JK-B4A24S Active Battery Equalizer: Complete Setup Guide, Wiring, Parameters & Installation
Last updated: July 2026 | Applicable to firmware V11.1.1 and above
The JK-B4A24S is a smart active battery equalizer designed by Chengdu Jikong Technology (JKBMS) for large-capacity series lithium battery packs. Using ultracapacitor-based active energy transfer, it delivers a constant 4A balancing current across 2 to 24 series cells with ±3mV voltage acquisition accuracy. This guide covers everything you need to know about the JK-B4A24S: features, specifications, pinout, wiring, installation, and Bluetooth APP configuration.
Table of Contents
- What Is the JK-B4A24S Active Equalizer?
- Key Features and Specifications
- Supported Battery Types and Series
- How Active Equalization Works
- Connector Pinout and Interface Definition
- Physical Dimensions
- Installation Guide
- Power Supply Requirements
- Bluetooth APP Setup and Parameter Configuration
- Default Parameters by Battery Chemistry
- Communication Options: RS485 and CAN
- Safety Features and Undervoltage Shutdown
- Wiring Diagram Summary
1. What Is the JK-B4A24S Active Equalizer?
The JK-B4A24S is an active battery management device built for lithium battery packs ranging from 2 to 24 series cells. Unlike passive balancers that dissipate excess energy as heat, the JK-B4A24S uses ultracapacitors as a medium to actively transfer energy from high-voltage cells to low-voltage cells. This approach is significantly more efficient and extends battery cycle life.
The equalizer supports all mainstream lithium battery chemistries including LiFePO4 (LFP), NCM ternary lithium, and LTO (lithium titanate). It is widely used in small sightseeing vehicles, electric scooters, shared vehicles, high-power energy storage systems, base station backup power, and solar power stations. It is also suitable for battery maintenance and repair applications.
2. Key Features and Specifications
The JK-B4A24S comes with a robust set of features designed for professional battery management:
- Active equalization current: Constant 4A energy transfer, independent of cell voltage delta
- Voltage acquisition range: 1V to 5V per cell with ±3mV accuracy
- Bluetooth connectivity: Built-in Bluetooth with dedicated mobile APP for real-time monitoring and parameter adjustment
- LED status indicator: Visual Bluetooth connection status (steady on = connected, blinking = disconnected)
- Optional temperature acquisition: External temperature sensor support via XH-2AW connector
- Optional communication: RS485 and CAN bus support via MX3.0-2x9AWC connector
- Undervoltage shutdown: Automatic shutdown when first cell voltage drops below 2.2V±0.2V
- Compact design: 176.6×127.3×23.5mm, 712g weight
Basic Parameters
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage | 9 - 100 | V |
| Operating Power Consumption | ≤ 1000 | mW |
| Operating Temperature | -30 to +70 | °C |
| Maximum Balancing Current | 4 | A |
| Shutdown Threshold Voltage | 2.2 ± 0.2 | V |
| Dimensions (L×W×H) | 176.6 × 127.3 × 23.5 | mm |
| Weight | 712 | g |
3. Supported Battery Types and Series
The JK-B4A24S supports 2 to 24 series cells across all major lithium battery chemistries. The following table summarizes the compatibility:
| Product Model | Battery Chemistry | Supported Series |
|---|---|---|
| JK-B4A24S | Ternary Lithium (NCM) | 2 - 24S |
| Lithium Iron Phosphate (LiFePO4) | 2 - 24S | |
| Lithium Titanate (LTO) | 2 - 24S |
4. How Active Equalization Works
The JK-B4A24S uses active equalization technology based on ultracapacitor energy transfer. The working principle is straightforward:
- The equalizer continuously monitors the voltage of each cell in the battery pack.
- When the voltage difference between any two cells exceeds the user-defined trigger threshold (default 10mV), the equalizer activates.
- Energy is transferred from the high-voltage cell to the low-voltage cell through the ultracapacitor medium.
- The equalization stops automatically when the voltage difference falls below the set threshold.
Important note: The default balancing current is 4A (maximum). Users can adjust this based on battery capacity, but it is recommended not to exceed 0.2C of the battery capacity. If balancing is not needed, it can be turned off via the APP BMS control page.
5. Connector Pinout and Interface Definition
The JK-B4A24S features four main connectors plus a Bluetooth LED indicator:
P1 - Balance Wire Connector (XH-15AW, 15-pin)
Connects to cell balance wires B1 through B14:
| Pin | Name | Definition |
|---|---|---|
| 1 | B- | Total negative battery terminal |
| 2 | B1 | Positive of 1st cell string |
| 3 | B2 | Positive of 2nd cell string |
| 4 | B3 | Positive of 3rd cell string |
| 5 | B4 | Positive of 4th cell string |
| 6 | B5 | Positive of 5th cell string |
| 7 | B6 | Positive of 6th cell string |
| 8 | B7 | Positive of 7th cell string |
| 9 | B8 | Positive of 8th cell string |
| 10 | B9 | Positive of 9th cell string |
| 11 | B10 | Positive of 10th cell string |
| 12 | B11 | Positive of 11th cell string |
| 13 | B12 | Positive of 12th cell string |
| 14 | B13 | Positive of 13th cell string |
| 15 | B14 | Positive of 14th cell string |
P2 - Balance Wire Connector (XH-11AW, 11-pin)
Connects to cell balance wires B15 through B24 plus power:
| Pin | Name | Definition |
|---|---|---|
| 1 | B15 | Positive of 15th cell string |
| 2 | B16 | Positive of 16th cell string |
| 3 | B17 | Positive of 17th cell string |
| 4 | B18 | Positive of 18th cell string |
| 5 | B19 | Positive of 19th cell string |
| 6 | B20 | Positive of 20th cell string |
| 7 | B21 | Positive of 21st cell string |
| 8 | B22 | Positive of 22nd cell string |
| 9 | B23 | Positive of 23rd cell string |
| 10 | B24 | Positive of 24th cell string |
| 11 | B+ | Equalizer power supply - connect to any cell 13-24 positive, or external 9-100V DC |
P3 - Temperature Sensor Connector (XH-2AW, 2-pin)
| Pin | Name | Definition |
|---|---|---|
| 1 | T1A | Temperature sensor pin A |
| 2 | T1B | Temperature sensor pin B |
P4 - Communication Connector (MX3.0-2x9AWC, 18-pin)
| Pin | Name | Definition |
|---|---|---|
| 1-4 | --- | Reserved |
| 5 | 485-N | RS485-B signal negative |
| 6 | 485-P | RS485-A signal positive |
| 7-13 | --- | Reserved |
| 14 | CAN-N | CAN_L signal negative |
| 15 | CAN-P | CAN_H signal positive |
| 16-18 | --- | Reserved |
D1 - Bluetooth LED Indicator
- Steady ON: Bluetooth connected to the active equalizer
- Blinking: Bluetooth disconnected
6. Physical Dimensions
The JK-B4A24S has a compact aluminum housing suitable for integration into battery PACKs:
- Length: 176.6 mm
- Width: 127.3 mm
- Height: 23.5 mm
- Weight: 712 g
7. Installation Guide
7.1 Single Equalizer Installation
A single JK-B4A24S equalizer is suitable for battery packs with 2 to 24 series cells. Follow these steps:
- Confirm the battery pack voltage. If the voltage is above 20V, connect B+ to any positive terminal of cells 13-24.
- If the battery pack voltage is below 20V, an external 9V to 100V DC power supply is required.
- If the battery pack voltage is below 9V, use an external power supply connected directly to the B+ terminal.
- Connect the balance wires from P1 and P2 to the corresponding cell terminals (B- to B24).
- Connect the temperature sensor to P3 if temperature monitoring is required.
- Connect RS485 or CAN communication cables to P4 if external communication is needed.
- Secure the equalizer in the battery pack enclosure.
7.2 Cascading Installation (Multiple Equalizers)
The JK-B4A24S supports cascading for battery packs with more than 24 series cells. Multiple equalizers can be connected in a cascading configuration to extend the balancing capability beyond 24 cells. Refer to the cascading wiring diagram in the full manual for detailed connection instructions.
8. Power Supply Requirements
| Battery Pack Voltage | Power Supply Method |
|---|---|
| 20V - 100V (13S - 24S typical) | Self-powered via B+ connected to cell 13-24 positive |
| 9V - 20V (3S - 6S typical) | External 9V-100V DC power supply or boost module required |
| Below 9V (2S typical) | External 9V-100V DC power supply required |
9. Bluetooth APP Setup and Parameter Configuration
9.1 APP Installation
Download the Jikong BMS APP by scanning the QR code provided with the product. The Android version requires Android 7.0 or higher. The APP is also available for iOS devices.
9.2 Device Activation
Before powering on, verify:
- Balance wire connections are correct
- Power supply is within the 9V-100V range
- The equalizer is securely mounted
Power on the equalizer by connecting the power cable to the terminal. The JK-B4A24S has no physical power switch and starts automatically. The first power-on requires the first cell voltage to be above 2.4V.
9.3 Parameter Setting
After installing the APP and connecting via Bluetooth:
- Open the APP and connect to the equalizer via Bluetooth.
- Navigate to Parameter Settings and select your battery chemistry type (LiFePO4, Li-ion, or LTO).
- Configure basic parameters: number of cells, battery capacity, trigger equalization differential pressure, voltage calibration, and current calibration.
- Set the balance trigger pressure difference (mV). Default is 10mV.
- Adjust the balancing current if needed (default 4A, max 4A).
10. Default Parameters by Battery Chemistry
| Parameter | Li-ion (NCM) | LiFePO4 (LFP) | LTO | Unit |
|---|---|---|---|---|
| Balancing Initial Voltage | 3.0 | 3.0 | 2.0 | V |
| Maximum Balancing Current | 4 | 4 | 4 | A |
| Cell Overcharge Voltage | 4.2 | 3.6 | 2.7 | V |
| Trigger Balancing Differential | 0.01 | 0.01 | 0.01 | V |
| Device Address | 1 | 1 | 1 | - |
11. Communication Options: RS485 and CAN
The JK-B4A24S supports optional RS485 and CAN bus communication via the P4 connector. These are add-on features that can be selected based on your system requirements.
- RS485: Uses pins 5 (485-N) and 6 (485-P) on P4. Suitable for long-distance communication with host systems.
- CAN: Uses pins 14 (CAN-N) and 15 (CAN-P) on P4. Ideal for automotive and industrial applications.
To switch between RS485 and CAN, use the Jikong APP BMS control page to toggle the multiplexed port selection. For detailed communication protocols, refer to the Jikong Active Equalizer Communication Protocol document.
12. Safety Features and Undervoltage Shutdown
The JK-B4A24S includes an undervoltage shutdown safety feature:
- Shutdown condition: When the voltage of the first cell string drops below 2.2V ± 0.2V, the equalizer automatically shuts down to prevent over-discharge damage.
- First power-on requirement: The first cell must have a voltage above 2.4V for initial activation.
Always verify balance wire connections and power supply range before powering on. Incorrect connections can cause abnormal operation or permanent damage.
13. Wiring Diagram Summary
Key wiring rules for the JK-B4A24S:
- B- (Pin 1 of P1): Connect to the total negative terminal of the battery pack.
- B1 to B24 (P1 and P2): Connect to the positive terminal of each corresponding cell string.
- B+ (Pin 11 of P2): Power supply input. For 13-24S packs, connect to any cell 13-24 positive. For lower voltage packs, use external 9-100V DC.
- T1A/T1B (P3): Optional temperature sensor connection.
- 485-N/485-P (P4 pins 5-6): Optional RS485 communication.
- CAN-N/CAN-P (P4 pins 14-15): Optional CAN communication.
Download the Full Manual and APP
For the complete wiring diagrams, cascading installation instructions, communication protocol documentation, and the latest firmware, visit our download center:
Download Center - JK-B4A24S Manuals, APP & Firmware
Related Products
- JK-B4A24S Active Equalizer - 4S to 24S Support
- JKBMS 8S-16S Smart BMS Series
- JK Active Balancer & Equalizer Accessories
FAQ
Q: Can I use the JK-B4A24S on a 12V (4S LiFePO4) battery?
A: Yes, but you need an external 9V-100V DC power supply since a 4S LiFePO4 pack voltage (~12.8V) is below the 20V self-power threshold.
Q: What is the maximum number of cells the JK-B4A24S can balance?
A: A single unit supports 2 to 24 series cells. For more than 24 cells, use cascading mode with multiple units.
Q: Does the JK-B4A24S require an external BMS?
A: The JK-B4A24S is an active equalizer, not a full BMS. It handles cell balancing but does not provide overcharge, over-discharge, or short-circuit protection. Use it alongside a JKBMS protection board for complete battery management.
Q: How do I update the firmware?
A: Firmware updates are performed via the Jikong BMS APP over Bluetooth. Download the latest firmware from the download center.
This guide is based on the JK-B4A24S Product Specification V11.1.1 published by Chengdu Jikong Technology Co., Ltd. Specifications are subject to change without notice. For the most up-to-date information, always refer to the official documentation.