-voltage components to prevent damage or injury.
System 1: 10kW at 48VFor small to medium-sized boats, where a calm cruise is desired, a 10 kW system at 48V provides an ideal solution. This system, with a relatively low voltage, keeps the current below the safe limit of 300 amperes. This type of motor is comparable to a 20hp diesel engine.
System 2: 28kW at 96VFor those who need more power, for example, for longer trips or for sailing with larger boats, a 30 kW system at 96V offers an excellent mix of power and safety. A voltage of 96V is considered a medium-high voltage, which means that the components require less specialized demands than systems operating at higher voltages, such as 350V. This makes it not only technically more accessible but also more cost-effective.
System 3: 90 kW at 350VFor large displacement yachts and professional applications, a 90 kW system at 350V is a good solution. This system keeps the current well below the 300 ampere limit, drastically reducing the risk of overheating and inefficiency. With such high voltages, advanced safety measures such as HVIL (High Voltage Interlock Loop), insulation monitoring, and floating constructions become essential for user safety.
Choosing the right voltage for electric boating is a delicate balance between power, efficiency, safety, and cost. By increasing the voltage at higher power, currents can be kept manageable and safe. This leads to more efficient systems with a longer lifespan and less risk of overheating or accidents. If you're considering making the switch to electric boating, it's essential to be well-informed and advised about the best voltage choice for your situation.
