Key-Disp KD831 User manual

1
Product name and Model
Electric Bicycle Intelligent Display,
Model: KD831.
Specifications
●24V/36V /48V Power Supply
●Rated current: 10mA
●The maximum working current: 30mA
●Off-state leakage current: <1μA
●Working temperature: -20 ~ 60 ℃
●Storage temperature: -30 ~ 70 ℃
Appearance and Size
Display appearance and dimensional drawing (unit: mm)

2
Function and Button Definition
◆Function Summary
KD831 has a lot of functions to meet the riders’ needs. The indication elements are
●Intelligent Battery SOC indicator
●Assist level adjustment and indication
●Speed indication
●Motor-output indicator
●Trip time
●Trip distance and Total distance
●The push-assistance function and indicator
●Lighting control and indicator
●Error Code indication
◆Button Definition
There are four buttons, power button, mode button and plus & minus buttons on KD831 display. In
this manual, we use words ON/OFF, i, +, - to represent these four buttons. The top edge and the
bottom edge of the display will be working as “plus” button and “minus” button. The touch feeling is
like a rocker switch.
Install Instructions
KD831 can be mounted on the left side of handlebar close to its grip. Adjust the angle for a
good screen view. Cut off the power before connecting the corresponding connectors between
display and controller.
General Operation
◆Switching the E-bike system On/Off
To switch on the E-bike system, hold the ON/OFF button for 2s.
To switch off the E-bike system, hold the ON/OFF button for 2s.
When E-bike system is switched off, the leakage current is less than 1 μA.
* if sticky button for ON/OFF or push assist (-button in KD831 serves as push assist function
button) or overvoltage or short-circuit MOS tube happens, the corresponding error code will be
indicated on the display. Please refer to attached list 1 for more details. If user operates the display
improperly such as over pressing the on/off button or pressing on/off button and – button
simultaneously, turn off the display and restart it.
■In case of no use of bike for approx. 10 minutes, the display switches off automatically.

3
◆Main menu interface( function display page)
After the E-bike system is switched on, the display shows current speed by default. Press i
button to switch between indication functions below:
Current Speed (Km/h) → ODO(Km) → Trip Distance (Km)→Trip Time (Min) → Average
Speed (Km/h) → Max Speed (Km/h) →Power(W).
Indication items cycle interface
◆push assist function
To activate the push-assistance function, press and hold the -button. After 2 seconds, the E-
bike will go on at a uniform speed of 6 Km/h and “ ” is shown on the screen at the same time.
The push-assistance function is switched off as soon as you release the -button.
Push assist function
■Push-assist function may only be used when pushing the E-bike. Be aware of danger of injury
when the wheels of E-bike do not have ground contact while using push-assistance function.

4
◆switch the bike light on/off
When light is off, after long pressing + button, display sends command to controller to
turn on the light and the light icon is shown on the display screen. When light is on, after
long pressing + button, display sends command to controller to turn off the light and light
icon disappears.
Light on indication
◆assist level selection
Press +/- button to increase or decrease the assist level and change the motor output
power. Level zero means no power assist output.
Assist level selection
◆motor power indication
The motor output power can be indicated by below interface.
Motor power indication
◆error code indication
The components of the E-bike system are continuously and automatically monitored. When
an error is detected, the respective error code is indicated, refer to the detailed definition of
the error codes in Attached list 1.

5
Error code interface
Settings
When speed is zero, at the main menu, long press i button to enter the setting interface.
Press +/- buttons to choose the setting item. Press i to enter the corresponding setting or info page.
Long press i button to exit the setting items interface and return to the main menu page. If there’s
no operations within 2 minutes, the display exit the setting page automatically.
Setting items interface
◆Trip Distance Clearance
Clr Trip means trip clearance. Press the +/- button to choose YES or NO. The default value is NO.
To clear a trip, choose YES and press the i button to confirm. The screen says 'OK' and returns
to the Settings interface.
Trip distance clearance

6
◆Unit Mile/KM toggling
Unit represents unit settings. The default value is Metric ‘KM’
To toggle unit, press +/- until the desired unit is displayed.
To store a changed setting, press the ibutton to confirm. The screen says 'OK' and then returns
to Settings interface.
Mile and Kilometer Toggling Interface
◆Backlight Brightness Settings
Bright represents backlight brightness settings. Level “1” is the low brightness, Level “3” is high
brightness. The default level is “2”.
To change the backlight brightness, press the “+” button or the “-” button to choose the desired
brightness.
To store a changed setting, press the “i” button. The screen says “OK” and returns to previous
menu interface.
Backlight settings
◆wheel size setting
Wheel refers to wheel diameter settings. Press i to enter the setting page. According to new
EU norms, WD value is not settable. Press i button and screen says OK and returns to the setting
page.
Wheel size setting

7
◆speed limit info
Speed means speed limit. Press i button to enter the speed limit info page. According to new
EU norms, the speed limit value is not settable. It is only for your information. Press i and screen
says OK and returns to the setting page.
Speed limit info
◆Battery power bars settings ( voltage segments)
Vol Bars refers to battery power bars settings. Press i button to enter the setting page.
Press +/- to change the values for each power bar. And press i to confirm and move the next
power bar settings. After 5 values are completely set, press i button to save the setting and
screen says OK and return to the setting page.
Battery power bars settings
助
◆Assist level
Assist level mode selection
Max Pas refers to PAS parameters settings. Press i button to enter the setting page. 8 assist
level modes are 0-3 、1-3 、0-5、1-5 、0-7 、1-7 、0-9 、1-9. Press +/- to choose the desired
mode and press i button access to the corresponding assist level ratio info interface.
Assist level mode selection

8
PAS level ratio info
PAS level ratio refers to the power assist that can be engaged by a certain level. According
to new EU norms, the value is not settable. Long press i button to return to the setting page. The
PAS level ratio defaults are in the attached list 2.
PAS level ratio info
◆power-on password settings
Password means power-on password settings. Press i button to enter “P2” interface
and correctly input the current 4-digit password to get to the power-on password setting
page. The default password is “1212” if not specified by the customer. At password setting
interface, the first item is “password disable”, the second item is “password enable” and the
third item is “change password”. Press +/- button to choose your desired item and press i to
confirm(operation for changing a password is identical to inputting a password). The screen
returns to the setting page after operation is done.
Power-on password settings
◆Current limit
Cur Max means current limit. Press i button to enter the info page. According to new EU
norms, current limit is not settable and it is only for your information. Press i and screen says OK
and returns to the setting page.
Current limit info

9
◆PAS sensor magnet numbers
PAS Pole means the number of magnets in the PAS sensor. Press i button to enter the info
page. According to new EU norms, PAS is not settable and it is only for your information. Press i
and screen says OK and returns to the setting page.
PAS info
◆Speed Sensor magnet numbers
SS Pole refers to the number of magnets in the speed sensor. Press i button to enter the info
page. According to new EU norms, SPS is not settable and it is only for your information. Press i
and screen says OK and returns to the setting page.
SPS info
◆Slowly Start Up
Slow SP means slowly start up. Press i button to enter the info page. According to new EU
norms, SSP is not settable and it is only for your information. Press i and screen says OK and
returns to the setting page.
SSP info
Factory settings
When speed is zero, at the main menu interface, long press the i button and + button to enter the
factory settings page. Choose “Yes” to restore to factory settings. The screen says OK and return to
main menu page.
Factory settings

10
Quality Assurance and Warranty Scope
ⅠWarranty
1).The warranty will be valid only for products used in normal usage and conditions.
2).The warranty is valid for 24 months after the shipment or delivery to the
customer.
ⅡOthers
The following cases do not belong to our warranty scope.
1).The display is demolished.
2).The damage of the display is caused by wrong installation or operation.
3).Shell of the display is broken when the display is out of the factory.
4).Wire of the display is broken.
5).The fault or damage of the display is caused by the force majeure (e.g., fire,
earthquake, etc.).
6). Beyond Warranty period.
Operation Cautions
●Be cautious. Don’t attempt to disconnect the connector when battery is on power.
●Try to avoid hitting.
●Do not modify system parameters to avoid parameters disorder.
●Make the display repaired when error code appears.
wire connection layout
Standard connector wire sequence
Controller end
Display end
Mating connector to display end
Standard wire sequence table
Wire no.
Wire color(standard)
Function
1
Red(VCC)
Display power
2
Blue(K)
Controller power wire
3
Black(GND)
Display GND
4
Green(RX)
Display-RX
5
Yellow(TX)
Display-TX
■Some products have pin wire connection with waterproof connectors and users can not see the
wire color inside the harness.

11
Attached list 1: Error code definition
Error code
Definition
21
Current fault
22
Throttle fault
23
Motor absence-phase fault
24
Motor hall fault
25
Brake fault
30
Communication failure
31
Short-circuited MOS tube
32
Sticky ON/OFF button
33
Sticky push-assist button
34
Over-voltage
Attached list 2: PAS level ratio defaults
Level
1
2
3
4
5
6
7
8
9
PAS range
Selection
0-3/1-3
50%
74%
92%
—
—
—
—
—
—
0-5/ 1-5
50%
61%
73%
85%
96%
—
—
—
—
0-7/ 1-7
40%
50%
60%
70%
80%
90%
96%
—
—
0-9/ 1-9
25%
34%
43%
52%
61%
70%
79%
88%
96%