ebrake HWBS and throttle connection

Hi all,

for my next build, I plan not to use a cycle analyst, but a simple throttle connected to the controller (phaserunner).
However, in case water gets in my cheap throttle (or any other stupid thing) I'd like to integrate a HWBS sensor on my brakes (as an extra safety to fault voltage detection in controller).

If I understand correctly this sensor connects the signal wire to ground when the brake is used.
Do you know whether signal is pulled high or wire is "left floating" on rest ?

I ask this question because I wonder if it would be possible to parallel connect the 3 cables of the throttle and the sensor...
If "left floating", the throttle signal would be allowed to drive signal while riding, and when braking the sensor pulls it to ground (whatever the throttle is doing).

That sounds a bit too easy actually

On the controller side, the signal wire is pulled up to 5v with a pull-up resistor. The other wire is a hard ground. When the switch is on, the signal wire is grounded. That means that brake switch off gives a high signal when the controller gives power. Brake switch on gives low signal when the controller cuts the power.

Basically, the HWBS works like a switch. The signal wire effectively becomes a hard ground when the switch is on, and it's open when off. The controller's pull-up resistor will pul it up when connected, so it doesn't need its own one, though it probaly has one anyway.

It's unclear what problem you are trying to solve.

The controller fault detection will pick up the overvoltage and shut down the controller. Normal ebrake functionality does the same. You seem to be trying to protect yourself from very specific controller failures by going for this external wiring - specifically:

• controller fails to detect throttle overvoltage and
• controller ebrake function simultaneously fails but
• the normal "throttle input = ZERO" functionality continues to work properly to stop power.

There is no particular reason to believe (do a search here on ES or wherever) that either of these two controller failure modes are common and it is certainly more unlikely that they will occur together while the rest of the throttle functionality continues to operate properly. On the face of it, this very specific failure mode seems to be as likely as being hit by lightning.

If you want to go after controller failures, then do it the 'standard' way and address all controller failures, not just this particular scenario: install a thumb-operated kill switch that turns off the controller 'ignition wire'. This shuts down the processor and the controller goes instantly brain dead (no power possible) no matter what has failed.

This has been thought out and the controller already has the connections to do more than you are trying to address - just use them as designed.

But - if you really want to pursue this, then you can hook your ebrakes to the Phaserunner common throttle/ebrake input and then hook your throttle there through a 1K resistor. Hitting the ebrakes will drag the throttle/ebrake input into the regen region and cut the power but the throttle output will be applied across the resistor instead of simply being shorted to GND by the ebrakes - which is not nice. The resistor will limit the current that a hall throttle can supply to about 4ma which should be within the ability of a HWBS Open collector output to bring to Gnd.

• FWIW - The Phaserunner throttle and ebrake inputs are normally tied together and there are both pullup and pulldown resistors in play so the input voltage that the controller sees with nothing connected at all is in the 1V region - NOT ebrakes=5v and throttle=Gnd as in other controllers. This is so there can be a continuity of proportional fwd power and proportional regen from the same signal. You can get the more conventional situation only by separating the throttle and ebrake inputs.