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Getting started with the battery management system (BMS) evaluation board
Introduction
The
STEVAL-BMS114
battery management system (BMS) evaluation board can handle from 1 to 31 Li-ion battery nodes. Each
battery node manages from 4 to 14 battery cells, for a voltage range between 48 and 800 V.
The board is based on the L99BM114. The main activity of the L99BM114 is monitoring cells and battery node status through
stack voltage, cell voltage, and temperature measurements and coulomb counting. Measurement and diagnostic tasks can be
executed either on demand or periodically at a programmable cycle interval. Measurement data are available for an external
microcontroller to perform charge balancing and to compute the state of charge (SOC) and the state of health (SOH).
The
STEVAL-BMS114
can measure 5 values of temperature through 5 GPIOs (which can be configured as analog inputs to
connect NTCs).
The
STEVAL-BMS114
provides an elaborate monitoring network to sense the voltage, current, and temperature of each cell.
ST offers BMS evaluation boards (STEVAL-BMS114, STEVAL-BMS114TX) to meet customers' needs and help designers build
different types of BMS chain topologies fit for any end-user application.
The STEVAL-BMS114 provides an elaborate monitoring network to sense the voltage, current, and temperature of each cell.
Notice:
For dedicated assistance, submit a request through our online support portal at www.st.com/support.
UM3423 - Rev 1 - January 2025
For further information, contact your local STMicroelectronics sales office.
Figure 1.
STEVAL-BMS114 evaluation board
UM3423
User manual
based on the L99BM114
www.st.com
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Summary of Contents for ST STEVAL-BMS114
- Page 1 ST offers BMS evaluation boards (STEVAL-BMS114, STEVAL-BMS114TX) to meet customers' needs and help designers build different types of BMS chain topologies fit for any end-user application. The STEVAL-BMS114 provides an elaborate monitoring network to sense the voltage, current, and temperature of each cell. Figure 1.
- Page 2 Compact size: 100 x 76 mm 1.1.2 Main components 1. ISOL port to connect the board to another STEVAL-BMS114 in a daisy chain 2. ISOH port to connect the board to the STEVAL-BMS1T 3. L99BM114 multicell battery monitoring and balancing IC 4.
- Page 3 UM3423 BMS evaluation board overview Table 1. STEVAL-BMS114 connector details Name Description Type Isolated serial communication port: 1. VBUS ISOH 2. ISOHm USB Type A connector 3. ISOHp 4. FaultH Isolated serial communication port: 1. VBUS ISOL 2. ISOLm USB Type A connector 3.
- Page 4 UM3423 BMS evaluation board overview Embedded devices 1.2.1 L99BM114 The L99BM114 is intended for operation in systems using lithium battery packs. The IC embeds all the features needed to perform battery management. A single device can monitor from 4 up to 14 cells. The device can be supplied with the same battery it monitors, and its main activity consists of monitoring cells and battery pack status through stack voltage measurement, cell voltage measurement, temperature measurement, and coulomb counting.
- Page 5 The power supply range is from 9.6 V to a maximum of 64 V. 1.3.1 Linear regulators The STEVAL-BMS114 features several linear voltage regulators, which are switched on according to a specific sequence at power-up (see L99BM114 datasheet). VREG This linear regulator exploits an external MOS to decrease the power dissipation inside the L99BM114.
- Page 6 BMS topologies BMS topologies The STEVAL-BMS114 can work in two different daisy chain topologies: single access and dual access ring. Single access configuration In a single access daisy chain configuration, a series of BMS is connected to an MCU board through a single transceiver connected to the STEVAL-BMS114 isolated ISOL port.
- Page 7 UM3423 BMS topologies Dual access ring configuration A dual access ring configuration is implemented by adding another transceiver that makes the communication bidirectional. The secondary transceiver is used as a backup in case the primary transceiver fails. Data moves in opposite directions around the rings, and each ring remains independent of the other unless the primary ring fails.
- Page 8 UM3423 Cell current measurement Cell current measurement The current flowing into the external shunt resistance RSENSE is measured through a differential amplifier stage (connected between ISENSEP/ISENSEM pins) feeding a 18-bit ADC. The current conversion chain can be enabled through the CoulombCounter_en bit and runs in background to perform the Coulomb Counting Routine.
- Page 9 UM3423 Fault condition in daisy chains Fault condition in daisy chains Figure 6. Fault LED on the STEVAL-BMS1T The fault LED on the STEVAL-BMS1T is related to the state of all the BMS nodes in the daisy chain. If an undervoltage, overvoltage, overcurrent, or overtemperature occurs on any cell of a BMS, a fault condition is detected.
- Page 10 UM3423 Cell balancing Cell balancing In the L99BM114, the Sx and Bx_x-1 pins are used to balance the charge of the cells by discharging the ones with a higher SOC. Balancing can be performed either with external resistors or internal MOSFETs. Cell balance drivers are powered by VBAT stack voltage.
- Page 11 Schematic diagram Figure 8. STEVAL-BMS114 circuit schematic VBATT VBAT_UP STL8N10LF3 VBAT_CELL VBAT_CELL MPZ2012S102ATD25 RMREG 47nF N.M. 4.7uF VBAT_CELL 2.2uF 100nF 100pF 100nF 100K GND_EXT 100nF N.M. L99BM114-TR N.M. VREG VBAT VREG VREG CELL14 VCOM VTREF VCOM VCOM ISENSEM ISENSEP GND_EXT...
- Page 12 UM3423 Bill of materials Bill of materials Table 2. STEVAL-BMS114 bill of materials Item Q.ty Ref. Part / Value Description Manufacturer Order code C1, C8, C15, C19, C21, C29, C31, C33, C40, 47nF 0603 - 50V - X7R Class II...
- Page 13 UM3423 Bill of materials Item Q.ty Ref. Part / Value Description Manufacturer Order code FB1, FB2, FB3, FB4, FB5, FB6, Ferrite Beads Multi-Layer FB7, FB8, 1K@100MHz Power 1KOhm 25% 100MHz MPZ2012S102ATD25 FB9, FB10, 1.5A 0.15Ohm DCR 0805 FB11, FB12, FB13, FB14, FB15, FB16 USB 2.0 Type A, Receptacle, ISOH, ISOL...
- Page 14 UM3423 Bill of materials Item Q.ty Ref. Part / Value Description Manufacturer Order code 0603 - ±1% - 0.1W NTCG163JH103HTDS 3.9k 0603 - ±1% - 0.1W Panasonic ERJ3EKF3901V 0603 - ±1% - 0.2W Panasonic ERJP03F2001V R53, R54, 1.5K 2010 - ±1% - 2W TE Connectivity 35021K5FT R55, R57, R58 N.M.
- Page 15 UM3423 Board versions Board versions Table 3. STEVAL-BMS114 versions Finished good Schematic diagrams Bill of materials STV$BMS114A STV$BMS114A schematic diagrams STV$BMS114A bill of materials 1. This code identifies the STEVAL-BMS114 evaluation board first version. UM3423 - Rev 1 page 15/21...
- Page 16 UM3423 Regulatory compliance information Regulatory compliance information Notice for US Federal Communication Commission (FCC) For evaluation only; not FCC approved for resale FCC NOTICE - This kit is designed to allow: (1) Product developers to evaluate electronic components, circuitry, or software associated with the kit to determine whether to incorporate such items in a finished product and (2) Software developers to write software applications for use with the end product.
- Page 17 UM3423 Revision history Table 4. Document revision history Date Version Changes 10-Jan-2025 Initial release. UM3423 - Rev 1 page 17/21...
- Page 18 STEVAL-BMS114 overview ........
- Page 19 STEVAL-BMS114 main components ........
- Page 20 STEVAL-BMS114 connector details ........
- Page 21 ST’s terms and conditions of sale in place at the time of order acknowledgment. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of purchasers’...
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