How much is enough boat electric motor: real numbers and calculations

The question of how many hours or kilometers of power a boat electric motor will last is the most popular among anglers and small boat owners, and the answer cannot be a single number, since the operating time depends on a variety of variables, from battery capacity to weather conditions. Electric tractor It is radically different from gasoline analogues by its predictability, but requires a competent selection of the motor-AKB bundle.

Unlike an internal combustion engine, which consumes fuel unevenly depending on the load, electric motor It has a very strong correlation between the current and the speed, and if you're planning to use a boat to troll at low speeds, you can have a single charge for a whole day, but when you're driving at maximum speed, you're going to have a much shorter operating time, which is often a bit of a surprise for beginners.

In this article, we will analyze the physics of the process, consider the real indicators of various models and learn to calculate the results of the study. autonomy Understanding these processes will help you avoid situations where the coast is a few kilometers away and the battery has already run out. Proper operation It starts with a theory that we will now look at.

Process physics: traction, speed and energy consumption

The basic law governing the operation of an electric motor is that the higher the thrust, the more current the motor consumes. However, this dependence is nonlinear. When you go from the first speed to the second consumption, it may increase slightly, but going from the penultimate to the maximum speed often doubles the energy consumption. Efficiency of the screw The battery also plays a critical role.

Many owners mistakenly assume that a motor with a power output of, say, 55 pounds of thrust will consume 55 amps per hour all the time. It's not. At low speeds, the consumption can be as low as 5-10 amps. Nominal traction This is the maximum level that can be achieved under ideal conditions and full gas.

• 🔋 Current consumption at 1-2 speeds is usually 10-20% of the maximum.
• 🌊 Headwind or current can increase energy consumption by 30-40%.
• ⚓ Overloading the boat (overweight) reduces the efficiency of the screw and increases the discharge.

⚠️ Attention: Using the motor at maximum speed for a long time can lead to overheating of the windings and a sharp drop in voltage at the terminals of the battery, which the electronics will perceive as a discharge.

To understand the actual numbers, it is important to consider that voltage The currents of the system (12, 24 or 36 volts) are affected, and with the same motor power, the increased voltage reduces the current, which reduces the loss of wires and the heating of the system, which is especially true for high-power models.

Types of batteries and their effect on the range

The heart of your power grid is a battery, which is responsible for 80 percent of your success in swimming, and standard starter batteries designed to start a car's engine are not designed to run a motor for long periods of time, but to deliver a hugely designed current in seconds, not to give it a uniform output of energy for hours.

The best choice is traction batteries, in particular technology. AGM, GEL modern LiFePO4Lithium-iron-phosphate batteries, despite the high price, allow you to use up to 95-98% of their capacity without harm to chemistry, while lead analogues recommend discharge by no more than 50%.

Consider the comparative table of different types of batteries with a capacity of 100 Ah at a discharge of 25 A (conditionally the average speed of the motor):

Choosing. feed-in, always look at the C20 or C100. It's a 20-hour or 100-hour discharge capacity. If you say 100 Ah on a battery, it doesn't mean it's going to give 100 amps per hour. At high discharge currents, the real capacity of the lead batteries drops (the Payckert effect), whereas lithium keeps the volume pretty much the same.

Calculation of working time: formula and examples

To know how long your battery will last, you need to do a simple math calculation based on Ohm's law and knowing the capacity of your battery. Time (h) = Battery Capacity (Ah) / Motor Consumption Current (A).

But as we've already seen, the current changes, so it's more accurate to do the calculation for a particular driving mode, like you have a 30 lb motor with a 30A maximum and a 100 Ah battery (AGM) and we're allowing a discharge of up to 50 percent, so we're using 50 Ah.

Calculation for different regimes:

• 🚤 Maximum speed (30A): 50 Ah/30 A = 1.6 hours (about 1 hour 35 minutes).
• 🐟 Trolling, 3rd gear (10A): 50 Ah/10 A = 5 hours.
• 🍃 Minimum speed (5A): 50 Ah/5A = 10 hours.

⚠️ Warning: Never plan your route using 100% of your estimated time. Always leave a 20-25% margin for unforeseen circumstances, such as increased winds or manoeuvring.

For more complex systems with 24 or 36 volts, the calculation is similar, but takes into account the total capacity of the battery bank. If you have two 100 Ah batteries connected in series (24V), the capacity remains 100 Ah, but the voltage doubles, allowing the motor to work longer at the same power.

Factors that reduce the operating time of the electric motor

Even an accurate calculation can fail if external factors are not taken into account. Ambient temperatures are one of the main enemies of lead batteries. At 5°C, battery capacity can drop by 30-40% compared to summer levels. Winter fishing requires special measures to insulate the battery.

The state of the propeller also affects efficiency: If the blades have chipped, burrs or they grow with algae, the motor will work with increased load, consuming more current to achieve the same speed. propeller It's mandatory.

The second tip is navigation. Try to plan your route so you can go against the wind or the current at the beginning of the fishing trip while the battery is full. It's easier to come back in the tailwind when the charge is already half-dried out. That's the golden rule. water-motor.