JK-BD4AxxS-12P Series Active Balancing Lithium BMS Complete Specifications & Operation Guide

1. Product Overview

1.1 BMS General Introduction

The JK-BD4AxxS-12P series is an intelligent lithium battery protection board customized for large-capacity series lithium battery packs. It integrates high-precision voltage sampling, 0.4A high-current active balancing, full-range charge & discharge safety protection, built-in coulomb counter, Bluetooth communication, and reserved UART/GPS expansion ports. It supports ternary lithium, LiFePO4 lithium iron phosphate, and lithium titanate (LTO) cells.

This BMS adopts self-developed energy-transfer active balancing technology with independent intellectual property rights, delivering a max continuous balancing current of 0.4A. The high-current balancing mechanism maximizes cell consistency, extends battery cycle range, and slows down cell aging and capacity decay.

It is equipped with a dedicated mobile APP compatible with Android and iOS. Users can connect the board via Bluetooth to monitor real-time battery status, edit all protection parameters, and control charge/discharge switches. With compact dimensions and abundant expansion interfaces, this BMS is widely applied to mobility scooters, shared EVs, high-power off-grid energy storage, solar power stations, and telecom base backup battery packs.

1.2 Core Feature List

• LED Bluetooth connection indicator (steady on when paired, flashing disconnected)
• Wireless Bluetooth APP remote control for iOS & Android
• Built-in coulomb counter to calculate real-time remaining SOC capacity
• High-precision cell voltage sampling (±3mV error)
• High-precision real-time current detection
• Dedicated LCD display expansion port for offline data viewing
• Timestamped fault log storage for overcharge, overdischarge, short-circuit & overtemperature records
• Optional RS485 industrial communication bus
• Optional CAN bus industrial communication bus
• Optional multi-battery parallel expansion module
• Optional sound & light fault alarm module
• Optional low-temperature heating control module
• Reserved UART port for external GPS positioning module
• Full standard protection: charge overvoltage, discharge undervoltage, charge/discharge overcurrent
• Overtemperature protection for charging & discharging; low-temperature charging lockout
• Hardware microsecond-level short-circuit auto-cutoff protection

2. Product Selection Guide

2.1 Standard Function Configuration Table

2.2 Compatible Battery Cell Series Range

2.3 Full Optional Model Suffix Explanation

JK-BD4A24S-12P Series (21~24 Cells)

• JK-BD4A24S-12P: Standard Base Version
• JK-BD4A24S-12PC: Standard + CAN Communication
• JK-BD4A24S-12PR: Standard + RS485 Communication
• JK-BD4A24S-12PH: Standard + Heating Module
• JK-BD4A24S-12PHC: Heating + CAN Bus
• JK-BD4A24S-12PHR: Heating + RS485 Bus
• JK-BD4A24S-12PHCR: Heating + CAN + RS485 Dual Bus

JK-BD4A20S-12P Series (7~20 Cells)

• JK-BD4A20S-12P: Standard Base Version
• JK-BD4A20S-12PC: Standard + CAN Communication
• JK-BD4A20S-12PR: Standard + RS485 Communication
• JK-BD4A20S-12PH: Standard + Heating Module
• JK-BD4A20S-12PHC: Heating + CAN Bus
• JK-BD4A20S-12PHR: Heating + RS485 Bus
• JK-BD4A20S-12PHCR: Heating + CAN + RS485 Dual Bus

3. Detailed Function Operation Instructions

3.1 Active Balancing System

This BMS adopts energy-transfer active balancing: it moves excess energy from higher-voltage cells to low-voltage cells to shrink inter-cell voltage gaps. Before enabling balancing, download the official Jikong BMS APP and complete battery parameter setup.

Setup steps in APP: Select battery chemistry type, input cell series count, rated capacity, and balancing trigger differential pressure (default 10mV). Balancing auto activates when cell voltage gap exceeds the set threshold and stops automatically after voltage levels normalize.

Max fixed balancing current is 0.4A; recommended balancing current shall not exceed 0.2C of battery nominal capacity. Users can fully disable balancing via the BMS control page in APP if not required.

3.2 UART GPS & LCD Display Ports

The reserved UART serial port supports third-party GPS modules for battery anti-theft and remote location tracking. The dedicated LCD screen interface allows offline real-time viewing of cell voltage, current, temperature, and SOC without a smartphone, convenient for field maintenance.

3.3 Optional Low-Temperature Heating Function

The heating module runs with a rated 10A heating current to warm batteries under frigid conditions, preventing severe capacity loss and charging failure at low temperatures. Users can toggle heating on/off directly in the APP BMS panel.

Safety requirement: Connect a 45℃~65℃ normally closed thermal switch in series as secondary overheat protection; the circuit will cut heating power once temperature exceeds the safety threshold to avoid thermal runaway risks.

3.4 Sound & Light Fault Alarm

With optional alarm hardware, the BMS triggers audible + visual alerts when detecting overcharge, overdischarge, overtemperature, or short-circuit risks to remind operators to cut off power and inspect the battery pack promptly.

3.5 Multi-Battery Parallel Expansion

The parallel module allows multiple battery packs to work together for large-capacity energy storage systems. To enable parallel mode, turn off the "Charge Current Limit Disable" switch inside the APP and match the dedicated parallel hardware module.

3.6 Charge Overvoltage Protection & Auto Recovery

Users set single-cell overcharge cutoff voltage and recovery voltage in APP. If any cell hits the overcharge threshold, charging power is instantly cut off. Charging resumes only after all cell voltages drop below the recovery value to eliminate cell swelling risks caused by overcharging.

3.7 Discharge Undervoltage Protection & Auto Recovery

Three adjustable voltage thresholds: undervoltage protection limit, undervoltage recovery voltage, and full auto-shutdown voltage. Discharge circuit cuts off once any cell falls below protection value; discharge restores after charging lifts cell voltages above recovery level. If single-cell voltage hits the auto-shutdown threshold, the whole board fully powers down to protect cells from permanent damage.

3.8 Charge & Discharge Overcurrent Protection

Customizable continuous current limit, fault delay time, and auto-reset delay for both charging and discharging. Protection activates after preset delay when current exceeds rated value; the board retries charging/discharging after the release timer expires to avoid false triggers from transient inrush current. The maximum configurable continuous discharge current is 120A.

3.9 Multi-Stage Temperature Protection

• Charge overtemperature: Cut off charging at 70℃, resume cooling below 60℃
• Discharge overtemperature: Cut off discharging at 70℃, resume cooling below 60℃
• Low-temperature charging lockout: Disable charging below -20℃; resume above -10℃
• MOS tube overtemperature cutoff at 100℃, recovery at 80℃

Users operating in cold northern regions are advised to install the optional heating module to safeguard cell lifespan.

3.10 Hardware Short-Circuit Protection

Microsecond instant short-circuit detection without manual trigger current setup. The main circuit cuts power immediately upon short-circuit on charger or load terminals, auto-resets after 30 seconds. If large-capacity loads trigger false short-circuit alarms on startup, increase the short-circuit delay parameter in the APP to eliminate misfire.

3.11 Emergency Power Mode

If the board locks charge/discharge due to overtemperature, overdischarge, overcharge, or broken cell tap wires, activate Emergency Mode in the APP. This forces the charge and discharge circuits open for a full 30 minutes of temporary power supply, preventing vehicle breakdown during field operation. Even if cells hit auto-shutdown voltage, power remains available for the full 30-minute window.

3.12 Intelligent Sleep Power-Saving Mode

If charge/discharge current stays below 1A for 26 consecutive standby hours, the board enters low-power sleep to reduce self-consumption drain on the battery pack. Three wake-up methods: connect charger power, press optional screen activation button, or plug in LCD display hardware.

3.13 CAN & RS485 Industrial Communication

With optional dual communication ports, users can switch between CAN and RS485 via the APP multiplex port selector. Custom device address and communication protocol are supported for integration with inverters, industrial control cabinets, and large energy station host systems. Full communication protocol documents are available in the download center.

4. Main Electrical Hardware Parameters

4.1 Factory Default Voltage & Timing Parameters

Ternary Li-ion Default Settings

Balancing start voltage: 3V; Single overcharge voltage: 4.2V; Overcharge recovery: 4.18V; Undervoltage protection: 2.82V; Undervoltage recovery: 2.85V; Auto shutdown: 2.8V; SOC 0% voltage: 2.9V; SOC 100% voltage: 4.18V; Balancing trigger gap: 10mV.

LiFePO4 Default Settings

Balancing start voltage: 3V; Single overcharge voltage: 3.6V; Overcharge recovery: 3.55V; Undervoltage protection: 2.6V; Undervoltage recovery: 2.65V; Auto shutdown: 2.5V; SOC 0% voltage: 2.6V; SOC 100% voltage: 3.5V; Balancing trigger gap: 10mV.

LTO Lithium Titanate Default Settings

Balancing start voltage: 2V; Single overcharge voltage: 2.7V; Overcharge recovery: 2.65V; Undervoltage protection: 1.8V; Undervoltage recovery: 1.85V; Auto shutdown: 1.7V; SOC 0% voltage: 1.85V; SOC 100% voltage: 2.65V; Balancing trigger gap: 10mV.

Unified timing parameters: Charge/discharge overcurrent delay 30s, overcurrent release 60s; Short-circuit delay 5us, short-circuit reset 30s; All overheat protection cutoff 70℃, recovery 60℃; Low-temperature charge lockout -20℃, resume -10℃; MOS overheat cutoff 100℃, recover 80℃; Default device communication address: 0.

5. Interface Definition & Installation Wiring Guide

5.1 Main Sampling Connectors P1 & P2

P1 (HY2.0-15P): B- total negative, B1~B14 single cell positive taps

P2 (HY2.0-11P): B15~B24 cell taps, B+ main positive power input for BMS

5.2 Temperature Sensor Ports P3, P4

P3: 2 built-in NTC sensor pins T1A, T1B, T2A, T2B

P4: Optional 4-channel external temperature probes T3A, T3B, T4A, T4B

5.3 Expansion Functional Ports

• P5 UART GPS Port: GND, RX, TX, VGPS power supply
• P6 Buzzer Alarm Port: GND, VCC alarm power
• P7 CAN/RS485 Communication: CAN_H, CAN_L, RS485_A, RS485_B
• P8 LCD Display Port: Activation K+/K-, GND, RS485 A/B, screen VCC
• P9 Parallel Module Port: P-status feedback, P-EN enable signal, signal GND
• Heating Wire Terminal: HT- heating negative output (16AWG orange cable)

5.4 High-Current Terminals

• B- M6 screw terminal: Directly connect battery pack total negative
• P- M6 screw terminal: Common negative for external charger & load

Installation Remarks: Secure the board flatly; strictly match tap wire sequence with cell series count. Incorrect B+/B- or B1~B24 wiring will permanently burn the protection board.

6 APP Download & Device Activation Tutorial

6.1 APP Installation

Scan the official QR code printed on the product to download Jikong BMS APP. Android requires Android 7.0 or above, fully compatible with all iOS devices.

6.2 Three Activation Methods

1. Charge Activation (Default): Connect a charger with output voltage 2V higher than the battery pack to power on the BMS automatically after wiring completion
2. Button Activation: Short press activation key on optional LCD screen kit
3. Display Wake-up: Plug in LCD screen cable to auto-power the board

Pre-activation Check: Double-check all sampling taps and B-/P- heavy current wiring to avoid short-circuit damage to components.

6.3 Parameter Configuration Process

1. Turn on mobile Bluetooth, search and pair the target BMS device
2. Select battery chemistry: Ternary / LiFePO4 / LTO
3. Fill cell series number and nominal battery capacity
4. Adjust charge/discharge current limits, temperature thresholds, voltage difference parameters per usage scenario
5. Save settings; parameters sync to board and take effect after reboot

7. Application Scenario Summary

The JK-BD4AxxS-12P series active balancing BMS is suitable for low-speed sightseeing carts, shared electric vehicles, RV energy storage power stations, household off-grid solar systems, outdoor high-power battery packs, telecom base backup power, and small industrial energy storage PACKs.

0.4A professional active balancing paired with comprehensive multi-layer safety protection extends battery service life and eliminates overcharge/overdischarge risks. Rich optional CAN/RS485/GPS/heating/alarm interfaces satisfy both consumer DIY and industrial energy storage integration project requirements.