Q128c question

[Axeman99]

Hi,

This is my first post, and if these questions seem stupid I'm sorry!

I am going to buy the q128c rear hub motor but I think the 201 rpm version is too slow and the 328 rpm version is too fast. I have had contact with a salesperson at BMSb, who says that it's not possible to change the rpm by overvolting the engine. I have read on this forum about people overvolting their motors.

My questions are:
Is it possible to overvolt the 201rpm 36V motor to 48V, or maybe undervolt the 328rpm 48V motor to 36V, and what would the difference between these alternatives be?

BMSb did not have replacement gears for this motor, do you think there will be a problem getting gears for the motor when they eventually wear out?

The motor is going to be used with PAS on my homebuilt recumbent tadpole trike.

 

[motomech]

The Q128C is also offered in a 48V version.
A 328 @ 48V is about 260rpm @ 36V, in effect, a mid-speed motor.
The Q128 was discussed at length in this recent thread;

https://endless-sphere.com/forums/viewtopic.php?f=3&t=76519&p=1157945&hilit=+q128#p1157945

 

[toine-s]

Last weekend I finished my bike using
a 36V Q128C 201rpm
a 48V 20 amp SO9 controller with battery (panasonic)
I chose 201rpm for climbing capabilities and 48 v on 36v motor for some speed.

Today I've take a GPS and did a short trip.
As we have no mountains here in the netherlands i rode up a bridge.

These are my observations..
max speed 37.6 kph. is also as fast as I can peddle on 48x14. Plenty fast enough for me. It is hard to be below 30kph, the motor is pulls strongly.
going up the ramp I noticed almost nothing. The torque of the motor easily drags the bike and my up the bridge ramp.

Good about the BSM kit: all looks nice and tidy with waterproof connectors and integrated controller. I did shorten the cables by cuttomg soldering them inside the controller to be an exact fit.
Besides some installation issues related to bike geometry, which could easily be fixed i have 2 issues
1) a resistor in the controller gets very hot, resulting in a molten spot on the controller housing
2) the pas sensor does not work.

I'm abou to order a second kit for my wife but BMS has to solve these 2 problems first.
I hope thet reading this

 

[Axeman99]

Thank you for the information!

That speed would be more than enough for me, since I will be using it in a trike.

I will be buying the -09 battery without the controller because I will buy another battery later to increase range, and I think it would be difficult to connect more than one battery to the internal controller.
I was thinking of buying the S12S controller, but I notised that it didn´t have an output for lights, so I´m leaning towards the S12SH controller. Does anyone know if there is a more suitable controller with
output for bicycle lights?

 

[motomech]

The S12SH might be a little much for the 500W Q128C.
The light output on these controllers is just switched pack Voltage and if the light draws any kind of serious current, I would prefer dedicated wires/switch.