Danger: High Voltage & Safety
Never raise the "Limit Current (A)" setting beyond the hardware safety limit of your motor model. Exceeding safe current limits will blow the controller MOSFETs and melt internal wiring, creating a fire hazard.
Required Parts & Tools
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Replacement Parts Needed
- Bafang Configuration Tool Software (Free download)Free
The official programming software utility used to read, edit, and write settings to the Bafang controller.
Tools Required
- Bafang USB Programming Cable (with 5-pin HIGO connector)$12 - $18
Interfaces the green 5-pin display connector on the motor harness to a standard USB-A port on a computer.
- Windows PC (or Android device with USB OTG adapter)N/A
Used to run the configuration software (or Speeed app on Android) to edit the controller settings.
DIYStep-by-Step Instructions
- Step 1 of 6
Disconnect the Display from the Harness
Ensure the e-bike battery is turned off. Locate the green 5-pin waterproof HIGO connector on the main wiring harness near the handlebars (it connects the display to the main cable). Pull the connectors straight apart. Do not twist them, as this can bend the tiny pins inside.
Schematic FIG. 1DIYPEV Technical LabUnplugging the green 5-pin waterproof display cable from the wiring harnessReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale) - Step 2 of 6
Connect the USB Programming Cable
Plug the 5-pin male end of your USB programming cable into the female green connector on the wiring harness coming from the motor. Plug the USB-A end of the programming cable into your computer (or into an Android phone via a USB-OTG adapter). Turn on the e-bike battery to supply power to the controller.
Schematic FIG. 2DIYPEV Technical LabConnecting the Bafang programming cable to the green wiring harness plugReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale) - Step 3 of 6
Initialize the Configuration Software
Open the Bafang Configuration Tool software on your PC. Select the correct COM port (you can find this in Windows Device Manager under Ports). Click "Connect". If successful, the status bar at the bottom will turn green and show "Connected". If it fails to connect, verify the COM port driver (usually CH340 or PL2303) is installed.
Schematic FIG. 3DIYPEV Technical LabConnecting the Bafang programming software on a Windows computer screenReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale) - Step 4 of 6
Read Existing Controller Settings
Before modifying any settings, click the "Read" button under the "Basic" tab, the "Pedal Assist" tab, and the "Throttle" tab. This downloads the current configurations stored in your motor's EEPROM memory. Save these original settings to a file (File -> Save) as a backup in case you need to revert to factory defaults.
Schematic FIG. 4DIYPEV Technical LabClicking the Read button in the Bafang programming program windowReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale) - Step 5 of 6
Modify Key Parameters for Smoother Performance
Adjust your desired settings. To fix the jerky PAS start, go to the "Pedal Assist" tab and reduce the "Start Current %". To prevent the motor from losing power at high pedaling speeds, increase the "Keep Current %" from the stock 60% to 85% or 90%. To unlock speed restrictions, set the "Speed Limit" to "By Display" or "40".
Schematic FIG. 5DIYPEV Technical LabAdjusting parameter numbers in the Bafang configuration utility interfaceReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale) - Step 6 of 6
Write Settings and Reconnect Display
For each of the three tabs (Basic, Pedal Assist, Throttle), click the "Write" button. The software will display "Write Success" for each tab. Turn off the e-bike battery. Unplug the programming cable and reconnect the display cable, aligning the index marks on the green plugs. Turn the battery back on and perform a test ride.
Schematic FIG. 6DIYPEV Technical LabPlugging the display cable back into the green wiring harness socketReference Blueprint SchematicAlt description tag verifiedScale: NTS (Not To Scale)
Understanding Bafang Controller Parameters
The Bafang controller firmware contains dozens of editable values split into three distinct categories. The "Basic" tab configures system limits, such as battery low voltage cut-offs and maximum current. The "Pedal Assist" tab governs the characteristics of the motor's response to pedal motion. The "Throttle" tab configures how the thumb or twist throttle behaves, allowing you to override PAS settings or map throttle inputs to speed or torque.
Below is a quick-reference table listing the most critical parameters, their stock values, and recommended settings for a tuned, high-performance profile.
| Parameter Name | Default Value | Recommended Setting | Effect of Modification |
|---|---|---|---|
| Limit Current (BBS02) | 25 Amps | 25 Amps (Max safe limit) | Do not increase. Safe limit for BBS02 controller heatsink. |
| Limit Current (BBSHD) | 30 Amps | 30 Amps (Max safe limit) | Safe peak current for continuous BBSHD operation. |
| Start Current (%) | 20 - 30% | 10 - 15% | Reduces the initial torque jolt when you begin pedaling. |
| Keep Current (%) | 60% | 80 - 90% | Maintains motor power at higher pedaling cadences. |
| Start Degree (Signal) | 4 | 2 | Reduces pedal assist engagement delay from 1/3 turn to 1/6 turn. |
| Speed Limit | 25 km/h | By Display Command | Allows the handlebar display menu to control top speed limits. |
| Throttle Mode | Speed | Current (Torque) | Changes throttle from cruise-control speed steps to torque control. |
Tuning Throttle for Torque (Current) Control
By default, Bafang controllers configure the throttle in "Speed" mode. In this mode, holding the throttle at 50% tells the controller to spin the motor at exactly 50% of its maximum speed, regardless of how much force it takes. This makes the throttle feel jerky and act like a switch. Changing the throttle mode to "Current" (also known as Torque mode) maps the throttle position to power output instead. Squeezing the throttle 20% delivers 20% of the motor's power, making it incredibly smooth and easy to modulate, especially when negotiating tight off-road trails.
Backup Your Configuration first
Always backup your factory settings before writing any changes. Many Bafang motors ship with slightly different internal firmware versions, and loading a generic template from the internet can occasionally overwrite calibration offsets, causing error codes or erratic motor behavior.