Xiaomi Mi Electric Scooter M365 Operating instructions

Table of contents
Table of contents
Warnings 2
Introduction 3
General view 4
Basic specifications 5
Pinout 6
Installation 7
Xiaomi M365 - wiring diagram 7
Xiaomi M365PRO - wiring diagram 8
Installation process video tutorials 9
Setting up the battery 10
Description of parameters 11
Default parameter values 14
Troubleshooting 15
Warranty and technical support 16
1

Warnings
Warnings
WARNING!
Lithium-ion batteries are very dangerous! Improper use of this equipment may cause
a fire.
WARNING!
Use of this equipment requires at least basic knowledge in electronics and electrical
engineering.
WARNING!
When installing this equipment, read and follow the manufacturer's instructions
exactly.
2

Introduction
Introduction
Repair BMS is designed to be installed inside a Xiaomi Mijia M365 / M365PRO electric scooter
battery instead of an original BMS. This is required when an original BMS fails, or when tuning the
battery by replacing all cells with more capacious ones. It is also possible to use this BMS for any
self-assembled 10s battery pack.
A battery equipped with a repair BMS is recognized by the Xiaomi Mijia M365 / M365PRO
electric scooters as standard, so all the original functionality is preserved. In addition, it becomes
possible to flexibly configure many parameters, for example, capacity, discharge curve, serial
number, maximum current, and many other parameters.
3

General view
General view
Activity and error
indicator
Flashes every half second in normal operation.
In case of an error, displays its code.
For more information on error codes, see the “Troubleshooting” section.
Temperature sensors
Information from these sensors is displayed in the smartphone application. If the
sensors detect an excess of the permissible temperature, the BMS temporarily
disables charging and discharging the battery.
Thermal fuse
Irreversibly melts at a critical temperature rise of the battery, completely turning
off the BMS power and, accordingly, the charge and discharge of the battery.
Current fuses
Irreversibly burn out at a critical overcurrent if the software protection did not
work.
4

Basic specifications
Basic specifications
Supported battery types
Li-ion, Li-pol
Supported battery configurations
10s only
Maximum battery capacity, mA*h
32000
Maximum continuous discharge current, A
30
Maximum continuous charge current, A
2
Effective cells balancing current, mA
1.4
5

Pinout
Pinout
Battery pack - negative
lead
Connects to the negative lead of the battery pack
Battery pack - positive
lead
Connects to the positive lead of the battery pack
Balancing cable
Connects to each parallel of the battery pack
Charging connector
Connects to the charge port of the scooter
Discharging connector
Connects to the ESC
Rear light
Connects to the rear light of the scooter
Data
Connects to the ESC
6

Installation
Installation
Xiaomi M365 - wiring diagram
WARNING!
Follow the wiring sequence, otherwise the BMS may irreparably fail, with a loss of
warranty.
1. Connect the black power wire of the BMS to the negative lead of the battery pack.
2. Connect the red power wire of the BMS to the positive lead of the battery pack.
3. Connect the balancing wires in order, starting with B0 and finishing with B10.
4. Install temperature sensors and thermal fuse using a thermal compound or neutral sealant with thermal
grease.
5. Solder the connector that comes with the BMS to the rear light wire.
6. Connect the battery to the scooter.
7. To start the BMS for the first time, connect the charger to the scooter. In case of a successful start, the
indicator LED will blink on the board.
7

Installation
Xiaomi M365PRO - wiring diagram
WARNING!
The cable does not come out of the board in the most convenient way, and when
connecting the balancing wires, you have to cross them. The thing is that initially BMS was
designed even before the PRO version of the scooter appeared on sale, after which the form
of the board was only slightly changed to maintain compatibility.
WARNING!
Follow the wiring sequence, otherwise the BMS may irreparably fail, with a loss of
warranty.
1. Connect the black power wire of the BMS and B0 balancing wire.
2. Connect the balancing wires in order, starting with B1 and finishing with B9.
3. Connect the red power wire of the BMS and B10 balancing wire.
4. Install temperature sensors and thermal fuse using a thermal compound or neutral sealant with thermal
grease.
5. Solder the connector that comes with the BMS to the rear light wire.
6. Connect the battery to the scooter.
7. To start the BMS for the first time, connect the charger to the scooter. In case of a successful start, the
indicator LED will blink on the board.
8

Installation
Installation process video tutorials
Xiaomi M365 BMS replacement
Xiaomi M365PRO BMS replacement
9

Setting up the battery
Setting up the battery
The repair BMS provides the ability to flexibly configure many parameters. The default values can be
left unchanged when the BMS is used just to replace the faulty original Xiaomi M365 board. In the case of the
PRO version of the scooter, you must additionally configure the battery capacity. And if you change cells to
new ones or even assemble your own battery pack, you need to configure a number of parameters to operate
with the new cells.
Please, use the “M365 BMS Tool” application to configure your battery:
Download for Android
Download for iPhone
10

Setting up the battery
Description of parameters
Parameter
Description
Battery serial
This parameter affects only the battery serial number displayed in
applications. You can enter your name there or the name of your repair
shop.
Battery capacity
Very important parameter, it must be set to the correct value, otherwise,
wrong charge level calculation during charge and discharge is possible.
Battery date of production
This parameter affects only the battery production date displayed in
applications.
Discharge curve
Sets the correlation between the voltage of the most discharged parallel and
the charge level, in percent, at 11 points. For example, by default, 0% is
3100mV, 10% is 3200mV, ..., 90% is 4000mV, 100% is 4100mV. Using this
setting, you can carefully adjust the uniformity of the charge level scale to the
non-linear characteristic of the battery cells you use.
Charge overcurrent
The maximum continuous charge current, exceeding which during the time
determined by the “Charge overcurrent delay” parameter, charging will be
disabled for the time determined by the “Charge overcurrent cooldown”
parameter.
Charge overcurrent delay
The time after which the protection against exceeding the charge current is
activated.
Charge overcurrent cooldown
The time during which charging will be disabled after the protection against
exceeding the charge current is activated.
Discharge overcurrent
The maximum continuous discharge current, exceeding which during the
time determined by the “Discharge overcurrent delay” parameter,
discharging will be disabled for the time determined by the “Discharge
overcurrent cooldown” parameter.
Discharge overcurrent delay
The time after which the protection against exceeding the discharge current
is activated.
Discharge overcurrent
cooldown
The time during which discharging will be disabled after the protection
against exceeding the discharge current is activated.
Short circuit current
The maximum continuous discharge current, exceeding which during the
time determined by the “Short circuit delay” parameter, discharging will be
disabled for the time determined by the “Short circuit cooldown” parameter.
Short circuit delay
The time after which the protection against short circuit is activated.
Short circuit cooldown
The time during which discharging will be disabled after the protection
against short circuit is activated.
(continued on the next page)
11

Setting up the battery
Description of parameters(continuation)
Parameter
Description
Cell overvoltage
Voltage above which at least one parallel is exceeded for a time determined
by the “Cell overvoltage delay” parameter, charging is disabled until the
voltage drops to the value
[Cell overvoltage - Cell overvoltage hysteresis].
Cell overvoltage delay
Time after which the overvoltage protection of the parallel is activated.
Cell overvoltage hysteresis
Hysteresis, which is responsible for how much the parallel voltage should fall
after the overvoltage protection is activated, so that the charge is enabled.
Cell undervoltage
Voltage, at which the voltage of at least one parallel is dropped for a time
determined by the “Cell undervoltage delay” parameter, the discharge is
disabled until the voltage rises to [Cell undervoltage + Cell undervoltage
hysteresis].
Cell undervoltage delay
Time after which protection against undervoltage of the parallel is activated.
Cell undervoltage hysteresis
Hysteresis, which is responsible for how much the parallel voltage should
increase after the protection against undervoltage is triggered, so that the
discharge is enabled.
Balancing mode
Three balancing options:
Always - always balance cells, except when their voltage is lower than the
value defined by the “Lowest voltage to balance” parameter.
Charge & Overvoltage - balance cells during charging or when exceeding the
maximum voltage in at least one cell.
Never - never balance cells.
BMS shutdown undervoltage
The voltage, when the voltage drops to at least one parallel for 30 seconds,
the BMS turns off completely, stopping consuming battery current. This is
necessary in case the scooter is left discharged for a long period so that
BMS does not overdischarge the battery pack by its own current
consumption.
Lowest voltage to balance
The minimum parallel voltage at which it will be balanced.
Cells disbalance threshold
How much should the parallel voltage exceed the voltage of the most
discharged parallel in order for balancing to begin.
Recuperation disable cell
voltage
If at least one parallel the voltage is higher than this value, a signal is sent to
the controller to disable the recuperation.
(continued on the next page)
12

Setting up the battery
Description of parameters(continuation)
Parameter
Description
Critical temperature
If the temperature of at least one temperature sensor is above this value
during the time determined by the “Critical temperature delay” parameter,
then discharge and charge will be disabled until the temperature of each
temperature sensor falls below the [Critical temperature - Critical
temperature hysteresis] value.
Critical temperature delay
Time after which the protection against temperature exceeding activates.
Critical temperature hysteresis
Hysteresis, which is responsible for how much the temperature should drop
after the protection against temperature exceeding is activated, so that the
discharge and charge are enabled again.
13

Setting up the battery
Default parameter values
Parameter
Default value
Battery serial
“embedden.com”
Battery capacity, mAh
7800
Battery date of production
19.07.2019
Discharge curve, mV
3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100
Charge overcurrent, A
2
Charge overcurrent delay, ms
2000
Charge overcurrent cooldown, s
10
Discharge overcurrent, A
33
Discharge overcurrent delay, ms
1280
Discharge overcurrent cooldown, s
10
Short circuit current, A
111
Short circuit delay, us
70
Short circuit cooldown, s
10
Cell overvoltage, mV
4200
Cell overvoltage delay, s
4
Cell overvoltage hysteresis, mV
100
Cell undervoltage, mV
3000
Cell undervoltage delay, s
4
Cell undervoltage hysteresis, mV
100
Balancing mode
Charge&Overvoltage
BMS shutdown undervoltage, mV
2600
Lowest voltage to balance, mV
3400
Cells disbalance threshold, mV
30
Recuperation disable cell voltage, mV
4150
Critical temperature, °C
60
Critical temperature delay, s
5
Critical temperature hysteresis, °C
10
14

Troubleshooting
Troubleshooting
Trouble:
The battery does not work, the LED on the BMS board does not blink
Solution:
1. Connect the charger: normally this starts the correctly connected BMS.
2. Check the connection is correct, in case of an error - reconnect correctly.
3. Make sure that all the parallels of the battery pack are OK: their voltage should be in the range of about
2.5 to 4.2 volts.
Trouble:
BMS starts up, but after about 30 seconds it shuts down itself.
Solution:
Check if the voltage drops at least one parallel lower than the “BMS shutdown undervoltage”
parameter(it’s default value is 2.6V). If yes, then after starting BMS, leave the charger connected so that the
problematic parallel is charged.
Trouble:
BMS flashes LED, but the scooter does not turn on.
Solution:
1. Check battery output voltage. If it is in the range of about 30 to 42 volts, it means that the BMS board
and the battery pack are OK, and the problem should be looked for in the scooter controller.
2. If the voltage at the output of the scooter is below 30 volts, pay attention at the blinking LED, it signals
errors that disable the discharge of the battery:
a) a short flash once per second means at least one of the parallels of the battery is discharged
below the level of the “Cell undervoltage” parameter. It is important to understand why this
happened. If the battery is completely discharged, and all the cells are evenly discharged to a
low level - this is the normal mode of operation, there is nothing to worry about, you just need to
connect the charger and charge the battery. But if only one parallel dropped down - this is a
cause to look for broken contacts or a faulty cell.
b) continuous light - means the protection against overcurrent or short circuit protection has
activated. In this case, you just have to wait 10-20 seconds.
c) a long flash once a second - it means that the protection against temperature rise has
activated. In this case, wait until the temperature drops.
d) a short flash every half a second - this is normal mode, there are no errors disabling the
discharge of the battery. If the LED blinks like this, but there is no voltage at the BMS output, it
means the board malfunction, please contact the technical support.
15

Warranty and technical support
Warranty and technical support
I do not accept returns and no longer provide a warranty because there are more
and more cases where unqualified customers burn the BMS due to incorrect connection,
and then require a warranty exchange. At the same time, if you are a skilled guy, be free
to order and install the BMS - it's quality is proved by years and hundreds of installations. I
just protect myself from unqualified customers by voiding the warranty.
If you did not find the answer to your question after reading this manual, please, feel free to ask your
questions in the special telegram group:
Xiaomi M365/PRO/1S custom electronics
by Denis Yurev
16