Electric Bikes

[1198]

I think Tesla, Toyota and all the other successful manufacturers need to employ this ‘wizened old electrician’ immediately. He obviously understands the problems of electric vehicles much better than their multi million pound development engineering schemes ever will...






......and they’ll have (unnecessary) gearboxes too!

[TravisBickle]

[st3v3]

[Robby]

If you have a small, revvy bike then you need all 6 gears to make use of it. There is little torque low down, and the torque spread is narrow. Same for 2 strokes, that you have to keep on the boil.

Big-engined cruisers with a lot of torque can get away with less gears, and a lot less gear changing. Stick in 4th and ride.

Electric bikes have something like 5 times the torque of a big-engined cruiser. So they are fine in top gear.

Whilst there may be some small efficiency improvements from using a gearbox in some cases, they aren't enough to justify the cost, weight and friction penalties. That's space and weight that could be used for more batteries.

[Coby]

Possibly true, but more batteries weigh a lot as well.

Smaller motor, less batteries and a gearbox might be more fun.

[Kawasaki Jimbo]

But range? You continue to suppose that manufacturers have deliberately chosen to use sub-optimal designs because they haven't thought it through like you have. Seems unlikely doesn't it?

[Coby]

They're Americans!

[Easy-X]

[Easy-X]

Just trying to drag this thread back to some semblance of normality I did wonder how much of difference it would make if you took the lightest race bike you could find, add on the lightest motor (probably 250 to 350W wheel hub motor) and then run a minimal battery.

For a 36V battery you'd have at least 10 cells in series. However the current output wouldn't be enough to supply a motor's needs so it's usual to run 3 or 4 parallel banks of cells. If one were to use high output cells (decent branded Sony, Samsung, etc.) you might get away with a 10S2P pack (2 parallel banks of 10.)

If a typical cell weights 50g that's half a kilo saved! Woohoo!!!

Yeah, probably better to eat less pies
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[dynax]

Just mount a bloody generator to power the motor, no law to say you can't use an engine to supply electric there is no direct drive between the engine and bike, and 8+ hours of running time off a tank
____________________
Mike.
Bikes: Xena, Bridget,Florence
https://www.youtube.com/channel/UCmihUc0xXxYbR4_0l-F1FzA/videos?view_as=subscriber

[Coby]

The Zero (I think that's the name) still has a crap distance coverage per charge (maybe 110 miles from memory), unless you 'double' the size of the battery bank!

That's got to add a lot of weight (and cost I believe).

[Easy-X]

[Campbell SOUP]

[Easy-X]

[Coby]

So Campball;

Are you claiming that there is no longer any need for 'C' or 'D' type circuit breakers?

[Coby]

Perhaps not.


Ok, 'E' vehicles are still left with two basic problems then:

(i) - The initiation and acceleration of a rotating electric motor.
(ii) - The initiation and acceleration of the rotating drive wheel(s).

Both of the above will inevitably require more energy than for their rotation, once each is up to its' required rpm!

[Campbell SOUP]

[Coby]

Ok, here's fun:

Can you come up with some prospective current consumption figures for six different gear ratios @ six increasing voltages?


By the way:
You didn't mention whether or not 'C' & 'D' Type circuit breakers are now redundant!
You are starting the motor under load remember.

"Efficiency comes from 'more' current being used than is required"? It's current usage that's killing the batteries!

[Campbell SOUP]

[Pete.]

Brushless DC motors are nothing new. I was winding prototypes in the 1980's.
Inverter drives aren't new either, and if you think they are only available for small motors then you're sadly mis-informed.

Star-delta is old hat. EV motors are DC and powered by drives with very complex algorithms.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[1198]

[Easy-X]

2-strokes cars... keep thinking of the fact the transmissions needed a freewheel or was that just the Trabant?
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Campbell SOUP]

[Pete.]