Wheel size selection in BAC-601.

[MacEV]

In my bike I have 27.5 inch wheels.
The same setting I set in the display and the home-to-work route is about 5 km.
In my other previous electric kit in the display settings was the tire circuit and the distance was 6.3 km.
Even after setting the maximum wheel size (30 inches) the distance only slightly approached those 6.3 km.
In my Magic Pie 4 kit I have no "wheel diameter adjusting factor setting" option.
How do I correct this?

[Bikemad]

If you haven't saved the wheel size settings after selecting your wheel size, the unit may still be set at the default 20" wheel.

7 Save Settings Parameters
After finishing the settings, short press "MODE" button and confirm the current
settings and then enter into next setting interface.
Long press "MODE" will automatically save the parameters and exit.

My early BAC-601 does have the "SE2 Wheel Diameter Adjusting Factor Setting" to adjust the accuracy of the wheel size:

6.2.2 SE2.Wheel Diameter Adjusting Factor Setting
Setting the wheel diameter adjusting factor can obtain the accurate speed and
mileage value through "UP" and "DOWN" button.
The default setting is 1.00 and minimum is 0.7 and maximum is 1.3.
(Note:actual wheel diameter = wheel diameter X wheel diameter adjusting factor )

This should allow you to increase or decrease the distance and speed readings up to 30% in addition the the default wheel size setting. (More details can be found in the User's Guide.)

If your later Display unit does not have this adjustment, and the correct wheel size was definitely saved, you could try changing the setting to mph instead of km/h and select smaller wheel sizes until the speed and distance read correctly.

Alan
 

[MacEV]

After setting the wheel size and pressing the "mode" button, the settings are saved.
I remembered that I compared the speed on the display with the speed of the gps and the readings were very close, but still the distance was underestimated.

Now I'm trying to change km / h to mph and let me know if it is improving.

Thank you for the advice and best regards.

[Bikemad]

If the speed is reading correctly but the distance is not, then there must be a problem with the coding of the software, as the distance and speed should both be directly related to the wheel size.

If you adjust the settings to get the distance reading correctly, I think it will then upset the speedometer reading. 

When I read your initial post, I wrongly assumed that both the speed and the distance readings were incorrect, not just the distance.

Alan
 

[MacEV]

Is this wrong encoding occurs in the display module?
If I give the display module a guarantee, is there a chance of repair or replacement for a good one?

[Bikemad]

I don't know whether the Display unit does all the calculations or whether some of it is done within the controller's firmware.

I'm not sure how the display would know the difference between Smart Pies and Magic Pies if it simply used a high/low Hall sensor output pulse for speed reference, as the Smart Pie would produce 20 pulses per revolution and the Magic Pie would produce 28 pulses.

As the same display is used for both motors, there must be something in the controller's firmware that produces approximately the same signal output in relation to the wheel rpm for each motor.

I would logically expect any variation between distance and speed to be solely due to the display unit calculations, but logical programming cannot be guaranteed, therefore it is also possible that a mistake in the calculations within the controller's firmware could also be causing it. 

To be honest, I have never checked my distance readings against any other source, and as I only use that bike for short (mainly off road) trips, it's possible that my distance figures could be wrong too. 

Alan