Easiest way to increase top speed from 25kph to 35kph on 250w fatbike

[flecc]

Well, I was mainly thinking about the 48V nominal for lithium cells, so you'd be at 46.8 with 13 cells, but one more cell would push you over the limit.

Is this the get out clause?

"...voltage up to and including 48 V d.c. or integrated battery charger with a nominal 230 V a.c. input."

So if the charger is integrated into the battery, could 72V be ok?

It depends what that means. It could mean only when running connected to the mains, as some TV sets and laptops are, battery voltage supplied but run while connected to the mains.

Others in here have been adamant that 72 volts is not acceptable. Anyway, who would want to cycle a 72 volt battery around. Not me for sure.
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[WheezyRider]

It depends what that means. It could mean only when running connected to the mains, as some TV sets and laptops are, battery voltage supplied but run while connected to the mains.

Others in here have been adamant that 72 volts is not acceptable. Anyway, who would want to cycle a 72 volt battery around. Not me for sure.
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Not sure if a pedelec with a cable attached would be much use...would need a very long extension cable

A 72V bike need not be dangerous if it is properly implemented. Electric cars run at much higher voltages.

 

[flecc]

A 72V bike need not be dangerous if it is properly implemented. Electric cars run at much higher voltages.

Yes, my Nissan Leaf e-car has a 400 volt 100Ah battery under my seat.

But that is very different from pedelecs in numerous ways. Pedelec batteries are more exposed to damage, removable for charging indoors, easily tampered with and don't have the accepted connector standards and very sophisticated chargers and software that chargers and e-cars have.
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[flecc]

Not sure if a pedelec with a cable attached would be much use...would need a very long extension cable

No problem.

Where I used to live at one time, all the municipal buses were trolleybuses, quiet, very powerful and connected to the mains all the time. The chumps got rid of them in 1969, in favour of diesel buses.

I bet they are kicking themselves now!
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[Chainmale]

No problem.

Where I used to live at one time, all the municipal buses were trolleybuses, quiet, very powerful and connected to the mains all the time. The chumps got rid of them in 1969, in favour of diesel buses.

I bet they are kicking themselves now!
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Would those have been bright blue trolleybuses by any chance

 

[flecc]

Would those have been bright blue trolleybuses by any chance

No, they were yellow with a brown waist lines, run by Bournemouth Corporation. Known locally as the silent service, they ran for some 36 years.

Sad and lacking foresight that so many rushed to get rid of them, from places as far apart as Newcastle, Llanelli, Belfast etc. They're just what we need in these climate crisis days.

 

[Chainmale]

Here in Walsall our trolleybuses lasted until 1970 when the corporation transport dept was absorbed into the newly formed West Midlands Passenger Transport Executive.

 

[flecc]

Here in Walsall our trolleybuses lasted until 1970 when the corporation transport dept was absorbed into the newly formed West Midlands Passenger Transport Executive.

National government policy interference again, in preference to local knowledge. Here in South London, having dug up all the tram lines by the early 1950s, we've got them back again with a new tram system, spanning Merton (Wimbledon) in the West to Beckenham in the East, covering four boroughs.
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[lightning]

Hub drive motors clearly have a rpm limit as mentioned above, with a mid drive motor it's different as you are driving the rear wheel through your gears, so in high gear my friend's de-restricted Cube ebike rips up to 26mph. (where legal of course)

I was interested to see how fast my hub drive Mirider 1 would go, if not restricted. l changed the wheel size from 16" to 14" in the settings, so now when the display says 15.5mph it's actually doing around 17mph according to my GPS speedometer

What l have found is, that unless the battery is fully charged (the first couple of miles of a ride) it won't actually hold an indicated 15.5mph (just turning the cranks slowly to keep it going and not putting in any effort myself) it gets to around 14.9mph indicated (actual speed around 16.5mph)

And if you start to pedal, it still can't seem to assist past an indicated 15mph (actual speed on my GPS 16,5mph)

So l would say, that a 250w hub motor would struggle to drive an ebike much more than 16mph....l imagine due to the design and motor windings, as already explained earlier in this thread.

l guess if you increased the battery voltage things might change, as long as the motor held out.

 

[Nealh]

The oxygen 36v Bafang CST 250w 17a controller kit topped out at 24.5mph.

 

[lightning]

l need to fit one of those then !!

 

[Nealh]

That was 24.5 in 700c wheel size, the motor was already wound for 300 rpm so one likely would have to go to 48v in a smaller wheel size.

 

[lightning]

Ah okay

lf l set the cruise on my bike to an indicated 15.5mph it will only manage it for a short time and then it ends up around 14.5mph

Bearing in mind that's an actual speed of around 16mph

So if l were to de restrict it, unless the wind was behind me l doubt it would go any faster on motor power.

 

[Nealh]

As battery voltage decreases so will motor rpm slightly The hub will have max rpm for the voltage but once the voltage decreases so will the rpm to a degree hence the terminal speed reading drops.

 

[lightning]

That makes sense.

So the motor is designed with the U.K. speed limit in mind by the looks of it.

 

[Nealh]

The motor rpm is chosen for not only UK speed limit but also the EU and likely most other countries where the 25km/h rule is legal.