BionX: Where Is The Controller?

[PeteCress]

Until today, I was thinking it was in the battery case.

But viewing a YouTube video on the innards of the BionX motor, I *think* I heard the narrator say there was controller in the motor.

Motor seems more logical in the context of batteries having tb replaced and the need to maintain certain settings.

Anybody know for sure?

Tangental question: If the controller *is* in the motor, does that mean that other batteries (of correct voltage) can be used with BionX motors?

 

[deardancer3]

Welcome.


The Bionx "controller" is a distributed controller interconnected by the CAN interface buss. Most motor functions are in the motor casing, with some control functions in the battery housing module, and most human interface stuff in the console.

Search E-S for Bionx, there are quite a few interesting discussions.

The Bionx is a closed, proprietary system. almost everything has to be purchased thru bionx, outside pieces not made by Bionx wont work.

D

 

[alan]

I'm guessing that BionX has the electronics distributed in three components, the hub, battery, and display, with the I2C bus (older models) or CAN bus (newer models) connecting all three as follows:

The hub contains the motor, the hall sensors, the torque sensor, the power switches (commonly referred to as the motor controller), and additional electronics, including a bus interface, hall sensor interface smarts, torque sensor interface smarts, and maybe more, such as a temp sensor, and probably includes the core speed control logic.

The battery contains the cells, the battery management smarts, including the charger interface and discharge and cell balance and temperature protection circuits, as well as a bus interface and probably the main system control logic and flash memory. The main control smarts stores and acts on the dozens of programmable settings of the BionX system.

The display includes the readout display, drivers, and backlight, the input pad and interface, the throttle sensor, the brake sensor interface, and the bus interface,.

Also, in addition to the 6 wire bus (dual differential signals plus power and ground) that connects the three main components, there are two power leads between the battery and the hub, and a two wire cable between the display and the brake switch.

That is, my expectation is that most of the system logic and memory that interfaces to the motor (power controller and torque sensor), BMS, and display (readout/input pad/throttle/brake switch) is inside the battery. It is possible that some or all of this logic and memory is in the hub or display, or split between the three components.

I hope I did not make the BionX system seem overly complex. My opinion is that it is extremely well engineered with minimal complexity for the exceptional pallet of features and ease of use (installation, programming ease and riding simplicity). Most of the elements above (except for the bus, torque sensor, multi-function input pad and display, and the higher level logic and memory electronics) are found on most ebikes. On the other hand, the very tight integration of so many added features makes interchanging non-BionX components such as batteries difficult.

One important feature I have not seen mentioned elsewhere in these threads is that by putting the power switches (motor speed controller) inside the motor hub, the wire lengths between the controller and motor windings are minimized. This is far more important than most may realize. On the many RC planes I have built, efficiency and responsiveness of the brushless motors degrade very quickly as the lead length to the speed controller (ESC) increases; and every inch matters.

-- Alan

 

[PeteCress]

... almost everything has to be purchased thru bionx, outside pieces not made by Bionx wont work.

Thanks Alan.

Thanks DearDancer.

You have both addressed my real agenda: the possibility of mixing and matching.

BionX initially attracted me bco the seemingly-superior UI and the reportedly smooth/seamless nature of "assist" mode.

But I subsequently got spooked by:

• Two accounts of the system going into full-power mode after the user hopped a curb
  
• The "hitting the wall" phenomenon where all assist cuts out suddenly @something like 19.5 mph
  
• The $1,200 battery replacement cost

Accordingly I wound up committing a lot less money via the e-BikeKit.com setup (front-wheel drive). Noise was a potental deal breaker for me. Some of the units I saw/heard on YouTube were unaccepably loud. The guys behind eBikeKit were available face-to-face so I was able verify that their product met my noise requirements.

I figure I'll play around with this one for awhile and then upgrade to what I will eventually realize that I really want.

Right now, I suspect that will involve more stealth, less weight,and possibly rear-wheel instead of front-wheel drive..... but only time will tell.

BionX still sounds like the most elegant solution and I'm guessing that without those short wires and that pressure sensor on the axle, nobody is going to even come close to the what I hear is the smoothness of BionX's assist mode.

 

[deardancer3]

If sales continue at a decent clip, I expect some enterprising folks to start a business fixing and swapping Bionx batteries.

The power drop off at the max speed limit is not abrupt on a correctly set up system.


Dont think I would go curb hoping with a Bionx. Even still with the thousands of Bionx's in North America, 2 is not a big number.

But if you want to tinker, Bionx is not the system.

d

 

[dennis]

Until today, I was thinking it was in the battery case.

But viewing a YouTube video on the innards of the BionX motor, I *think* I heard the narrator say there was controller in the motor.

Motor seems more logical in the context of batteries having tb replaced and the need to maintain certain settings.

Anybody know for sure?

Tangental question: If the controller *is* in the motor, does that mean that other batteries (of correct voltage) can be used with BionX motors?

Ken's friend who worked on my pre-2009 Bionx battery box may be able to answer your question...you may want to try to send him a PM ...this http://www.endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=2227
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=7813 ...yes, you can use other batteries...there is a slight glitch though... see http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=5347&start=75 and see post by kosherrav on 09/06/2009 http://visforvoltage.org/forum/5360-bionx-battery-replacement

see my latest post on Dec 19, 2009 for an interesting update http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=5347&start=90

 

[deardancer3]

Interesting developments for the Bionx Battery dilema.

another thought--- People have been using the charging port for an aux batt input . no permanent modification which is nice for some systems .

the soft pack setup has some disadvantages, but, is really easy to modify.

Keep up the info.


d

 

[PeteCress]

...and see post by kosherrav on 09/06/2009 http://visforvoltage.org/forum/5360-bionx-battery-replacement

Kosherrav's post seems to beg a question: Once BionX battery dies, could the BionX battery stuff just be removed (to save weight) and an external "Brand X" battery wired in?

 

[deardancer3]

for NIMH in the soft bag, yes.

The hard shell dictates some size contraints that a soft bag does not.

I am not good enough on Lith to advise on it yet.

d

 

[silentflight]

It is not very difficult to replace the battery cells on your own. It does require re-using the electronics/board from inside the battery case and supplying your own charging system. You can choose your voltage, chemistry and amphours in return for your efforts, though.

It is also possible to overvolt both the 24 and 36 volt systems to improve performance. This can make a bionx more powerful and faster, increasing no-pedal max speed by 7-10 mph. This is more difficult on the 36 volt system as it does not like to power up if the voltage is too high, but this can be overcome.