For a 2WD Bike that is running 2 of the same controllers, can the wires from the LCD be "spliced" into 1 feed? That way to give the pedal assist evenly to each wheel and whatnot?
No, this can't work because the communication between LCD and controller can only happen within one set; each talks to the other, and paralleling them would make the data to/from the LCD unreadable.
If you have the skillsets, you could build an MCU (arduino, etc) setup that takes the data streams from two controllers and "mixes" them, so that the speed, wattage, etc., info from each one is averaged with the other, and then the result sent to the LCD in place of the other data. I am not sure what you'd have to do with the LCD data that gets sent to the controllers.
Simpler would be a switch (which may require powering down the system) to toggle between one controller and the other, switching both LCD and controller data lines.
If it doesnt' require powering the system down, you could make an electronic switch that swaps which controller's data is being displayed in an alternating fashion, so that each would be displayed for a second or two, then the other.
You might be able to simply split the LCD output with a Y-cable to run to both controllers at the same time, to let any button presses you perform on it act on both controllers. But...it's likely that the LCD will require a response from the controller on each action, so it may only work on whichever controller happens to be talking to the LCD at the time. So you may have to swtich the LCD data line along with the controller's, to make sure it works as expected.
gomyles said:
a) both wheels would need to be wound the same to be giving the same speed at a given voltage
It's probably going to share load better that way, assumign the same wheelsize and tires are used, but it's not required. You can play with the http://ebikes.ca/simulator and see how it would work with different or matching setups, using the 2WD option.
I used completely different controllers, motors and wheelsizes on CrazyBIke2, but it was independent throttles for each controller. Would still have worked for my purposes even if I had just one throttle, though.
b) The drain will be significant (30-70 amps depending on controllers)
That is true.
With some setups on the SB Cruiser trike I've seen well over 100A peaks, though it is rarely more than 20A cruising (and it's terrible aero, so a bike would see much less at 20MPH). CB2 was over 80A peak, and maybe 10A or less cruising.
motomech said:
To run two motors at the same time w/ PAS, you would need two sensors,
Probably not. As long as the sensor is powered by only one controller, it's signal can probably be shared by both. As with throttles, the ground line might be an issue, but it's worth a shot before getting complicated.
but my question is, why would want to do that? PAS is all about low-power assist, low enough that you can make a meaningful contribution w/ your legs.
That depends...
On my SB Cruiser trike, with 2WD and a few kW of power (for hauling stuff, mostly, and quick acceleration to 20MPH in traffic situations), I use PAS to control the motor power because my hands randomly go numb, and it's difficult for me to control the throttle when that happens. I still have throttles partly so I can startup easily (havent' found a good way to get PAS startup from a stop; hurts my knees and ankles and someimes hips/back too much under many conditions), and partly so I can use just one motor at a time (left or right) to help steer around corners more sharply. And as a backup for the event of PAS failure (or leg failure leaving me unable to pedal; happens sometimes).
I understand that the signal wire of the throttle can be shared between the two to work in unison.
It may run the motors, but it's likely to have a bad "feel" to it.
Not sure what you mean on that one. I've used both separate throttles, and just one throttle, to run both motors on the trike, and even though they are different controllers *and* different windings, it works just fine.
At the moment I'm using the Cycle Analyst's throttle output to both controllers, just the signal and ground, since there's no need for 5v power from the controllers to the CA. The two throttles (left and right) presently run in complete parallel (all three wires) to the CA's throttle in. (there will be bypass electronics eventually that allow the throttles to *also* go separately to each controller for separate left/right control at a button squeeze, but that's not designed and built yet).
I don't know the exact technical reason, but I believe it's a "feedback" prob., like a ground loop. Folks that have tried using that crude way of running two motors w/ one controller report the best way to do it is to place the two controllers together and run a short common ground wire between them.
Yes, the grounding thing can be a problem, if there's noise induced in the wiring; one controller can be triggered while the other isn't, at very low throttle voltages, for instance.
After many configurations, I settled on two complete systems (2 batt.s, 2 controllers, 2 throttles and, of course, 2 motors).
Except for using a single battery, that's how CrazyBike2 was, and how SB Cruiser was up until a few months ago. Works fine this way, and it actually gives "better" control, once you get used to the separate throttles; I used thumbs, one on each side (matching the brakes on CB2, leftside rear, rightside front).
If it werent' for my worsening hand-numbness problems, I'd probably still only be using it this way on SBC.
