Bafang front hub 250watt motor more speed

[Christoflombart]

Dear members,

I wanna build my e bike like a speed pedelec for more speed on canalroads (no traffic) to commute to work.
I have a e bike with a 250 watt bafang swx02 250watt (12)front hub motor(disc brake) it has a lishui 15a controller on it and goes 32km/h.
I have allready tried the 20a controller and lcd3 display (from my diy cargo bike)on it to try if the bafang motor goes faster .
It still stops at 32km/h and at 30km/h the wattage starts to drop to 100 watt. So I thinks it's limited thru the motor speed sensor.

How can I put some more speed in the bafang motor and keep the controller pushing more than 100 watt above 32km/h

If this bafang motor is capable of hitting 45km/h with a 36v and 20a cntroller i will buy a
KT bluetooth controller of 36v with 20a
And Bluetooth dongle for phone app display .

Can anybody please help me with the speed limitation?

. Bike video

 

[Nealh]

Any motor speed is governed by the motor winding (rpm), once this is reached the motor reaches a saturation point where as you have seen the power backs offs having reached the optimum speed, also known as Back EMF.
The only way to increase the speed and to prevent BEMF is to raise the voltage, current has little to do with speed.
What size wheel are yo using ?

 

[Christoflombart]

Wheel size is 28"
Today i have reached 34km/h with full battery.
How much will I gain with a 48v battery and controller?

 

[Nealh]

34 km/h / 21 mph suggests the motor is 260 or 270 rpm, at 13s/ 48v one should manage close to 45 km/h /28mph and see the motor rpm increase to approx 346rpm. 14s/52v would be more comfortable. For a 700c/28" wheel one needs approx. 12.2rpm per 1 mph.
How much current the swx02 will take I don't know but one could try s09s 22a/25a model and dial back the current to start with, you should be safe at 18a. Your only real worry is stripping the planetary gears on the clutch due to heat/current supplied.
So spares may be handy just in case.

A few years ago (4 or 5 ) a guy on pedelec.de put 35a & 60v through a swxk with some oil cooling without damage, this was on a hot rodded tadpole.

 

[Nealh]

Just seen the pic, motor is code 12 so is 260rpm.

10 -15 mls of ferro would keep things cooler if you opt for higher current.

 

[Christoflombart]

So if I buy this controller from kunteng and Bluetooth of 48v i can drive 45km/h with peddeling or without?


36 V of 48 V Universele (ondersteuning zowel spanning)
Nominale Spanning: DC36V/48 V
Nominale Stroom: 12A
Max Stroom: 25±1A
Laag Voltage Bescherming: DC30/40±0. 5 V
Controller (meer stabiele, hoge efficiency, lage stroomverbruik, lange levensduur)
Ondersteuning LED Bedieningspaneel of LCD Bedieningspaneel of zonder Bedieningspaneel (Universal)
Ondersteuning Elektrische Lock Functie
Ondersteuning 36 V of 48 V

I also gonna build a new 48v battery for it to fit in the bike

€ 88,82 5%OFF | Dorado Id-Max Reention Batterij Doos 36V 48V 52V Lithium Batterij Elektrische Fiets Accu case Voor 80 Pcs 18650 Li-Ion Cel

 

[Nealh]

Both pedal & throttle.

 

[Christoflombart]

Thanks for the help nealh.
Do you have a YouTube channel of you're build?

 

[Nealh]

No don't do viral stuff like that.

 

[PC2017]

No don't do viral stuff like that.

I'd like to think you would go viral if you ever posted a build vid Neal

 

[Chabsy]

Just seen the pic, motor is code 12 so is 260rpm.

10 -15 mls of ferro would keep things cooler if you opt for higher current.

Hi

Could you share some info on this ferro thing please What how and where exactly? Im planning to build exactly the same setup only with a rear hub .
Thank you

 

[PC2017]

I think its a coolant - I run a circa 230 rmp motor(black) "rated" for 36v at 48v max 14a controller and had no over heating issues on the motor, my overheating issues happened in the summer (18+ degs C) with my controller, tbf I could only get a 14a max dual voltage sine-wave(as I do still have 2x 36v batteries for the same system) in black metal and this black absorbed heat and cut out my system frequently, although we didn't have an extremely hot summer last year temps still got high but after unibond tape, some CPU thermal paste and a few ebay gold heatsinks, it worked fine all summer. Thinking irrationally could I cover my motor with gold heatsinks Might look naf.

I would imagine anything over 20a would heat up quickly @48v - remember 48v is nominal and they start at 54v(ish) I get 22 mph and I feel for off road this is enough, on road I limit to 15.5 of course.

 

[Nealh]

For ferro fluid ideas one has to look or ask on the endless sphere forum.
Luna's take on it.
Luna Ferrofluid (statorade) Hub Motor Coolant 10mL - Luna Cycle

 

[Chabsy]

For ferro fluid ideas one has to look or ask on the endless sphere forum.
Luna's take on it.
Luna Ferrofluid (statorade) Hub Motor Coolant 10mL - Luna Cycle

Probably im wrong but the Bafang rear hub is geared i think and Luna says this about geared hubs : Support note: not intended mid drive motors or geared hub motors, direct drive hubmotors only (no gear reduction inside)

What should i do in this case ?

thank you

 

[Chabsy]

Probably im wrong but the Bafang rear hub is geared i think and Luna says this about geared hubs : Support note: not intended mid drive motors or geared hub motors, direct drive hubmotors only (no gear reduction inside)

What should i do in this case ?

thank you

It wont overheat you dummy ! Read above !

 

[Chabsy]

It wont overheat you dummy ! Read above !

Ah ok thanks !
Im absolutly new to ebikes and trying to gain some knowledge here and there. I would like to ask a couple of questions just to see clearly before i would buy the wrong parts.
1.: 250w bafang rear hub check. If im buying a 36v/48v controller and im buying a 36v battery and separately a 48v battery my bike will go faster if i insert the 48v battery and slower/normal speed if i insert the 36v battery in the slot? Should i look out for the Amps ? Like 36v 20a and a 48v 15a so they would have a similar Wh or it doesnt matter.
2.: on the kt lcd3 i will be able to set the top speed by adjusting the maximum of the Amps?
3.: is there a different rear hub/ controller / that worth considering . Im Low Budgetman .

thank you
Thank you
Thank You

 

[PC2017]

There's plenty of info on this forum, try using the search.