This document provides a summary of the key features and specifications of a high voltage stackable battery management system (BMS). The BMS uses a modular design with a master unit that can be stacked with up to 5 slave units to monitor and control up to 144 cells. It measures cell voltages and temperatures, balances cells, monitors battery health, controls charging and protects the battery from faults. The BMS communicates via CAN and supports logging battery data for analysis.

1. BMS S05
High voltage stackable BMS system
Datasheet

2. Features
- Stackable design with one master and more slaves unit.
o Each unit controls 24 cells (divided into two 12 cells groups)
- High precision cell voltage measurement with 1.2 mV maximum total error
- External high precision digitally isolated shunt for current measurement
- Passive cell balancing (balancing current 0.5 A). Fully programmable balancing settings. Supports initial
pack balancing (requires charger with current control).
- Controls external charger
o Charger disconnect relay
o Charger current control (0-10 V or PWM) on selected chargers
- Battery protections:
o Under voltage
o Overvoltage (during charging and regeneration in discharge mode)
o Overcurrent
o Low and high temperature
- Battery monitoring functions
o Calculates SOC
o Measures cell internal resistance
o Reported cell voltages are open cell voltages (compensated for internal resistance).
o Calculates SOH (state of health). This is possible if battery fully discharged durring use.
o Measures total charge in battery life time
o Counts:
Number of cycles
Number of deep discharge events (SOC < 10%)
- Calculates maximum discharge and charge limits according to actual battery state
- BMS protections
o Broken string or cell connection
o Broken connection between stacked BMS modules
o Error on shunt (no communication, wrong value)
o Problem with internal BMS balancing resistors
o Each cell connection has internal fuse and overvoltage protection
o Over temperature protection for BMS. It will reduce charging current and number of active
balancing resistors in case of BMS overheating
o Watchdog for SW monitoring
o HW watchdog for monitoring balancing resistors and all relay outputs
- BMS indicators
o LED diode for each cell shows balancing function
o LED diode on each BMS shows communication from master to each of slave modules in BMS
stack
o Seven segment display
Shows current mode (Discharge, charge, final balancing error)
Shows current SOC, cell voltage difference in final balancing or error code
- Logging functions
o Fully customizable which values are logged
o Data is stored in internal FLASH
o Download with PC software, support for graphs and export to CSV text files.
- Auto installation
o BMS automatically detect connected cells at power on and verifies if total number of cells is equal
as configured

3. o In each group of 12 cells can be random connected (as long total voltage in each group is always
above 11 V).
- Hardware functions
o Integrated control for main battery relay and pre-charge relay
o Integrated high voltage isolation monitor
o Integrated high voltage interlock
o Analogue outputs or PWM for SOC, maximum charge and discharge current
o One temperature sensor for each group of 12 cells
o Control for external battery fan
o BMS aluminum back plate used for cooling
o Additional heat sink can be mounted on BMS back plate
- Communication interfaces:
o CAN interface (Canopen standard).
o Secondary CAN acts as OBD II master. Standard vehicle displays/gauges can be used. Support for
OBD scan applications (example Torque pro on tablets)
o RS232
Isolation
Cell connections with cell functionality (voltage, temperature measurement, balancing) are isolated from rest of
circuit. Isolation voltage 1000 Vdc.
DC/DC converter, isolation monitor and pre-charge detect circuit are isolated from rest of circuit. Isolation voltage
1000 Vdc.
Logic functions (communication, inputs, and outputs) have 60 V DC isolation from backplate.
BMS back plate is electrical isolated from rest of circuit. (1000 or 6 V DC).
Isolation monitor requires that BMS heatsink. Isolation monitors has internal 1 Mohm resistors from HV- and HV+
to logic GND.

4. Picture Isolation between BMS subsystems

5. Stacking of BMS
BMS can be stacked to support high voltage applications. Each module supports 24 cells. On one master module can
be connected up to 5 slave modules. Such configuration supports up to 144 cells in the series.
Picture: Stacking and current sensor
Master unit can be used as slave if connectors X3, X5, X6 are not connected. This is not price optimal, but allows
stacking of same battery blocks equipped with master modules.
Standard M8 cables are used for stacking. Each module is delivered with stacking cable so no additional cables are
needed. Standard length of stacking cable is 0.5 m, other length on request.

6. Current sensor
External current sensor /shunt can be connected to master module. It is fully isolated and powered from master
module.
Specification for current sensor
- maximum current 500 A
- accuracy 0.5 % (each sensor is calibrated)
- Offset error < 100 mA
- shunt resistance 0.1 mOhm
- digital isolated communication with BMS
Current sensor is supplied with 0.5 m long cable to BMS.

7. Connectors master module
X1
Current sensor/lower stack
M8 4 pin, codding A, female. Signals isolation from chasis 60 V.
1 GND
2 Com- BMS communication
3 Com+ BMS communication
4 5 V Used for power current sensor. Max 50 mA
Shield Connected to BMS heat sink with 1 MOhm

8. X2
Upper stack M8 cable
M8 4 pin, codding A, female. Signals isolation from chasis 60 V.
1
2 Com- BMS communication
3 Com+ BMS communication
4
Shield Connected to BMS heat sink with 1 MOhm
X3
Extra communication
Molex Mini-Fit 8 pin. Signals isolation from chasis 60 V.
1 GND
2 RS232 Tx
3 Rs232 Rx
4 Boot Used for SW upgrade. Connect to GND for upgrade
5 +Power For powering OBD II interfaces. Max 100 mA. Same voltage as on Power
source inputs on main connector.
6 GND
7 CAN2H Second CAN interface. Used as OBD II master
8 CAN2L

9. X4a, X4b
Cell connections
Molex Mini-Fit 16 pin. Isolation from chassis 800 VDC.
1 Temp. return
2 Temp. sensor 1 NTC 10 k B25/50 value of 3380K
3 Temp. sensor 2 NTC 10 k
4 Cell 1-
5 Cell 1+
6 Cell 2+
7 Cell 3+
8 Cell 4+
9 Cell 5+
10 Cell 6+
11 Cell 7+
12 Cell 8+
13 Cell 9+
14 Cell 10+
15 Cell 11+
16 Cell 12+

10. X5
System connector
Molex Mini-Fit 24 pin
Pin Name Full name Rating Comment
POWER SECTION
13 Pa Always On Power Source 8-30V (to CPU as
Analog IN)
1 Pd Ready Power Source (Discharge mode) Can be connected to
output of internal 12
DC/DC
8-30V (to CPU as
Analog IN)
2 Pc Charge Power Source Connected to
charger auxiliary
12V
8-30V (to CPU as
Analog IN)
14 GND GND
18 I01 Multi purpose input or low side out Max. 30V (to CPU as
Analog IN) . Pull
down 10k. Output can
be also PWM. Max
current 200mA.
Suppressor 33 V
placed across the line
(ZXMS6004)
19 I02 Multi purpose input or low side out See IO1. Different
timer for PWM.
Analog input range 0-5
V
OUTPUTS
11 O2 Main DC contactor positive
OUT2
Switch to GND
max 4 A
23 O3 Main DC contactor negative
OUT3
Switch to GND
max 4A
8 O4 Pre-charge contactor
OUT4
Switch to GND
max 1A
9 O5 Charge Allowed
OUT5
Switch to GND
max 1A
Signal that battery can
absorb energy. Used to
prevent controller
regeneration
10 O6 Charger Enable Switch to GND Controls charger relay

11. OUT6 max 1A
20 O7 OUT7 Switch to GND
max 1A
21 O8 OUT8 Switch to GND
max 1A
22 O9 PWM output
OUT9
To CPU timer
max 200 mA
Open collector out.
Internal pull up (4,7k)
with diode to logic
power (Diodes
ZXMS6004FF).
Active low
Suppressor 33 V
placed across the line
ANALOGUE OUTPUTS
15 As SOC state analogue out linear 0-5V,
max 20 mA
4 Ac Max. Charger current DAC/PWM linear 0-5V or PWM
mode, max 20 mA
3 Ad Max. Discharge current DAC/PWM linear 0-5V or PWM
mode, max 20 mA
16 GND GND
CAN
6 Ch CAN1H
5 Cl CAN1L
17 GNDc GND (optional isolated)
INTERLOCK
7 Lck HV Interlock + Internal hardware
voltage comparator.
Open all relays on
fault.
10 mA current source
from logic power.
Nominal voltage 2.5
V. Nominal external
resistor 220 Ohms to
GND
Connector pinout
1 2 3 4 5 6 7 8 9 10 11 12
Pd Pc Ad Ac Cl Ch Lck O4 O5 O6 O2 GND
Pa GND As GND GNDc IO1 IO2 O7 O8 O9 O3 GND
13 14 15 16 17 18 19 20 21 22 23 24

12. X6
Molex Mini-Fit 5 pin single row
High voltage connector
1 HV - Direct connection to stack -
.
Used in isolation fault
circuit.
Internally connected with 1
MOhm to BMS heat sink
2
3 Pre-charge sense Measures difference
between HV+ and this pin to
detect when pre-charging is
finished
4
5 HV+ Direct connection to stack
+.
Used in isolation fault
circuit.
Internally connected with 1
MOhm to BMS heat sink
X7
Discharge relay
Molex Mini-Fit 3 pin single rowi
1 Discharge Enable relay - See description of Discharge
Enable +
2
3 Discharge Enable relay +
OUT1
Internal electronic DC
relay 400 V 2A. 1kV
isolation from rest of
circuit. Suppressor 500 V
across contacts
If discharge is allowed
is activated before/after
precharge phase.

13. LED diodes
On slave module (per 12 cell block):
1x yellow – blink with 1 Hz on communication with balancer IC
8x green – connected with balancing resistor
On master PCB:
- Green and Red for Canopen functionality
- Blue – Bluetooth
- Yellow – CAN2
- Yellow – RS232

14. Connectors slave module
Slave module has only cells (X4a, X4b) and stack (X1, X2) connectors.
Dimensions
Dimensions with optional 40 mm high heat sink.