Budget controller /display kit

[Mappier]

Hi all,
I've bought a replacement controller and display kit to go with a 36v battery and 250w Bafang crank drive motor. On the rear of the display is a sticker saying 24v Passed. The voltage
getting to the display is 41.3v(battery fully charged); will this fry the display?

 

[vfr400]

If the display came with the controller, it should be OK. Most of those displays have a setting for the voltage, so make sure you download the manual.

 

[Nealh]

That controller say's it's a dual voltage 24/36v one so their is no issue to worry about.

 

[Mappier]

Thanks. Everything going together pretty well ok; I had to swap over two of the phase wires to get the motor to run. The kit includes PAS components but I want to use the existing set-up integrated into the Bafang motor casing. However, the red and blue wires going to its SM connector from the controller are in a different order to those from the controller. I'm attempting to swap over the red and blue pins on the connector but having a lot of trouble probably because they have been in situ since the bike was built in 2013. Failing swapping over those pins would it be permissible to swap the colours in the newer connector on the transformer side?

 

[Mappier]

I managed to extricate the three male pins from the SM connector by completely destroying the plastic housing and inserted them into a new one. Still no PAS.
I removed the crank and the original PAS sensor. The magnets are housed inside an aluminium cage about 2" diameter, this requires a special tool to remove so I left it in place.
I then fitted the PAS sensor and magnet ring that came with the kit. It worked, getting up to 30kph showing on the display but as you can see in the picture once the crank is fully home the magnet disc will foul the motor casing; which is why I would prefer to use the original PAS setup.

 

[vfr400]

It's not going to work very well unless you only use a throttle, which is a pain. That controller uses speed control for the PAS, which gives a different crank speed for each level. For a crank motor motor, you need current (power control), which you get with a controller from KT.

 

[Mappier]

Thanks for that info. The kit included a speed sensor which isn't fitted yet; do I need the speed sensor and the PAS set-up?

 

[vfr400]

Thanks for that info. The kit included a speed sensor which isn't fitted yet; do I need the speed sensor and the PAS set-up?

Yes, you need the wheel speed sensor, otherwise the LCD will show the wrong speed, which will be based on motor RPM, which will be too high and might shut down the system. If you disable that in the settings, the controller might go to sleep after 5 minutes unless you have a setting to switch that off.

PAS is optional, as are brake sensors.

 

[Mappier]

By setting the wheel diameter via the LCD does that not give a fairly accurate speed indication?

 

[Nealh]

By setting the wheel diameter via the LCD does that not give a fairly accurate speed indication?

It does but it needs a speed sensor to pick up the signal from to get the rpm/cadence, the setting can't predict speed from thin air alone.

 

[Mappier]

I fitted the King Meter speed sensor but it only shows the speed when the motor is running?
I lift the rear wheel and the half twist throttle takes the speed up to 17mph, as soon as I relax the grip and the motor cuts out indicated speed drops to zero. Is this normal?

 

[Nealh]

Some displays have a setting where you can make changes so that speed registers always even when freewheeling, my KT's have this option. I don't know the settings for the Brainwave so can't comment on if it has one.

 

[vfr400]

I fitted the King Meter speed sensor but it only shows the speed when the motor is running?
I lift the rear wheel and the half twist throttle takes the speed up to 17mph, as soon as I relax the grip and the motor cuts out indicated speed drops to zero. Is this normal?

That means that the controller isn't using the speed sensor you fitted. Either you wired it up wrong or you did the settings wrong.

 

[Mappier]

Sorted thanks. I went into the settings (P03 - 0 on the Brainpower controller) and am now getting MPH all the time.

 

[Mappier]

A couple of things still don't feel right. Lifting the rear wheel and using the throttle the indicated speed is 16mph but when I'm sat on the bike it only gets up to about 9mph under throttle, I'm 12st BTW. Also, I can be riding along under PAS and motor power is cut momentarily then picks up again which can feel very disconcerting. I read it could be an unbalanced battery so I left the battery charger plugged in and switched on for a few hours after the battery full light was on.

 

[vfr400]

A couple of things still don't feel right. Lifting the rear wheel and using the throttle the indicated speed is 16mph but when I'm sat on the bike it only gets up to about 9mph under throttle, I'm 12st BTW. Also, I can be riding along under PAS and motor power is cut momentarily then picks up again which can feel very disconcerting. I read it could be an unbalanced battery so I left the battery charger plugged in and switched on for a few hours after the battery full light was on.

the controller controls the crank speed, not the bike speed. The crank should spin to about 75 rpm. What are you getting? The bike speed depends on which gear you're in

 

[Mappier]

When I'm under way the display indicates the amount of power being consumed, see picture. Under load on a slight gradient the number of bars showing increases to maximum then motor cuts out

 

[vfr400]

Do you have the two self-learning wires and did you do the self-learning procedure?

 

[Mappier]

Yes the self-learning wires are present but I haven't used it. I didn't receive any instructions with the kit but I did find a piece on Youtube about how to use self-learning.
When I first powered up the kit the motor just clicked a bit but didn't rotate so I swapped over two of the phase wires and the motor then started normally; thinking back should I have used the self-learning wires?
Thanks for your time. Jim

 

[vfr400]

Do the self-learning. You might have a false positive connection sequence that works but not efficiently.