# BMS ## Description ESP32-C3 Smart 3S Li-ion/LiPo Battery Management System with Per-Cell Monitoring and Protection ## Project Details - **Owner:** 21ecb34 - **Created:** 11/6/2025 - **Last Updated:** 11/19/2025 - **Visibility:** Public - **System Architecture:** ESP32-C3 SuperMini microcontroller with I2C-connected ADS1115 analog-to-digital converter, cell voltage taps routed through a BMS AFE/Protector IC for balancing and protection, passive cell balancing, current shunt/Sense Amp for pack current, MOSFETs for charge/discharge control, NTC temperature sensing, and all cell/pack interconnects indicated. - **Power Requirements:** Battery - **Description:** Smart 3S Li-ion/LiPo Battery Management System with ESP32-C3 and ADS1115; includes voltage, current, and temperature sensing, passive balancing, and WiFi communication. - **License:** https://www.gnu.org/licenses/gpl-3.0.html - **Connectivity:** WiFi - **Domain:** Energy ## Key Components ### J1 — [XHP-4](https://www.flux.ai/adrian95/xhp-4.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: JST Sales America Inc. - Role: Connector - Manufacturer Part Number: XHP-4 - Role Details: 3-cell battery tap connector - Datasheet URL: https://www.jst-mfg.com/product/pdf/eng/eXH.pdf - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J2 — [2-Position Screw Terminal](https://www.flux.ai/corynrobinson/2-position-screw-terminal.md) - Part Type: Connector - Role: Connector - Manufacturer Name: Würth Elektrik - Datasheet URL: https://www.we-online.com/katalog/datasheet/691137710002.pdf - Manufacturer Part Number: 691137710002 - Role Details: Main high-current battery connector **Pins:** - P1 [pin 1] - P2 [pin 2] ### J3 — [Pin Header 01x04 2.54mm Vertical](https://www.flux.ai/adrian95/pin-header-01x04-254mm-vertical.md) - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: I2C header (SDA, SCL, VCC, GND) - Role: Connector - Part Type: Connector **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] ### J5 — [282836-3](https://www.flux.ai/jecstronic/282836-3.md) - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1308389_EUROSTYLE_TERMINAL_BLOCKS&DocType=CS&DocLang=English - Manufacturer Part Number: 282836-3 - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Connector - Manufacturer Name: TE Connectivity AMP Connectors **Pins:** - PIN1 [pin 1] - PIN2 [pin 2] - PIN3 [pin 3] ### J6 — [282836-3](https://www.flux.ai/jecstronic/282836-3.md) - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1308389_EUROSTYLE_TERMINAL_BLOCKS&DocType=CS&DocLang=English - Manufacturer Part Number: 282836-3 - Manufacturer Name: TE Connectivity AMP Connectors **Pins:** - PIN1 [pin 1] - PIN2 [pin 2] - PIN3 [pin 3] ### K1 — [Relay-12VDC-SL-C](https://www.flux.ai/deadzerok/relay-12vdc-sl-c.md) - Part Type: Relay - Manufacturer Part Number: SRD-12VDC-SL-C - Datasheet URL: https://datasheet.lcsc.com/lcsc/2304140030_Ningbo-Songle-Relay-SRD-12VDC-SL-C_C30431.pdf - Manufacturer Name: Ningbo Songle Relay - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - Coil-1 [pin COIL1] - Coil-2 [pin COIL2] - Com-3 [pin COM] - NC [pin NC] - NO [pin NO] ### K2 — [Relay-12VDC-SL-C](https://www.flux.ai/deadzerok/relay-12vdc-sl-c.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Ningbo Songle Relay - Manufacturer Part Number: SRD-12VDC-SL-C - Datasheet URL: https://datasheet.lcsc.com/lcsc/2304140030_Ningbo-Songle-Relay-SRD-12VDC-SL-C_C30431.pdf - Part Type: Relay **Pins:** - Coil-1 [pin COIL1] - Coil-2 [pin COIL2] - Com-3 [pin COM] - NC [pin NC] - NO [pin NO] ### Q1 — [AO3400A](https://www.flux.ai/lcsc/ao3400a.md) - LCSC Part Number: C347475 - Product Info Url: https://lcsc.com/product-detail/Others_Youtai-Semiconductor-Co-Ltd-AO3400A-5-8A_C347475.html - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2410010301_UMW-Youtai-Semiconductor-Co---Ltd--AO3400A_C347475.pdf - Role: Switching - Operating Temperature: -55 ~ +150℃ - JLCPCB Part Class: Extended Part - Transistor Type: N-channel MOSFET - Continuous Drain Current: 5.7A - Power: 1.4W - Manufacturer Part Number: AO3400A - Part Type: MOSFETs - Role Details: Charge and discharge MOSFETs controlled by BQ76920 CHG/DSG - Manufacturer Name: UMW(友台半导体) - Package or Case Code: SOT-23-3_L2.9-W1.3-P1.90-LS2.4-BR - Drain to Source Voltage: 30V **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q2 — [AO3400A](https://www.flux.ai/lcsc/ao3400a.md) - Continuous Drain Current: 5.7A - Power: 1.4W - Manufacturer Part Number: AO3400A - LCSC Part Number: C347475 - Product Info Url: https://lcsc.com/product-detail/Others_Youtai-Semiconductor-Co-Ltd-AO3400A-5-8A_C347475.html - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2410010301_UMW-Youtai-Semiconductor-Co---Ltd--AO3400A_C347475.pdf - Operating Temperature: -55 ~ +150℃ - JLCPCB Part Class: Extended Part - Role: Switching - Transistor Type: N-channel MOSFET - Manufacturer Name: UMW(友台半导体) - Role Details: Charge and discharge MOSFETs controlled by BQ76920 CHG/DSG - Package or Case Code: SOT-23-3_L2.9-W1.3-P1.90-LS2.4-BR - Drain to Source Voltage: 30V - Part Type: MOSFETs **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### U1 — [ESP32-C3 SuperMini](https://www.flux.ai/jecstronic/esp32-c3-supermini.md) - Manufacturer Name: Texas Instruments Inc. - Part Type: Module - Datasheet URL: https://www.espressif.com/sites/default/files/documentation/esp32-c3-mini-1_datasheet_en.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: ESP32-C3_SUPERMINI **Pins:** - 3V3 [pin 3.3] - 5V [pin 5V] - GND [pin G] - GPIO0 [pin 0] - GPIO1 [pin 1] - GPIO10 [pin 10] - GPIO2 [pin 2] - GPIO20 [pin 20] - GPIO21 [pin 21] - GPIO3 [pin 3] - GPIO4 [pin 4] - GPIO5 [pin 5] - GPIO6 [pin 6] - GPIO7 [pin 7] - GPIO8 [pin 8] - GPIO9 [pin 9] ### U3 — [BQ76920PW](https://www.flux.ai/vasyl/bq76920pw.md) - Role: Protection - Role Details: 3S AFE/protector with passive balancing - Manufacturer Name: Texas Instruments - Manufacturer Part Number: BQ76920PW - Datasheet URL: https://octopart.com/opatz8j6/c1?t=IWtIimB8HxuPloIrErLcWPqDVbJFa_F9ZfGQr3kHy9todFUb7dHWBKpboNhg7qUTSmpzMDRXa5ahOrtr1sRw1jZ3P-mJVYvopE0x8dHah9siG4hR--YACHtPzRwZOCFC27AZYVJ8o3Jtad7e7z82oS-T-Ljou72K8xofeAzy4cHCAFciiomga2G9bl4i9w9QRjJu8dNnw1Go19C-R2qTgPWLOZTofcSWbfjhCR_K7qnqpDYr_c0EIw - Part Type: Integrated Circuit **Pins:** - ALERT [pin 20] - BAT [pin 10] - CAP1 [pin 7] - CHG [pin 2] - DSG [pin 1] - NC [pin 11] - REGOUT [pin 8] - REGSRC [pin 9] - SCL [pin 5] - SDA [pin 4] - SRN [pin 19] - SRP [pin 18] - TS1 [pin 6] - VC0 [pin 17] - VC1 [pin 16] - VC2 [pin 15] - VC3 [pin 14] - VC4 [pin 13] - VC5 [pin 12] - VSS [pin 3] ### U4 — [INA180A2IDBVT](https://www.flux.ai/adrian95/ina180a2idbvt.md) - Role Details: Current sense amplifier for pack shunt resistor - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: INA180A2IDBVT - Manufacturer Name: Texas Instruments - Part Type: Integrated Circuit - Role: Sensing (Shunt) - Datasheet URL: https://www.ti.com/lit/ds/symlink/ina180.pdf **Pins:** - GND [pin 2] - IN- [pin 4] - IN+ [pin 3] - OUT [pin 1] - VS [pin 5] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/21ecb34/bms](https://www.flux.ai/21ecb34/bms).* --- *Generated from [https://www.flux.ai/21ecb34/bms](https://www.flux.ai/21ecb34/bms)*