Key-Disp KD51C User manual

Content
Content 2
Product Name and Model 1
Specifications 1
Appearance and Size 1
Function Summary 2
◆Function Summary 2
◆Functional Area Distribution 3
General Operation 3
◆Switching the E-bike System On/Off 3
◆Display Interface 3
◆Switching Push-assistance Mode On/Off 4
◆Switching the Lighting On/Off 4
◆Assistance Level Selection 4
◆Battery Indicator 5
◆Motor Power Indicator 5
◆USB Connection Indicator 5
◆Error Code Indication 6
General Settings 6
◆Trip Distance Clearance 6
◆Backlight Contrast Settings 6
◆Unit km/mi Conversion 7
General Parameter Settings 7
◆Wheel Diameter Settings 7
◆Speed-limit Settings 8
Personalized Parameter Settings 9
◆Battery Power Bar Settings 9
◆Assistance Level Settings (optional) 9
Assistance Level Option 9
PAS Ratio Settings 10
◆Controller Over-current Cut Settings (optional) 10
◆Power Assistant Sensor Settings (optional) 11
The Direction of PAS Settings 11
The Sensitivity of PAS Settings 11
◆Magnet Quantity Settings 11
◆Speed Sensor (optional) 12
◆Throttle Definition (optional) 12
Throttle Push-assistance Enable/Disable 12
Throttle Level Enable/Disable 12

System Settings (optional) 13
◆Delay Time Settings of Battery Power 13
◆Button Push-Assistance Enable/Disable 13
◆Push-Assistance Speed Settings 13
◆Slowly Start Up Settings 14
◆Power-On Password Settings 14
◆Power-On Password Enable/Disable 14
◆Power-On Password Modify 15
◆Exit Settings 15
Recover Default Settings 15
Quality Assurance and Warranty Scope 16
Connection Layout 16
Operation Cautions 17

Product Name and Model
Intelligent LCD display for E-bike; model: KD51C.
Specifications
●24V/36V/48V Power Supply
●Rated working current: 10mA
●The maximum working current: 30mA
●Off leakage current: <1uA
●The supply controller working current: 50mA
●Working temperature: -20℃~ 60℃
●Storage temperature: -30℃~ 70℃
Appearance and Size
Display appearance and dimension figure (unit: mm)

Function Summary
◆Function Summary
KD51C can provide a lot of functions to fit the users’ needs. The indicating contents
are as follows:
●Smart battery indicator
●Assistance-level indication
●Speed indication (incl. running speed, max speed and average speed)
●Odometer and trip distance
●The push-assistance function
●Trip time indication
●Backlight On/Off
●Error code indication
●USB port
●Motor-output indicator
●Various parameters settings (e.g., wheel size, speed-limit, battery level bar,
assistance level, controller limited current, power-on password, etc.)
●Recover default settings

◆Functional Area Distribution
General Operation
◆Switching the E-bike System On/Off
Briefly press the power button to switch on the E-bike system,
To hold the power button for 2 s again, the E-bike system will be switched off.
When switching off the E-bike system, the leakage current is less than 1 uA.
■When parking the E-bike for more than 10 minutes, the E-bike system switches off
automatically.
◆Display Interface
After switching on the E-bike system, the display will show Speed and Total Distance
by default. Pressing the “i” button will show more riding data as follows: Running
Speed (Km/h)→ Ave. Speed (Km/h) →Max. Speed (Km/h) → Trip Distance (Km) →
Total Distance (Km)→ Trip Time (Min.) .
Display interface cycle

◆Switching Push-assistance Mode On/Off
To activate the push-assistance function, hold the “-” button always. The E-bike’s
drive is activated at a uniform speed of 6 Km/h. And “WALK” shows on the screen.
The push-assistance function is switched off as soon as you release the “-” button on
the operating unit.
Push-assistance Mode
■Push-assistance function may only be used when pushing the E-bike. Danger of injury when
the wheels of the E-bike do not have ground contact while using the push- assistance function.
◆Switching the Lighting On/Off
To switch on the lighting (headlights, taillights and display backlight), briefly press the
“ ” button. In the same way to press the " ”button again, the lighting can be
switched off.
Switching the Lighting On/Off Interface
◆Assistance Level Selection
The level of assistance of the E-bike drive when pedaling can be adjusted via the
display. The assistance level can be changed anytime, even during riding.
The default assistance level ranges from level “0” to level “5”.The output power is zero
on Level “0”. Level “1” is the minimum power. Level “5” is the maximum power.
To increase the assistance level, press the “+” button until the desired assistance level
is displayed; to decrease the assistance level, press the “-” button. The default value is
level “1”.

◆Battery Indicator
Assistance Level “5”
The five battery bars represent the capacity of the battery. Each bar of the battery pack
symbol is equivalent to a capacity of approx. 20%. When the battery is at low voltage, the
battery frame will flash at frequency of 1 HZ to give notice that the battery needs to be
recharged immediately.
◆Motor Power Indicator
The power of the motor can be read via the interface.
◆USB Connection Indicator
Motor Power Indication
External devices connect with the USB port of the display. The USB icon shows in
below picture:
USB Connection Indicator
Low voltage
flash
Battery
Indicator

◆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 in the text indication area.
Here is the detailed message of the error code in Attached list 1.
Error Code Indication
■Make the display repaired when an error code appears. Or else you can not ride the bike.
General Settings
To access the general settings menu, hold both the “+” button and the “-” button for 2 s.
■All the Settings are operated in the case of parking the E-bike.
◆Trip Distance Clearance
TC represents trip distance clearance setting.
To clear the trip distance, press the “+” button or the “-” button until the Y/N is
displayed. Y represents clearing a trip distance and N represents NOT clearing a trip
distance.
To store a changed setting, press the “i” button and then access backlight contrast
settings.
Trip Distance Clearance Settings Interface
◆Backlight Contrast Settings
BL represents backlight contrast settings. Level “1” is the low brightness, Level “2” is
the middle brightness, Level “3” is high brightness. The default level is “1”.
To modify the backlight brightness, press the “+” button or the “-” button to choose the
desired setting item.
To store a changed setting, press the “i” button and then access the unit Conversion
Settings.

◆Unit km/mi Conversion
Backlight Brightness Settings Interface
U represents unit settings, “1” is mile and “2” is kilometer. The default value is “2”.
To convert a unit, press the “+” button or the “-” button to choose the desired setting
item, and then press the “i” button to confirm.
To store a changed setting, press the “i” button and then access trip distance clearance
settings.
Or, hold the “i” button for 2 s and then exit General Settings.
Mile and Kilometer Conversion Settings Interface
General Parameter Settings
To access the general parameter Settings interface, hold both the “+” and the “-”
button for 2 s and then hold both the “-” and the “i” button for 2 s again.
◆Wheel Diameter Settings
Ld represents wheel diameter settings. Electable values include 16, 18, 20, 22, 24,
26, 700C and 28.
To change basic settings, press the “+” or the “-” button to increase or decrease until
the desired value is displayed.
To store a changed setting, press the “i” button. Then access the speed-limit settings
interface. The default value is 26 inch.
Wheel Diameter Settings Interface

◆Speed-limit Settings
LS represents the limit speed settings. When the current speed is faster than the speed
limit, the E-bike system will switch off automatically. Speed limit range is 12Km/h to 40Km/h.
The default value is 25Km/h.
To change basic settings, press the “+” or the “-” button to increase or decrease until
the desired value is displayed.
To store a changed setting and exit General Parameter Settings, hold the “i” button for 2
s.
Limit Speed Settings Interface

Personalized Parameter Settings
Personalized Parameter Settings can match a variety of requirements in use. There are
8 settings items, such as Battery Power Bar Settings, Power Assistant Level Settings, Over-
current Cut Settings, Power Assistant Sensor Settings, Speed Sensor Settings, Throttle
Function Settings, System Settings and Power-on Password Settings.
To access Personalized Parameter Settings items option page, hold both the “+”
and the “-” button for 2 s, then hold both the “+” and the “-” button for 2 s again.
To access the corresponding settings page, press the “+” or the “-” button to increase
or decrease until the desired item is displayed, and then press the “i” button to confirm.
◆Battery Power Bar Settings
Options Selection Interface
VOL represents voltage settings. Each bar represents a voltage value. 5 bars voltage
values must be entered one by one. For example, VOL 1 is the first bar voltage value. The
default value is 31.5V.
To set the battery power bar, press the “+” or the “-” button to increase or decrease
the number. To store a changed setting and access the second bar, press the “i” button.
Likewise,after 5 bars voltage values are entered completely, hold the “i” button to
confirm and then return to the previous menu.
Battery Power Bar Settings
◆Assistance Level Settings (optional)
Assistance Level Option
In assistance level settings, there are 8 modes to select：0-3, 1-3, 0-5, 1-5, 0-7, 1-7, 0-
9, 1-9. The default value is 0-5.
To change the mode of assistance-level, press the “+” or the “-” button to choose the
desired mode, and then press the “i” button to confirm, then access the PAS ratio settings
page automatically.

PAS Ratio Settings
PAS Mode Option Interface
To modify the value of PAS ratio, press the "+" button or "-" button to choose the
desired value, and then press the "i" button to confirm
For example, the range is “45-55 percent” for level “1”, ratio value can be modified, and
the default value is 50 percent.
To store the modified setting, press the “i” button and move to the next PAS ratio settings.
After all PAS ratios input, hold the “i” button for 2 s to confirm and then return to the
previous menu. Please refer to Attached list 2 for PAS ratio default values.
PAS Ratio Interface
◆Controller Over-current Cut Settings (optional)
CUR represents controller over-current cut settings. CUR value can be changed from
7.0A to 25.0A. The default value is 15A.
To change basic settings, press the “+” or the “-” button to increase or decrease the
value of the current.
To store a changed setting, hold the “i” button and then return to the previous menu.
CUR Settings Interface

◆Power Assistant Sensor Settings (optional)
The Direction of PAS Settings
PAS represents power assistant sensor settings. “run-F” means forward direction,
while “run-b” means backward direction. The default value is “run-F”.
To change The Direction of Power Assistant Sensor Settings, press the “+” or the “-”
button to select F or b.
To store a changed setting, press the “i” button and then access settings mode of PAS
sensitivity.
Direction of PAS Sensor Settings
The Sensitivity of PAS Settings
SCN represents the sensitivity of PAS settings. The sensitivity value is “2” to “9”. “2” is
the strongest, “9” is the weakest. The default value is “2”.
To change the sensitivity of PAS settings, press the “+” or the “-” button to select
sensitivity value.
To store a changed setting, press the “i” button and then access magnet disk settings
mode.
The Sensitivity of PAS Settings
◆Magnet Quantity Settings
n represents magnet numbers on the PAS disk. The default value is 6.
To change magnet numbers on the PAS disk, press the “+” or the “-” button to
select the quantity according to the PAS disk.
To store a changed setting, hold the “i” button and then return to the previous menu.
PAS Disk magnet number Settings

◆Speed Sensor (optional)
SPS represents speed sensor settings. The default value is 1
To change speed sensor settings, press the “+” or the “-” button to select the quantity
of magnet head on the wheel spoke (the range is from 1 to 15).
To store a changed setting, hold the “i” button and then return to the previous menu.
◆Throttle Definition (optional)
Speed Sensor Selection
Hnd, it refers to throttle function setting, including 2 sections: HL and HF
HL represents "throttle-6km" setting, i.e. push-assistance by turning the throttle.
HL-N means throttle push-assistance function is disabled. HL-y means throttle push-
assistance function is enabled. The default value is HL-N. means throttle- 6km is disabled
and will enter Throttle-PAS setting. If Hl-y, then will return to the previous menu
Throttle Enable/Disable Interface
Throttle -PAS Enable/Disable
HF represents the "throttle-PAS" setting.
HF-y means throttle speed is limited by current assist level while HF-n means throttle
speed is not limited by current pedal assist level. The default value is "n".
If you choose "y", the maximum speed can only be the highest speed powered by current
pedal assist level when you twist the throttle.
If you choose "n", the maximum speed is not limited by current pedal assist level and you
can override whatever pedal assist level you are at and reach rated maximum speed
when you twist the throttle.
Throttle Level Enable or Disable Interface

System Settings (optional)
◆Delay Time Settings of Battery Power
dLY represents delay time of battery power settings. The default value is 3 s.
To change delay time settings, press the “+” or the “-” button to select delay time 3 s,
6 s, 12 s.
To store a changed setting, press the “i” button and then access the max speed limit.
Delay Time of Battery Power Interface
◆Button Push-assistance Enable/Disable
PUS represents button push-assistance settings. Y represents button push is enabled,
N represents button push is disabled. The default value is Y.
To change button push-assistance settings, press the “+” or the “-” button to choose Y
or N.
To store a changed setting, press the “i” button and then access PAS speed settings.
Interface of Push-assistance
◆Push-assistance Speed Settings
To change PAS speed settings, press the “+” or the “-” button to adjust from 20%
to 35%.
To store a modified setting, press the “i” button and then access slowly start up.
The default value is 25%.
Interface of PAS Speed Settings

◆Slowly Start Up Settings
SSP represents a slow start up. The range is “1-4”, “4” is the slowest. The default
value is “1”.
To slowly start up settings, press the “+” or the “-” button to select the desired value.
To return to the previous menu, hold the “i” button for 2 s.
Interface of Slowly Settings Up
◆Power-on Password Settings
P2, 0000 on the screen means power-on password settings. The default password
is 1212.
To access the power-on password settings, press the “+” or the “-” button to modify
the value and then press the “i” button to confirm digit one by one until the correct 4-digit
password is completed, and then press the “i” button to access power-on password enable
settings interface, otherwise stay on the password input state.
Power-on Password Entering Interface
◆Power-on Password Enable/Disable
To change power-on password enable/disable settings, press the “+” or the “-” button
to select Y or N.
If it is Y, press the “i” button and then access the power-on password modify interface,
otherwise exit the power-on password settings interface. The default value is N.
Y is power-on password enable.
N is power-on password disable.
Power-on Password Disable Interface

◆Power-on Password Modify
When the display shows P3, 0000, to set a new power-on password, press the “+” or
the “-” button to modify the value and then press the “i” button to confirm digit one by one
until the new 4-digit password is completed.
To store the new power-on password, hold the “i” button for 2 s and then exit settings.
When switching the E-bike system on next time, the display will show P1,0000, please
input the new password to power on.
◆Exit Settings
Power-on Password Modify Interface
In the settings state, pressing the “i” button is to confirm the input. Holding the “i”
button is to store the settings, and then exit the current settings. Holding the “-” button is to
cancel the operating but not storing settings data, and then return to the previous menu.
■If there are not any operations in one minute, the display will exit the settings state.
Recover Default Settings
dEF represents recovery default settings. The default value is N.
To access and recover default settings, hold both the “+” and the “i” button for 2 s.
Press the “+” or the “-” button to choose Y or N again. N means that you do not
recover default settings. Y means that it recovers default settings.
When it is Y, hold the “i” button for 2 s to recover default settings; the display shows
DEF-00 at the same time,and then return to general display state.
Recover Default Settings Interface

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 items 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) Beyond warranty period.
6) The fault or damage of the display is caused by force majeure. (e.g. fire,
earthquake, etc.).
Connection Layout
Connector line sequence
SM Connector Waterproof connector mating connector
Line sequence table
Line
Color
Function
1
Red（VCC）
+
2
Blue(K)
Lock
3
Black(GND)
-
4
Green(RX)
RX
5
Yellow(TX)
TX
■Some display cables use the water-proof connector, users can not see the inside color.

Operation Cautions
Be careful of safe use. Don’t attempt to release the connector when the battery is on
power.
●Try to avoid hitting.
●Do not modify system parameters to avoid parameters disorder.
●Make the display repaired when an error code appears.
Attached list 1：Error code definition
Error Code
Definition
21
Current Abnormality
22
Throttle Abnormality
23
Motor Abnormality
24
Motor Hall Signal Abnormality
25
Brake Abnormality
30
Communication Abnormality
Attached list 2：PAS level ratio defaults table
Level
Level selection
1
2
3
4
5
6
7
8
9
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%