Originally Posted by
Tohot
Hi to all forum members
I´m so sorry but i have soooo many questions
(i´m trying to make a new vehicle (patent) but it will require some hard core info)
1.0)Engine
1.1)Weight - i would like to know the weigh of all motors if someone has found a list OR at least the weighs of motors that would go 20,30,40 [Km/h] with 100[Kg]/220[lb] person
1.2)Can those weight less than 3 Kg?
1.3)Do this motors have breaks and gears or they actually do everything by power direction (slowing,speeding,stopping etc...) ?
1.4)Why are Wattage AND Voltage differences "needed" ?
1.5)Can 250W/48V Engine be better than Higher Wattage but 12V Engine ?
1.6)Would additional gears on Ebike work? Ok lets just say i can change gears for 1x to 2x Speed so if it goes 5 RPM/Sec it should go 10 RPM/Sec (to the wheel) and reach double speed (or lets say a have motor attached to pedals)
2.0)Batteries (searching for low-weigh batteries but not a lot more expensive too)
2.3)do more voltage batteries weigh more than more wattage batteries?
2.2)how much would batteries that can last 2 Hours weight if they allow me to go a) 20[Km/h] , b) 30[Km/h] , c) 40[Km/h]
2.3)Can those weight less than 3 Kg?
2.4)What would be the recharge time for that 2 Hours?
ANY help will be appreciated
1.1 & 1.2 Weight: I haven't seen a list of all commonly-available motors anywhere. For brushless hub motors, they mostly work the same from one to the next unless you are using it in unusual circumstances -- for example, going up very steep hills or going more than 40 kph. It is possible to have a motor that weighs less than 3kg, but there are tradeoffs. I used the Cyclone ebike kit and found it unreliable. The very small hub motors are light but offer lower performance than other systems. (example:
http://www.electricbike.com/mini-hub-motors/ ).
1.3: You will use ordinary bicycle brakes. Some kits offer regenerative braking in addition -- they are more expensive, and have other downsides as well.
1.4: wattage differences: more watts means your components need to be able to take the power. All of the controller's parts are built to handle specific conditions in terms of maximum volts, amps, and temperature. many hub motors are run at less than their maximum power, so a hub motor sold with a 250-watt kit might be able to handle 1500 watts (it might not). You need a battery that can handle the amount of power you are using. (in terms of amps and in terms of amp hours). Voltage difference matters for a couple reasons. High voltage means that you can put more power through a wire of a particular size. This is why it has become "standard" to run most e-bikes at 36 or 48 volts. The exact same motor can be usually be used at 36 or 48 volts-- it will run faster at 48 volts, whereas 36 volts will give better energy-efficiency, at least in some circumstances.
1.5: There are some really technical reasons why you would want to go with 12 volts or 200 volts or whatever, if you are experienced at building your own systems. If you are not, you shouldn't be concerned with voltage. # of watts (power) does matter -- lots of watts are required for fastest uphill speeds. For flat-ground speeds just look at the speed the seller says the system is capable of.
1.6: Yes -- additional gears on an ebike can work. I recommend you do not use a multi speed e-bike system unless you are interested in going faster than 40kph or going up really steep hills.
2.0: if you want cheap batteries use Lead Acid. If you want reasonably affordable lightweight batteries use LiFePO4.
2.1:voltage does not determine the weight. wattage also does not determine the weight. for a particular chemistry (such as LiFePO4), energy capacity (which is the same as watt hours... which is the same as [amp-hours times volts]) will determine the weight.
2.2:we need to make more assumptions to answer that question. let's say you're on nearly flat ground, not pedaling, on a bike with wide tires and wide handlebars, going for 2 hours, rarely stopping, and your battery is LiFePO4. Based on
http://www.kreuzotter.de/english/espeed.htm you probably need:
20kph: 400 watt hours, or a 4kg battery (at a minimum)
30kph: 900 watt hours, or a 9kg battery (at a minimum)
40kph: 1850 watt hours, or a 18.5kg battery (at a minimum)
2.3: see
#2 .2. "li-po" batteries cost more but give more energy per kilogram, so less than 3kg is possible in your 20kph scenario.
2.4: if you use a typical battery and a typical charger, you should expect a charge time of 4 to 5 hours. If you are really concerned about fast charge time, better numbers are possible.