Merlin Kendal MTB 250W rear hub driven

[Rissien]

Hi all,

I have bought a shop display Merlin Kendal which developed a random power loss fault after only 1 week.
The great guys at Merlin replaced with a brand new one for me = 1 happy chappy.
I love the bike and it is awesome climbing hills..... it just seems to run out of steam at about 16 mph.
My friend said it may be the RPM of the 8fun 250W motor. Would replacing the motor for a higher rpm increase the flat speed of the bike? I have changed the speed cut out setting in the LCD from 25kph to 35kph but no difference.

Any help gratefully received
bike details at http://www.merlincycles.com/merlin-kendal-electric-mtb-bike-85956.html

Many thanks

Paul

 

[Nealh]

There should be a code on the hub to determine its winding /rpm, it should be a number in the range 8 - 16. The speed setting is probably programmed in the controllers pcb.

 

[Rissien]

Many thanks for the reply Nealh, with my current setup could I replace the rear wheel/motor with a 350 or 500w one or would I have to replace the controller and lcd computer?

Thanks

Paul

 

[Nealh]

You may be able to derestrict the speed by playing with the parameters in the LCD. Just reread your first post you have tried that.

Many thanks for the reply Nealh, with my current setup could I replace the rear wheel/motor with a 350 or 500w one or would I have to replace the controller and lcd computer?

Thanks

Paul

The above depends on your battery ah and the controller amps.
15-18a for 250w, 18-22a for 350w and upto 25a for 500w. Lcd should be fine.
However you haven't told us the motor code to cipher the winding.

 

[Rissien]

Hi Nealh, just took a few pics of what I can, also the number on the side of the motor is BFY1305H15430

 

[Nealh]

Your bikes leccy specs are a bit weedy the 8fun motor is ok probably wound for 201rpm as Merlin say its high torque and you say it climbs well. The Controller is 12a max the motor will take 15 if not more, the battery will take 15a but range will suffer a little. You could try another controller with a bit more amps this will give the hub more power and might increase speed 1 - 2 mph, if you are handy with a soldering iron you could try a shunt mod to the controller and up the amps a bit. A more powerful hub is a no go with that controller and the battery is a bit small ah wise. Also chain wheel and hub freewheel gearing if upped may give a few more mph when peddling.
Alternatively you could try over volting with a 48v battery and a 18-20a controller this would increase mph x 25% and increase torque but everything comes at a price as in £££'s

 

[KirstinS]

That motor will run quite happily at 48v 14a unless you have lots of hills. I ran one for nearly a year without issue on my flat commute. Then I tried tob climb Brighton steepest hill and the heat generated in the motor melted the plastic gearing cogs

I'm not sure you can take the motor to 18a or more and 48v. Think you might just up with trashed motor - that's too many watts for the motor windings I would suggest

 

[KirstinS]

A ku65 controller from bms battery will give more torque and 2/3 mph more. And won't kill the motor

That's the cheapest solution I'd suggest

 

[Rissien]

Many Many thanks or the replies guys... I am thinking I should of gone done the 'build my own e bike' and bought the bits separate. Rather than pay £650 for the stock off the shelf one ( ex display price ).

Would the KU65 controller be an easy swap as my controller is built into the Bottle battery holder?

 

[Nealh]

KU 65 & KU 63 dims are 31mm x 52mm x 82mm, BMSB say its only compatible with LED810. KU63 is identical so I assume it is ok for LCD as BMSB don't say otherwise.

 

[KirstinS]

KU 65 & KU 63 dims are 31mm x 52mm x 82mm, BMSB say its only compatible with LED810. KU63 is identical so I assume it is ok for LCD as BMSB don't say otherwise.

Yes, sorry. You also the need the led panel. They come together as I recall?

 

[Rissien]

thanks guys...... if I got the BMSB controller KU63 for LED display... would it be easy to swap with my controller...only reason I ask is that if I have to start re-wiring I think it will invalidate my warrenty....it may be worth leaving it until my 12month warrenty has expired...if it is possible to 'plug and play' I think I will be ok?