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

[snillet1992]

Hi guys!

Just got a 250w fatbike that I feel is to slow. Is there any way to increase the top speed without buying a stronger motor?
I've done a ton of research and found noting that works on the bike i own. Any ideas?

I got the Volta VB2: https://volta.com.tr/product-category/electric-bicycle/vb2-en/?liste=vb2-en&nam=154&desc=on

Most important specs:
Motor: Rear hub 250W
Battery: 48v
Controller: DC48V
Display: AK47

Just tell me if you wanna see pictures of controller, or cables or anything else.

My general feeling is that the 250w motor is too weak to bring the bike to a higher speed than 25 kph.

I cannot find any speed limiter wires on the controller.

I already set the display settings to 41 kph, but doesn't seem to make any notisable diffrence.

I don't want to install a throttle.

Seems like the speed is measured internally in the motor because i can't find a magnet for a speed sensor anywhere. Could that be right?

What can I do to make it go faster for as small amount of money as possible?

Thanks!

 

[Nealh]

Speed is likely hard set in the programming.

 

[snillet1992]

Speed is likely hard set in the programming.

Yeah, but do you think that the motor is what limits me or can a 250w motor be able to travel faster on a 20" fatbike like this? I mean i did set the display to 41 kph which was the maximum speed in this display.

 

[Nealh]

As I said programming may be holding the speed back.
If it isn't programming then one would need to know th motor rpm winding rpm to know if it is the hub motor.
I have displays that go to 70km/h but doesn't mean I can.

 

[snillet1992]

As I said programming may be holding the speed back.
If it isn't programming then one would need to know th motor rpm winding rpm to know if it is the hub motor.
I have displays that go to 70km/h but doesn't mean I can.

Ok thanks. Then I guess it could be worth trying to change the controller?

 

[Nealh]

One can't just change the controller as a paired matching display is also needed.
As I mentioned one needs to also know the motor rpm winding, the motor won't electrically run faster then it's terminal load speed unless higher voltage is applied.

 

[snillet1992]

One can't just change the controller as a paired matching display is also needed.
As I mentioned one needs to also know the motor rpm winding, the motor won't electrically run faster then it's terminal load speed unless higher voltage is applied.

Yes, ofc I would change the display too.
I just watched this video that explains how you find hidden functions on your controller:

Watch from 8:55

Maybe I can solder a button on the controller to use the 120% speed feature?

How do you know what motor rpm winding you have?

 

[flecc]

Seconding Neal's comments, it's rare for a hub motor to have a wind that can exceed 16 mph in a 20" wheel. I only recall one offhand, an A2B 20" wheel model that had a wind for 20 mph.

With your's already on 48 volts it's unlikely you'll achieve more with that motor. As a general rule with wheel hub motors it's always best to buy with the speed you want in the first instance. Trying to increase the speed later is invariably complicated and expensive.
.

 

[snillet1992]

Seconding Neal's comments, it's rare for a hub motor to have a wind that can exceed 16 mph in a 20" wheel. I only recall one offhand, an A2B 20" wheel model that had a wind for 20 mph.

With your's already on 48 volts it's unlikely you'll achieve more with that motor. As a general rule with wheel hub motors it's always best to buy with the speed you want in the first instance. Trying to increase the speed later is invariably complicated and expensive.
.

Yes, I can see that now. Would just be nice to be able to have a 250w motor that can run that fast. But I understand that it's complicated, that's why i came to this forum. Seems like there is alot of people here that know what they're talking about

 

[Nealh]

One expects your hub is wound for 260/270rpm which would equate to a max 25km/h speed for a 20" wheel, If the same hub motor was placed into a 26" wheel then one would see 28 km/h or up to 31 km/h in a 26" wheel.

 

[flecc]

Yes, I can see that now. Would just be nice to be able to have a 250w motor that can run that fast. But I understand that it's complicated, that's why i came to this forum. Seems like there is alot of people here that know what they're talking about

Theoretically you can achieve the big speed increase you want by changing to a 72 volt battery. BUT and it's big but, that voltage is illegal, you'd have to buy a controller that could handle 72 volts and replace your battery with a 72 volt one.

So costing a huge amount, the bigger battery having to go on the carrier. making the bike tail and top heavy, and a lot to lose if the law confiscated and destroyed it, as they are entitled to with the laws on assist speed, power and voltage all broken.
.

 

[flecc]

One expects your hub is wound for 260/270rpm which would equate to a max 25km/h speed for a 20" wheel, If the same hub motor was placed into a 26" wheel then one would see 28 km/h or up to 31 km/h in a 26" wheel.

Reminds me of the Ezee Quando and Torq, both using the identical electrical setup.

With no controller limiting, the 20" wheel Quando's assist speed ranged from 16mph down to 14 mph as the battery discharged.

The Torq with the motor in a 27" wheel (700c) would spin to 26 mph with the motor wheel lifted off the ground, but could only assist to 22 mph at best in calm level ground conditions.
.

 

[Nealh]

It's the same old story someone wants a legal pedelec then want to make it illegal by increasing the speed.
Yesterday I was able to reach 33km/h with my 250w hub motor but that was using my own power only, my cut off speed is set for 22km/h so I get a bit more range from the battery.

 

[WheezyRider]

Theoretically you can achieve the big speed increase you want by changing to a 72 volt battery. BUT and it's big but, that voltage is illegal, you'd have to buy a controller that could handle 72 volts and replace your battery with a 72 volt one.

So costing a huge amount, the bigger battery having to go on the carrier. making the bike tail and top heavy, and a lot to lose if the law confiscated and destroyed it, as they are entitled to with the laws on assist speed, power and voltage all broken.
.

Flecc, can you clarify the laws on the voltage you are allowed to use? I thought it just had to be stated on the battery, but I have not seen a limit anywhere, or for example whether it's breaking the law to run a 36V battery at 48V.

 

[flecc]

Flecc, can you clarify the laws on the voltage you are allowed to use? I thought it just had to be stated on the battery, but I have not seen a limit anywhere, or for example whether it's breaking the law to run a 36V battery at 48V.

I dont remember the exact figure in the regulations, but it's a design regulation. Its over 50 volts, but 72 volts isn't permitted on these light applications. It's an EU regulation but we retain all of those via the Great Repeal Bill which wrote them into UK law.

48 volts or it's peak voltage when fully charged isn't any problem.
.

 

[StuartsProjects]

Some comments on battery voltages here;

https://www.pedelecs.co.uk/forum/threads/legality-of-battery-voltage.38104/

 

[WheezyRider]

48V is a bit of a difficult one for lithium batteries, in terms of getting a nominal voltage of 48.

If the voltage limit is based on the EU Low Voltage Directive, it seems the limit for AC is 50V, but 75V for DC:

Low Voltage Directive (LVD)

About the directive, implementation and guidance, standardisation, and contact points.

ec.europa.eu

Have I missed something?

 

[WheezyRider]

Ok, have found this pdf of the BS EN15194-2017 regs.

It does seem to mention max rated voltage of 48V. Then the charger is covered by the LVD regs if it is over about 42V.

 

[flecc]

If the voltage limit is based on the EU Low Voltage Directive, it seems the limit for AC is 50V, but 75V for DC:

But of course a 72 volt lithium battery fully charged will be at almost 82 volts, way over the 75 volt DC limit.
.

 

[WheezyRider]

But of course a 72 volt lithium battery fully charged will be at almost 82 volts, way over the 75 volt DC limit.
.

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?