Overview
JKBMS BD4A20S4P is an active-balance Battery Management System (BMS) for Li-ion, LiFePO4, and LTO battery packs. It supports 7S to 20S battery strings (chemistry-dependent) with 0.4A active balancing and 40A continuous charge/discharge current, and includes built-in Bluetooth for Android/iOS monitoring.
Key Features
- Supported battery strings: 7S to 20S (Li-ion), 8S to 20S (LiFePO4), 12S to 20S (LTO)
- Active balance method: Active Balance (Full State On)
- Balance current: 0.4A (400mA)
- Continuous current: 40A
- Maximum discharge current (MAX 2min): 60A
- Power supply mode: the battery pack is self-powered
- Bluetooth function: Bluetooth built-in; supports Android/iOS phone
- Other interfaces: RS485 (default); CANBUS (customized option)
- Wiring method / wiring output: same port / common port
- Support: short circuit protection; single cell voltage dropout detection; temperature protection; coulomb counter
For wiring guidance, communication integration, or app support, contact https://tsolar.top/ or email service@tsolar.top.
Specifications
| Model | BD4A20S4P |
| Number of Battery Strings (Li-ion) | 7S-20S |
| Number of Battery Strings (LiFePO4) | 8S-20S |
| Number of Battery Strings (LTO) | 12S-20S |
| Balance Method | Active Balance (Full State On) |
| Balance Current | 0.4A |
| Continuous Charge Current | 40A |
| Continuous Discharge Current | 40A |
| Maximum Discharge Current (MAX 2min) | 60A |
| Over Charge Protection Current (ADJ) | 10-40A |
| Conductive Resistance in Main Circuit | 2.8mΩ |
| Size | 110*73*18mm |
| Wiring Output | Common Port |
| Single Cell Voltage Range | 1-5V |
| Single Cell Voltage Detection Range | 0-5V; error < 10mV over full operating range; typical error value < 5mV |
| Voltage Acquisition Accuracy | ±5mV |
| Total Voltage Detection Range | 0-100V; < 0.5%FSR (FSR = full scale) |
| Current Sense Shunt | -150A to 300A; error < 0.5%FSR |
| SoC Estimation Accuracy | Error < 8% (operating conditions) |
| Battery Remaining Capacity | Error range is less than 8% |
| Total Cycle AH Cumulative Value | Half of the charge/discharge value |
| Over Charge Protection Voltage | 1.2-4.35V adjustable |
| Over Charge Release Voltage | 1.2-4.35V adjustable |
| Over Discharge Protection Voltage | 1.2-4.35V adjustable |
| Over Discharge Release Voltage | 1.2-4.35V adjustable |
| Over Current Detect Delay | 2-120S adjustable |
| Quantity of Temperature Detection | 3Pcs |
| Temperature Detection | -40 to 125°C |
| Operating Temperature | -40 to 85°C |
| Storing Temperature | -40 to 95°C |
| Operating Power Consumption | < 5mA (without communication) / 15mA (485/CAN) |
| Standby Power Consumption | < 2mA |
| Other Interfaces (Default) | RS485 |
| Other Interfaces (Customized) | CANBUS |
| Bluetooth Function | Support for Android & iOS phone |
| Temp Protection | YES |
| Short Circuit Protection | YES |
| Coulomb Counter | YES |
Interfaces and Port Labels (from images)
- CANBUS (need customization): GND, CAN_H, CAN_L
- RS485 (by default): GND, RX, TX, VCC
- LCD (by default): K-, K+, GND, B, A, VCC
- Heat Function (need customization): labeled as Heat Function
Protection Items (Six Security Protection)
- Over charge protection: Prevent over-charging affects battery life
- Short circuit protection: Automatic protection when short circuit protection
- Over discharge protection: Prevent the battery from running out
- Over current protection: Prevent the current from exceeding the battery range
- ALL-IN protection: Prevent cable drop or poor contact
- Over temp protection: Prevent the battery from over heating
Smart Energy Working Mode Switching (text from images)
- Storage Mode: In transportation, storage, offline or wireless transmission off mode, the BMS is in storage mode, which does not consume battery pack current.
- Normal Working Mode: When the charger is inserted in the storage mode and off mode, the BMS will immediately return to the normal working mode, and all the protection functions, equalization functions and communication functions will return to normal working.
- Shutdown: To prevent the BMS from wasting power for a long time and damaging the battery pack, the BMS has an automatic shutdown voltage, and the BMS automatically shuts down when a cell falls below the shutdown voltage.
- Standby Mode: When the battery pack is in the static state (no charge and discharge current and no equilibrium current), the BMS will automatically enter the standby state after the set time (1-30 days can be set) is exceeded.
Bluetooth App Notes (text from description)
- Download the specified Bluetooth application and activate the BMS.
- Open the Bluetooth application and find the relevant serial number, then you can check all the data.
Applications
- Battery pack management for Li-ion (7S-20S), LiFePO4 (8S-20S), and LTO (12S-20S)
- Systems requiring active balancing and Bluetooth monitoring
- Installations using RS485 (default) or CANBUS (customized option)
Image Text (Other Models Shown in Provided Images)
- JK-BD6A17S6P: Active Balance BMS; Active Balance Current 0.6A; Adapt Battery Strings: 10S-17S (LTO), 7S-17S (Li-ion), 8S-17S (Lifepo4); Continuous Discharge/Charge Current 60A.
- JK-B2A20S20P-H-C: Active Balance BMS; Active Balance Current 2A; Adapt Battery Strings: 10S-20S (LTO), 7S-20S (Li-ion), 8S-20S (Lifepo4); Continuous Discharge/Charge Current 200A; Support Batteries Heating Function / built-in heating chip; Support RS485 Function Default / built-in CANBUS chip.
Details
Built-in Bluetooth enables real-time pack monitoring and settings from an Android or iOS phone.
RS485 communication comes standard, with CANBUS available as a customized option for system integration.
A compact layered design protects the electronics while keeping wiring and service access straightforward.
Clear port labeling helps with correct wiring for RS485/CAN communication, display/GPS connections, and optional functions.
The mobile app displays total voltage, charge/discharge current, state of charge, and individual cell readings at a glance.
Chemistry selection and detailed cell data support commissioning for Li-ion, LiFePO4, or LTO packs.
Protection features cover common fault conditions including over/under-voltage, short circuit, overcurrent, and over-temperature.
Multiple power modes help reduce standby drain during storage while returning to normal operation when charging resumes.
Use the model comparison table to match string count, balancing current, and current rating to your battery pack requirements.
