Topic: Voltage question

[Benniz]

I am wondering if anyone can help advise me with the following question

I have decided to instead of using the standard belt drive motor system of my c5 to opt for a more modern/lighter brushless hub motor fixed in the middle of the wheel. Because of the c5 chassis I feel that fitting it on the front is the easiest option other than redesigning the rear axle.

After much asking I have successfully found someone who will make me a 250w 12" front wheel

My main question I guess is about voltage... I can choose from 12v up to 48v, I have been told various things about the importance of voltage, I have been told that more volts means more torque/power and also that the smaller the volts the more amps and bigger the wires have to be and the the lower the volts the hotter the motor gets.

I want enough power to the motor as a normal good e bike so unassisted it will easy do around 10mph uphill and 15-20mph on straights with a nice ommph to go with it

I also want to obtain the longest distance on the battery's possible without going over the 40kg legal UK weight and understand the lower the voltage the higher the amp hours (I will be using lifepo4's not lead acids).

Also I am thinking of maybe adding some small solar panels so keeping the voltage down would be useful for this also.

With all those factors of what I want from my c5 what do people think I should go for. I am thinking of going for a 24v motor at this time but would like to hear any suggestions to go 12v instead or higher.

Another small question is that if I am to do this, plus make it fully enclosed similar to rays ubmobile as long as it is still 250w and under 40kg this will still be road legal? does it matter if you have customised it yourself? I know that velomobles are fine so I hope making/customising a c5 yourself is still ok

Kind regards Ben

[Karl]

..this is from the Battery Vehicle Society website ;

Not all electric bikes are the same and if you’ve never tried an electric bike, here are a few pointers to help you identify which is the right bike for you.

Know the law

The law defines an electrical pedal assisted cycle (EAPC) as a pedal cycle with a small electric motor to assist the rider.

Maximum powered speed of the cycle is 15mph and the maximum motor power is 200w continuous output (250w for a tricycle).

The maximum weight for the electric bicycle is 40kg (60kg for a tricycle) and this weight includes batteries.

In addition, an electric bicycle must conform to normal bicycle construction and use regulations.

Electric bicycles are regarded in law as a bicycle and not a motor vehicle. As such, any electric bicycle conforming to the above definition can be used without insurance, tax, MoT certificate or safety helmet. The only caveat is the rider must be 14 years old or over.

When you are buying an electric bike – especially if you are buying across the Internet – make sure the electric bicycle you are buying conforms to these regulations. A surprisingly large number of them do not and this could have serious repercussions for the owner: buy an electric bicycle that does not conform to the EAPC legislation, and you can be prosecuted for driving an un-roadworthy motor vehicle without tax, insurance, and MoT. Have an accident in an electric bicycle that does not conform to EAPC legislation and you face prosecution with a likely prison sentence at the end of it.

Power, power and more power

Electric bikes aren’t exactly the most powerful vehicles on the planet, but there is huge variance between different bikes available. By law, power output on an electric bike is limited to 200w, although voltage isn’t specified.

As a rough rule of thumb, higher voltages equate to more torque and better performance. That isn’t always the case though: electric motor performance varies considerably from manufacturer to manufacturer and some of the better designed bikes perform better on a 24v system than the cheaper bikes do with 36v electrics.

Most electric bikes have hub motors built into either the front or rear wheel. In general terms, rear wheel motors tend to be better, both for bike balance and also for low speed manoeuvring. In most instances, the hub motors themselves are single geared, so even if you can change gears on the bike itself, the gear change will only affect your pedalling, not the electric motor.

There are one or two exceptions to this rule, and the benefit of having a geared motor is improved hill climbing abilities. However, the difference tends to be slight, and for most owners this benefit is outweighed by the reduced ease of use.

[Benniz]

So because the c5 is classed as a recumbent tricycle does that mean I can go to 60kg max?

[Umpa]

yes 60Kg but your dream of powered 20mph is no good m8. Also it has to be able to be pedaled.

[Benniz]

Thats great umpa, what I meant by 20mph is for downhill and assisted pedalling which I achieve on my bike , My c5 will still have pedals of course so should all be above board

[Umpa]

Sounds like a plan let us know how you get on.

[fezza_rs]

You could make it so its just a motor that assists your pedaling if you put gears on the pedal drive system you can have a top speed that far exceeds what the motor can do alone. Just search sturmey archer c5 on hear on on google and you will see just how simple it is to do!