Help! My next project

[Peter.Bridge]

I was thinking of using a 260 rpm akm-128cst for my gravel bike. I was thinking of running one marked as 201 rpm 36v at 48v but I just thought, could also run one marked as 328 rpm 48v at 36v

@saneagle if I got a 36v 201rpm akm-128cst and ran it at 48v, and set the controller to 18 amps max, would you think that is likely to be ok ?

 

[guerney]

it seems to be a bit lacking in the steep hill department.

If changing settings doesn't work, reduce motor wheel size to 24" for a bit more torque?

 

[Benjahmin]

Well that took some time - doesn't it always? Because I've been using MP tyres for the last 12 years, the glue in the puncture outfit I had had gone solid. Result was a 28 mile round trip to the bike shop to get patches and spare tube. Plus side is that they had some no glue self stick patches, seem to work well.

If changing settings doesn't work, reduce motor wheel size to 24" for a bit more torque?

Might do but it would also mean the cut off operating at a lower actual speed unless I increase the max speed which would defeat the object of trying to build a fully legal bike - aaarghhh !

 

[guerney]

Might do but it would also mean the cut off operating at a lower actual speed unless I increase the max speed which would defeat the object of trying to build a fully legal bike - aaarghhh !

Can't KT controllers calculate speed of a 24" motored wheel?

As an aside, your 36V batteries would power a fully unlocked UART BBS01B (if current limit can be raised to 20A = 720W) converted bike up those hills just fine, gearing permitting. Trouble is, the UART controller's current limit could be locked and all new BBS01B kits for sale appear to be Can Bus, which can't be customised much... but there are UART controllers available to buy which fit BBS01B motors - whether or not they're current limit locked is anyone's guess, unfortunately. Bafang has ruined things for hill climbers.

 

[matthewslack]

The same.

OK, the consistency eliminates some possible causes. Not the throttle, not the PAS, definitely the algorithm, which might respond to settings, although I can't help there.

If this is not normal for a KT setup, perhaps someone with greater experience is able to shed light.

I wonder if the use of the 328rpm motor in a 700c? wheel is affecting the algorithm? It will hit 25km/h way below 328rpm, doesn't often get above half it's intended operating speed, although 36V vs 48V also makes a difference.

 

[Sturmey]

I wonder are you using an older square wave controller rather than the more modern sine wave controller. There has been reports on this forum of difficulties with AKM motors on square wave controllers that were solved by changing to sine wave controllers. e.g.

AKM100

We own three 20" bikes with the Q100H 260 rpm motors from BMS battery, All powered with 20A KT 6-FET controllers (two are sinewave), I built a fourth one this year, using an AKM100 from topbikekit..I pulled out an old BMS Battery P06 17A square wave controller to run it, but it would stall on...

www.pedelecs.co.uk

Help! - Controller for AKM75 motor

Hi, I have looked at several threads regarding this issue but my motor doesn't match the current spec on AKM own website as that indicates the motor cable exiting through the shaft. Mine has the cable coming out of the side of the axle. The forum threads all say the motor is sensorless but my...

www.pedelecs.co.uk

 

[Benjahmin]

To catch up C4 was set at3 already.
With the wheel size thing, somebody's going to have to help me out here 'cos I'm not great at maths. The motor would develop more torque in a 24" but would it do that if I told it it was in a 24 when actually in a 700c? Also I'm trying to keep it legal so need to keep the indicated maximum speed as 15.5.

I wonder if the use of the 328rpm motor in a 700c? wheel is affecting the algorithm? It will hit 25km/h way below 328rpm, doesn't often get above half it's intended operating speed, although 36V vs 48V also makes a difference.

This is what I'm wondering. Certainly at low speeds the motor doesn't sound very happy but that would be 6 and below. Could it be that the low revs feedback to the controller (I assume there is such a thing) prevents higher current feed to prevent heat build up?
The irony here that as the max wattage comes up it's hitting maximum speed so, obviously, ramps down.

The controller is a sine wave 9 mosfet.