18V Li-ion Battery PCB Protection Board for BL1850B BL1840B
18V Li-ion Battery PCB Protection Board for BL1850B BL1840B
18V Power Tool Lithium Battery PCB Protection Board with Indicator
Keep your 18V lithium battery packs running safely and efficiently with this high-performance PCB Protection Board. Engineered for compatibility with BL1850B, BL1840B, and similar 4.0Ah / 5.0Ah battery assemblies, this board delivers rock-solid cell-level monitoring and multi-layered safety cut-off functions — perfect for DIY battery rebuilds and power tool repairs.
Key Features
- Dual Built-In IC Monitoring: Continuously tracks the voltage of every individual cell and logs usage cycles for smarter battery management.
- Full Cell-Level Protection: Independent safeguards for each cell including overheat, overvoltage, undervoltage, overcurrent, and overload automatic cut-off.
- Low Voltage Auto Shut-Off: Designed specifically for 18V power tool battery packs to prevent over-discharge damage during heavy use.
- High Shock Resistance: Reliable, stable performance under demanding conditions — an ideal match for electric torque wrenches, impact drills, and angle grinders.
- Continuous 60A Max Discharge: Supports pulse high current up to short-circuit protection threshold for demanding power tool applications.
- Built-In Charge Indicator: Visual indicator lets you monitor battery status at a glance.
- Color: Green PCB
Technical Specifications
| Rated High Discharge Rate | 15A |
| Max Discharge Current | Continuous 60A (pulse high current supported) |
| Total Discharge Cut-Off Voltage | 13.75V |
| Single Cell Overcharge Protection | 4.25V ± 0.025V |
| Single Cell Overcharge Recovery | 4.1V ± 0.025V |
| Single Cell Over-Discharge Protection | 2.7V ± 0.08V |
| Single Cell Over-Discharge Recovery | 3.0V ± 0.08V |
| Charging High Temp Protection | Over 60°C ± 2°C |
| Overcurrent Protection 1 | ≥100A, 1s delay trigger |
| Overcurrent Protection 2 | ≥180A, 100ms delay trigger |
| Short Circuit Protection | ≥200A |
Pre-Assembly Operation Guide
- New Cell Assembly: Only high-rate power lithium cells are allowed. For 6-cell battery packs, match balance resistors and capacitors to equalize all cell voltages before assembly.
- Old Battery Pack Repair: Test the voltage of every single cell. If voltages are inconsistent, charge each cell separately to reach a uniform voltage before soldering.
⚠️ Important: All battery cells must be balanced to the same voltage before soldering to the PCB board. Unbalanced cells may cause improper function or trigger safety cut-offs.
Package Contents
- 1 × 18V Lithium Battery PCB Protection Board
Note: PCB board only. Batteries, cells, and other assembly components are not included.
Made in Mainland China.
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Learn more: EPA guidance on lithium-ion battery handling
Frequently Asked Questions
Q: Is this PCB protection board compatible with Makita BL1850B and BL1840B battery packs?
A: Yes, this 18V lithium battery PCB protection board is designed to be compatible with BL1850B, BL1840B, and similar 18V 4.0Ah / 5.0Ah lithium battery pack assemblies commonly used in power tools. Always verify cell count and configuration before assembly.
Q: What protections does this PCB board provide for my battery cells?
A: This board provides comprehensive cell-level protection including overvoltage, undervoltage, overcurrent, overload, overheating (over 60°C), and short-circuit (≥200A threshold) automatic cut-off functions — independently monitored for each cell via dual built-in ICs.
Q: Do I need to balance the cells before soldering them to this PCB protection board?
A: Yes, this is critical. All battery cells must be charged and balanced to the same voltage before soldering to the PCB board. Unbalanced cells can cause errors in the protection circuitry. For old battery pack repairs, test and individually charge each cell to achieve uniform voltage prior to assembly.
Q: What types of power tools is this protection board suitable for?
A: This PCB board is ideally matched for use with electric torque wrenches, impact drills, angle grinders, and a wide range of other 18V power tool equipment that use compatible lithium battery packs.
Production & Packaging Notice
To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.