Hacking a Rohloff E14 2.0 to work with Bafang M315 (CAN-bus)? Looking for "Shift Sensor" bridge advice
Posted by cockpit_dandruff@reddit | ebikes | View on Reddit | 3 comments
Hi everyone,
I’m currently building a custom cargo bike from the ground up and I’m at a crossroads with the drivetrain. I’m using a Bafang M315 (MM G340.250.C, 48V/250W) mid-drive. It’s the newer CAN-bus variant, which I’ve used on several builds and really like for its reliability.
The Goal:
I want to pair this with a Rohloff Speedhub, but because I’m routing all my brake lines and wiring internally through the frame, I really want to avoid the mess of mechanical shift cables. The Rohloff E14 2.0 electric shifter is the dream—it would make for a much cleaner build.
I know Rohloff recently released the E-14 2.0 DS BAFANG, but documentation is sparse for installing with the Bafang motor. Specifically:
- My M315 has the dedicated 3-pin yellow shift sensor plug. Is this compatible with the product?
- Does the 3-pin shift port on the Bafang provide enough juice to power the E14 actuator?
Any insights from the Rohloff/Bafang experts here?
Lordly_Lobster@reddit
It sounds like the Rohloff E14 2.0 outputs 12V to actuate shifting. If that's the case and the Bafang uses a 5V digital signal to trigger the shift sensor why can't you just use a voltage divider to reduce the 12V signal to 5V and connect that to the signal input of the Bafang shift sensor?
cockpit_dandruff@reddit (OP)
I am trying to confirm the compatibility between the Rohloff E-14 2.0 DC/DC-DS Converter and my Bafang M315. Theoretically, the 'Direct Shifting' (DS) unit is supposed to trigger a torque reduction by sending a signal to the motor’s 3-pin shift sensor port. However, there is a voltage mismatch: the Rohloff E-14 system operates on 12V, while the Bafang shift sensor port operates on a 5V logic circuit. I need to understand how the converter bridges this voltage gap and if this specific 'Direct Shifting' method is compatible with my motor's firmware.
TwoWheel_Detective@reddit
I've routinely used level shifters for interfacing 3.3v boards with 5v from
the ebike controller. It's just a tiny little board for each signal.
For just a couple digital signals, I'll use relays for the interface.
Sounds like an ambitious (but very cool) project.
Do you have a schematic for the Rohloff and the Bafang?
Can't promise anything but I'd take a look and see if I can help.