Noob user questions about Pro Kit 902

[Micha]

Hi All,

New to the community and proud owner of a 20" folding bike and Pro Kit 902 added to it.
I bought the kit in this link:
http://www.devi-motion.com/webshop/e-bike-kit/p-1/D1000040--prokit-902-36v-250w-20-%22--front.html

I also added a PAS sensor, and was wondering about controlling the motor speed (or pedal support) without the throttle in steps.

- Can I add a display to the controller?
- Which connections would I use, I assume the same as where the throttle is connected to?
- Can I also connect a LCD display like the one in this link?
http://www.ebike-battery.de/product_info.php?info=p12_king-meter-j-lcd-display.html
Or can only a simple led display be connected
http://www.rat-holland.nl/Onderdelen/Displays/Display-009-set

- Is it also possible to program the controller?


Thanks,

Micha

[Bikemad]

Hi Micha andto the forum.

Unfortunately, GM do not have a display unit which works with their external controllers apart from the Cat Eye speedometer, but this is simply a cycle computer and cannot be used to control the motor.
 
The BAC-601 Smart Display unit is only compatible with the later internal vector controllers fitted to the Smart Pie 4 and Magic Pie 4 and it uses a separate connector on the motor harness which is also used for programming:


I don't think that either of the two display units that you previously mentioned will be compatible with the GM external controller, as they are each meant to be used with their own specific controllers.

An alternative display unit which should work with the external controller is the very popular Cycle Analyst.

The GM external controllers can be programmed using the PI-200E USB cable shown on the left:



Alan
 

[Micha]

Thanks for the reply Alan.

I think the cycle analyst would be a welcome add-on if I want to read out the Voltage and battery status, and offer more the a display and programming cable would for a bit more in price.

[Micha]

A question about the cycle analyst.
Which version do I need?

I see 3 versions:
- Stand alone
- with speedometer
- without speedometer

I don't need the speedometer, as the mototr has hall sensors, but do I need the remote shunt (stand alone)?

[Bikemad]

You will need the stand alone version with the external shunt, but I'm not sure whether the speedometer sensor is required or not.

As you've already mentioned, you should be able to use one of the hall sensor signals for the speed input, but I don't know how easy it is to correctly calibrate the speed from the hall sensor signals, but as the minimotor (Pro Kit 902) only has 20 magnets, I think it should be possible.

You might want to do some more reading on the forum and also check out Gary's website for additional information on the Cycle Analyst. 

Alan
 

[GM Canada]

I answered a similar question in email earlier today. Maybe this can help...

Waht do I need to build a true pedal assist that senses how hard you pedal?


To do this you would need a cycle analyst 3 with thun sensor for true detection of how hard you are pushing on the pedals.
 
http://www.goldenmotor.ca/categories/Cycle-Analyst/Cycle-Analyst-Thun-Sensor-Packages/
 
Then a 902 Kit as they freewheel with zero resistance. This is a link to 26 inch rear.
 
http://www.goldenmotor.ca/products/26-Inch-36V-Rear-PRO-902-Conversion-Kit.html
 
The motor is 250 watts so it would give a small assist. If you find its not enough you can go with both a front and rear kit. Together you would have 500 watts.
 
I built two similar bikes for myself.
 
If you look at the top picture on this page it is a 29er I built with the CA3/Thun package
 
http://www.goldenmotor.ca/pages/My-Ebikes.html
 
The bottom picture is a 700c with dual 902 mini motors.
 
You can click on the pictures to see the builds.

The Speedo makes life simple for using the Cycle Analyst.

Gary

[Micha]

Thanks for the replies Alan and Gary.

I use the folding bike for commuting and want to travel as light as possible when going up-down the stairs and in/out the trains, so that's why I went for the 250W mini motor, also for street legal purposes.

I believe I saw the YouTube videos from the two 902's, Gary... Going very fast 

For now I ordered the programming cable just to see what settings the motor came with, and also will get a turnigy wattmeter to do some readings within a few days.
Perhaps as a later investment I will go for the cycle analyst 

[Micha]

I just received the programming cable, and it appears the controller was set at factory settings, see attached picture.

I bought a 36V motor, so find it strange the controller is set at 24V.

I have a 36V battery, I assume setting the controller to 36V will only have a positive effect (?)
Can anyone tell me what the effect will be?

Thanks,

Micha

[Bikemad]

Hi Micha, Those current settings are much too high for the minimotor and could allow it to overheat if loaded too much.
It should be set to around 7-10 Amps continuous and about 15-18 Amp max, but with the reduced load on the motor due to the 20" wheels, you hopefully won't be straining it too much.

Many owners found the torque was better using higher voltage batteries if the controller was set to 24V, and as long as your battery has its own low voltage protection you should be fine running on the 24V setting.

Are you sure the current settings were that high before you clicked on the "Factory Setting" button?

Unfortunately, the freewheel mechanism inside the minimotor means that it cannot make use of the Reverse and Regen functions, but at least you are now able to set the current setting to suit your motor and adjust the Pedelec assistance too.

Alan
 

[Micha]

It was set at the shown settings yes 

I will do some additional tweaking. Today I set it at 36V 10A, 25Max, it sure feels less responsive, so will try 24V again.

[Micha]

Ok, so I recently purchased a wattmeter (turnigy) to be able to do some measurements.

I also purchased a 36V 18Ah Lithium battery (most likely Li NCM, still have to ask which lithium cells they used).

I have set the BAC 28X controller to 9A cont and 15A peak.
Still the wattmeter only measures 9A peak during every trip I take, even short uphill tracks.

So my question is what is limiting the amps, is it the controller or can also the BMS limit the amps, and how can I determine this?

[Bikemad]

Try raising both of the current settings and see if the Amps increase.

Alan
 

[Micha]

Hi Alan,

Forgot to mention I already did that. Raised to 12A cont, and 18A peak, has no effect alas.

[Bikemad]

Hi Micha,

If the power is not limited by the software it must be limited by the controller hardware, perhaps it has a thinner/longer shunt wire than the other controllers, or it could be that the small wheels on your bike are not placing the motor under a high enough load to draw higher amps.

According to Gary's website, the controller for the 902 motors is only rated at 10 Amps as against the 25 Amps for the other motors and you should also remember that the mini motor is only rated as a 250 watt motor.

Drawing 9 amps at 36 volts would consume 324 watts, which equates to an output power of 259 watts at 80% motor efficiency, which is already more than the rated power for the minimotor.

I think the controller current is probably limited for a very good reason, because if you push too much current through the mini motors it can strip the teeth off the nylon gears and also overheat the windings which can melt the insulation on the Hall Sensor wires resulting in a short circuit:



Perhaps the current setting is correct as it is.

Alan
 

[Micha]

I also contacted the goldenmotor distributor if they limited the controller.

The reason I need to know what is causing the limit is that I'm looking to upgrade the mini for a pie or prokit 901 hub, or a leafmotor hub, hence the larger battery I purchased first.
But if the controller limits the current than I need a new controller as well.