Hi, in this page i try to convert a regular bike into an electric and solar bike.
Almost all materials have been purchased on eBay, you can also find these materials in a common dynamic model shop.
I used 2 10Ah Li-Po 11,1V Battery in parallel, the benefits of using low voltages are less equalization and problems with batteries, the disadvantages are higher currents, I wanted to exaggerate but also a 7.2V would work too.
As engine, after a couple of small aircraft engines, burned, at high KV, KV means revolutions/(minute x Volt), I tried a brushless with the lowest KV and much more power torque, mine is from about 270KV and even now it is not burned, if you live in city, I recommend you even less KV, because the critical point where it absorbs so much current is at the start and in the city is a situation that always happen.
In my case the engine almost reaches 3500rpm/min with fully charged batteries, a model watt meter (watt'up meter) indicates that motor can absorb 88A as peak power, i also reached 830W, but you have to count that the instrument, the welds and the cables have a certain resistance to the passage of current as well as the speed controller (ESC), first 80A that dissipated as a toaster (about 10W), now replaced with a more efficient 200A .
The motor was directly coupled with the rear wheel for less loss (direct drive), by means of a welded iron holder which is tightened by screws, there are other fixing methods also it depends on the bike (for example by 3d printing a plastic piece), in my case to release it from the wheel just unscrew two bolts and slide it along a broad guide and tighten it to a new position, with the welds helped me my father, keep in mind that after a while time everything will be completely rusted, plastic ties have also a discreet fixing.
As a controller for the motor which is a brushless three-phase I used a ESC for brushless three-phase firstly of 80A and after 200A, except that you have to send him pulsed signals with the standard servo, so i used a servo tester for not to mount a transmitter and receiver on the bike, from which I unsoldered and replaced the potentiometer with a linear one, more comfortable, and then i implement an automatic " pilot key " ( a simple switch that bypss the potentiometer ) .
As my cheap controller does not have the BEC that output 5V to supply the electronics and controller, I used a 7805 which lowers 12V (which then also coming to 9V) to 5V, you can also think about using 4 batteries of 1.2V each in series as the models do, maybe charged by solar panels, in my case the consumption for this solution is of a few mA, to improve the engine friction with the wheel which is made of iron-rubber, cutting the air chamber holes rings, by a few centimeters to turn friction into rubber-rubber, also to decrease the ratio 8:1 as much as possible and also to limit the corrosion of motor (Fe), except that the rings after a while they tear and broke, and not all the air chambers are extensible. The engine at the end of a slope is so hot that you can't touch it, especially with the rubbers around, even with the rotating case directly on the tire works equally well (if not raining) and cools better.
Then I added 2 x 6V solar panels in series to charge the batteries though a diode (1n4007).
I also use a normal lipo charger for recharge the batteries.
I also added lights and i can't find a tiny 200A switch, so i connect the 2 wires handly.
Consumption in money, without making too many calculations, if a round trip of about 10km total, equivalent to 100Wh (every day) = 0,1kWh then with 1kWh you can make about 10 trips (10 days) and 1kWh costs about 0.2 Euro (in Italy), tripled it and get the cost per month which is about 0.6 Euros, even bigger the battery, the power consumption would remain more or less the same, but if you weigh a lot and drive like motorbike GP style and make the drift and burnout at traffic lights then increases.
With bigger and slim wheels you can do much more kilometers.
I hope you like it.