first; its easier to get more efficency out of a smaller motor [not saying a big motor can't be just as efficient] two; with two motors you can parallel/series switch them so for example if you have one big motor that is equal in power to two small motors then at X amp and Y volts they have the same power, but you can switch the two smaller motors and have 2X amps and Y/2 volts for twice the power at low speeds: basicly its like having a low gear. further with the swtiching you can have two optium speeds for efficency one at Z speed and one at Z/2. for me that would 75 mph for the highway and 37.5 for the city.
plus with my setup its easier to intall two smaller motors than one big one on a hardtail SteveS <[EMAIL PROTECTED]> wrote: I get the idea of the two motor system, but how does compare to using a larger single motor? I imagine a single larger motor would be easier to install and control. The larger motor would deal with the low speed torque need, but I wonder about what happens when you get up to speed? Would a larger motor be less efficient? - SteveS dale henderson wrote: > The advantage of a transmission is more power at low speeds while at > the same time reducing the power needed. But once you are up to a > cruising speed the transmission does not any help except for allowing > the motors to operate at high efficiency at more than one speed. The > disadvantages of a transmission are increased drag, or lower overall > efficiency and increased weight. > The advantage of a two motor system is that a second motor is often, > if not always, lighter, smaller, simpler and more efficient than a > transmission. The disadvantage of a two motor system is increased > power requirement. > Here is another way to look at it: if your main concern is high > efficiency at a particular cursing speed [e.g. highway travel] then > longer you travel the less efficient a transmission becomes and > conversely the more efficient a two motor system becomes. A > transmission only increases efficiency during acceleration once you > are at a steady speed the transmission reduces efficiency in terms of > drag and weight. While a two motor system is only less efficient > during acceleration, so if you have little acceleration and a lot of > steady speed then two motor system is overall more efficient. > Here is a very simple model; if it gives good results then a closer > examination would be warranted: take a 25-mile highway trip, well > give a ¼ mile acceleration; more simply a 100-mile trip with 1-mile > acceleration. At any give time the motorcycle needs X power. A > transmission is 5% less efficient than a non-transmission so over 100 > miles it will take 100 miles * .05 = 5 units more power. The two motor > system will take twice the power at acceleration 1 mile * 2 = 2 units > more power. But if you are commuting in stop and go traffic then a > 40-mile commute might have over a 1 of acceleration. So a transmission > is 40 * .05 = 2 units and a two motor system is still 2 units. So if > your steady speed is more 40 times longer than your acceleration then > a two motor system is more efficient. But if your steady speed is less > 40 times more than acceleration then a transmission is more efficient. > A closer study is needed and results will vary based on > rider/bike/weight/route/etc but I think it will be clear that in > short city travel a transmission is more efficient, but in longer > highway travel a two motor system is more efficient. But since an > electric motorcycle has a finite range and cant be filled up at the > pump then it should be built to be the most efficient for the > longest-range option. Hence once you get an electric bike going over > 50 miles on a charge [i.e. lithium] and you have some plans to travel > on the highway then a two motor system is the best choice. Further > with a 100+ mile range, city travel never be a concern, even with the > lower efficiency of the two motor system, but when a long trip on the > highway is needed the two motor system will shine as it will give you > more range than a transmission. > > > harry > > Albuquerque, NM > http://www.austinev.org/evalbum/1179 > http://geocities.com/solarcookingman > > ------------------------------------------------------------------------ > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try > it now. > > > ------------------------------------------------------------------------ > > No virus found in this incoming message. > Checked by AVG. > Version: 7.5.524 / Virus Database: 269.23.8/1415 - Release Date: 5/5/2008 > 6:01 AM > harry Albuquerque, NM http://www.austinev.org/evalbum/1179 http://geocities.com/solarcookingman --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.
