Theoretically, one horse power is defined as almost 746 Watt in standard calculations. Horse power is, therefore, an important unit of power. We are well aware of the use of the term horsepower in describing the powers of a motor used for pumping water from wells, cutting grass or sawing blades. The horse power (hp) is the unit of power which is widely used in the commercial field. We need to find the relation and solve to find the number of horse powers constituted by the given amount of Watts. It has some relation with the SI unit of power – Watt. The more significant way to compare is actual riding experience and battery range.Hint: The horsepower is a unit of power. The power rating becomes moot between the 2. If you compare apples to apples between Chinese ebike and German ebike, the 750 watt Chinese ebike may not be as powerful as the 350 watt German ebike. Additional efficiency loses occur at the drivetrain (gears, chains, derailer, etc.) Efficiency of electric motor is usually at the 80% (give or take) depending on load and speed. In reality, there is efficiency loss from friction and heat. Ideally, electrical watts is equivalent to mechanical watts. I remember Justin from ebikes Canada measured a 350 watt Bosch motor producing peak electrical output of 800+ watts. Non-Chinese brands : 750 watts equals 750 "sustainable" watts, plus it is measured as a mechanical watts at the output shaft (work / time or force x distance / time). The time during which the motor will work in throttle-only operation will be 600 Wh / 1071 W = 0.56 h = 33 minutes 36 seconds.Ĭhinese ebikes: 750 watts rating equals 750 "maximum" watts coming from the controller into the motor (volts x amps). We already know that the controller power demand is 1071 W. We know our 48 V battery is say 600 Wh capacity (the amount of energy stored). ![]() As electrically 1 W = 1 V * 1 A, the controller will draw this current from the battery: 1071 / 48 = 22.3 Amperes. Let us assume (for simplicity) the battery is 48 V. To deliver 750 W of power, the controller has to deliver 750/0.7 = 1071 W from the battery. Let us assume the overall efficiency is 70% or 0.7. Now, to deliver 750 W of power, the motor has to draw far more energy because there is the factor of mechanical and electrical efficiency nothing is perfect in this world. If the motor delivers 750 W, it will deliver 750 Wh or 645 kcal or 2700 kJ of energy during one hour operation. If power is delivered over some time, the energy delivered will be power * time. If your motor is 1 HP, it can deliver 750 W power or - in other words - 750 Joules of energy per each second. Watt or horsepower are the units of power, that is, the energy spent during a time unit. If your electric motor has efficiency of %80 then to produce 750W output at the crank you need 937W of input in the form of electrical power which is what you will measure by multiplying potential difference (measured in Volts) by the current (measured in Amps) at the terminals of the battery. In this case it is the proportion of the electrical energy converted into mechanical energy. Efficiency is the rate at which the desired conversion is achieved. So some of the electrical energy transformed into heat for example instead of mechanical power. Unfortunately conversions are not perfect, there are by products such as heat. ![]() In an ideal world to produce 750W of mechanical power motor would use 750W of electrical power. Your motor takes this electrical form and converts it to mechanical form and that moves your bike. Your battery stores energy in chemical form then it transforms it into electrical form. 750W refers to the measured mechanical power at the crank of the motor. Electrical motors are rated by their ouputs. ![]() What you write are not different types, they are simply examples which 1 watt of power is produced. ![]() it can be transformed from one form to the other. Energy can take different forms, mechanical, electrical, chemical etc. Watt is a unit for measuring power which is the rate of change in energy.
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