In fact, direct drive motors such as the Nine Continent are often listed as 500 or even 1,000-watt motors, but many people have had success running them at over 3,000 watts by drilling out the cover plates to offer extra air cooling to the motor. Other modifications like increasing the gauge of the cables carrying power to the copper windings can greatly maximize the helpful power output of those strong, underrated motors. Is it okay for ebike companies to rate their motors this way? Technically yes, even if the amounts are accurate. But most of the time a”250 volt constant” motor may handle over 250 watts continuously, meaning the numerical naming convention is wrong and misleading.
WHAT’S A WATT?
A 500 watt electric bike conversion kit may be listed as a 500-watt kit, yet a closer review could demonstrate that the kit includes a 48V battery plus a 20 amp summit control. The mathematics shows us that this kit is in fact capable of putting out 48V x 20A=960 watts 1,000 watt kit. What might have originally appeared to be too feeble (promoted as 500 watts) is an around 1,000 watt peak kit, perfect for our 220 lb rider we utilized in the case around over. Watts may be used to assess the instantaneous power output (or input) of a machine, such as the electric motor on your ebike.
The number of watts used by an electric motor at any time equal the voltage supplied by a battery multiplied by the current flowing from the battery to the engine. So an ebike motor attached to a 24V battery being provided with 10 amps of current would be powered at 24*10=240 watts. This is where things become complicated however, because ebike makers don’t always rate their components this way. When comparing ebikes or ebike kits, then it’s crucial that you understand firstly if you’re comparing constant or peak electricity. Whenever someone advises that a 220 pound rider would likely need at least a 1,000 watt motor, he or she generally means 1,000 watts of peak power, as in the amount of electricity the ebike ought to have the ability to produce to push the rider up a hill. How do bike manufacturers eliminate this?
One means is to speed the engine to get”continuous power” instead of”peak power”. The difference between constant power and peak power is that continuous power essentially means power a motor can safely manage for an indefinite quantity of time without damage or overheating the engine. A”250 watt continuous” motor, theoretically, could run indefinitely at 250 watts without overheating, but any more electricity would make it eventually overheat. If the engine is really a 250 watt motor by definition, then conducting this engine at 251 volt will eventually cause it overheat. Why do manufactures offer distinct”power ratings“?
This happens for a number of reasons. A frequent cause is to skirt importation laws. Many European nations restrict imports to electric bicycles with a engine rated at 250 watts or less. 250 watts is not really much electricity by ebike criteria. Professional cyclists may put more than 400 watts on leg electricity alone. This is quite common in the industry. As we saw, a 15 amp controller would mean the actual peak power supplied to the engine is nearer to 540 watts along with a 20 amp controller would be over 700 watts. So in order to clean their electric bicycles for import to as many nations as possible, many ebike manufacturers rate the components in their ebikes much lower than what they are actually reality.
MEET “250 WATT” MOTORS FOR ELECTRIC BIKES HOW CAN YOU BEST USE POWER RATINGS?
A fantastic example are so-called”250 watt electric bicycle conversion kits”. They frequently come with all of the parts except the battery, a fairly standard motor rated by the vendor as”250″ watts, and a pretty good price of about $250 including shipping. But when we look at the specificationswe see that the 36V controller has a peak current limit of 15A. Virtually every retail electric bicycle and ebike conversion kit is listed at a specific power level, such as a”500 watt electrical mountain bike” or a”250 watt ebike conversion kit”, yet often this power rating is misleading or plain incorrect. The challenge is that manufacturers do not use the same criteria to name their engines, and consumers often don’t know the differences. As you may see, calculating the peak power of an ebike is simple.
You just multiply the voltage of the battery from the maximum present the ebike can handle. The current is determined by the control of the ebike, and is somewhere between 15-30 amps. An ebike with a 48V battery and a 20 amp peak controller will be effective at a minimal 960 watts of instantaneous power. Let’s start with a few definitions and a bit of a physics lesson. A”watt” is a unit of electricity, named for Scottish Engineer James Watt. The problem here isn’t the morality of underrating ebike specifications (this is one of the few times you generally get greater than you cover ), it is that this often confuses customers and makes comparing different motors much more difficult. Additionally, this is an interesting illustration of how ridiculous lots of electrical bicycle laws are.
Limiting the wattage of ebike motors does not automatically limit how powerful they can be. Though a motor is indicated as 250 watts (and even though it may really be a true 250 watt motor), anyone could connect it to a 48V battery and operate 20 amps through the motor to reach 1,000 watts of power.
Of course, this may eventually hurt or destroy the engine, but it still demonstrates how it’s completely possible from a practical standpoint. These examples should reinforce the take-home message here: if you’re looking in an electric bicycle or ebike conversion kit, always compute peak watts in mind (volts x amps) to do a reasonable comparison of the actual energy you can expect from any bike setup. This way you’ll know what sort of power level you’ll really experience when you’re ready to spin the throttle.