Making an economic electric bike

[μDriver]

yes but in electric traction the engine will work at its nominal power and not maximum in shot burst, which means that the power delivered is divided by 3 therefore the consumption too, in practice we gain even more because an engine at its nominal power has a much better yield. Then there is also the efficiency / capacity of the batteries compared to the current demand and it is the same as for an engine, a 100ah battery on which we draw 500 amps will not last 12 minutes but much less ...
What makes us that your same battery (this is an example compared to your 10 minutes announced) and the same starter on the bike will be at least 40 minutes.

[Former Oceano]

I don't know if this is a good idea a starter.

The electric starter is also designed to operate for short periods. Will it last for such long durations? Will it heat up? How long the brushes last (VAE motors are Brushless)

Then it will have to be clamped in power to meet the maximum 250W (20,5 amperes in 12V).

Then there is the weight of the starter (it is quite heavy and it is quite strong to run a car with a gear engaged ...).

In short, I do not know if it would not be better to find another electric motor. A brushless would be better, but it will impose electronic management.

[geotrouvetout]

Hello,

why not a brushless, a rewind alternator, but the problem is the controller unless using three sensors (hall effect or opto) which allow the switching of phases.

GEO .

[nlc]

Well, I no longer remembered this post.

Some time ago I was interested in electric scooters, I went up to St Brieuc to try one (it's great!), And the guy told me that if he had known, he would rather have taken a VAE (electric assisted bicycle), given the low mileage it had to do.

Suddenly I asked myself the same question and realized that a large part of my journey could be done on a bike path (separate from the road).
Suddenly, I dropped the scooter and here I am on the VAE! I also thought of tinkering with it myself, and then finally I found a compromise, I ordered a ready-made hub motor, mounted in a 28-inch rim. I will just have to replace the front wheel of my bike (brand new from last Saturday ) with this wheel motor. It's cool, I'm going to have a 2WD !!
I also ordered a 36V-14Ah li-ion battery to power the beast.

While waiting to receive everything, I still have to build the controller, which will manage the motor output, and a pedaling sensor and an accelerator at the input.

The pedaling sensor is to respect a minimum regulation: the engine must shut off when you no longer pedal. In theory we must also cut the engine above 25Km / h .... but we will have to explain to me the danger that it represents if we drive at 35Km / h !!! Especially since it is doable by bike without assistance !! Foolish regulations ....
They would do better to enforce the 45Km / h on scooters which stink, which break our eardrums, and which roll at 90Km / h

[gegyx]

35 km / h, like the Solex.
But helmet compulsory.

[nlc]

Anyway, mandatory or not, and whatever the speed, I believe that a helmet is not too much when riding on the public highway

[MichelM]

Hello
The starter was not a good idea for me, it is made just to start the thermal engine therefore operation at high power and torque for less than 10sec (significant heating) the performance is probably relatively bad (often no rolling and big brushes which rub on a large collector) on the other hand what force it is capable of driving a cold diesel engine plus the car if a gear is engaged .... Me I would rather see a motorcycle alternator (with permanent magnet which resists the heat) it is potentially a "brushless" motor or rather in French a synchronous motor, the power is close to the desired 250W. You need a controller to switch the 3 phases from the battery DC, we could use a model controller to which we would add power transistors (MosFet) in parallel (it works well in model: 2 to 7 per ex). And when decelerating it can act as an alternator ....
Brushless models of reduced model arrive at powers of 1500W and more in peak ...
For batteries Lithium Polymers are very light but seem to have a fairly short lifespan 50 to 200 cycles (?) Against about 500 for Nihm and up to 1500 for Ni-Cd but it depends on the parameters of charge discharge temperature . Be careful with the charge of Lithium Polymers, there are some that burn well. Mandatory slow charge, no short circuit, no heat!
Michel

[μDriver]

Thank you for the idea of ​​the alternator, I had already thought of using a bruschless of model making because I have a few (cyclons with rotating cage) but they rotate much too fast. For the controller no problems because I also bidouIlle the fets on the controller this allows to use low-power controllers very cheap and to use it as a command of fets. On the other hand, a mini-scooter brushless motor and its integrated controller does not cost a fortune because I saw $ 34 out of port.
Question: can an automotive alternator be used as it is or does it require rewinding?

[μDriver]

Anyway, mandatory or not, and whatever the speed, I believe that a helmet is not too much when riding on the public highway

yes and no because even pedestrians should have helmets since cars are the main danger.

[MichelM]

Hi µDriver
A priori it is not necessary to rewind them they are provided for the 14V of the battery at the end of the charge.
The more powerful alternators of motorcycle and car are wound at the level of the rotor (central) that allows a regulation of the power by modifying the flow of induction. But the output must be a little less good there are brushes on 2 rings (but smooth) on the other hand we modulate the power more easily by the inductor with weaker currents and it is autonomous with its shaft and its carcass whereas the permanent magnet alternator of motorcycle the rotor is fixed directly on the crankshaft of the heat engine ...
$ 34 is really inexpensive! Where is it ?
We must pay attention to the quality of the magnets, low-end economic ferrite, super powerful Neodymium Iron Boron but from 80 ° C they gradually lose their strength, Samarium Cobalt (rare earths) almost as powerful and resists the heat from a heat engine but very expensive (motorcycle alternator? or competition).
The cheap modelless brushless controllers where can you find them?
Michel