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5S BMS 20A Li-Ion Battery Protection Board 18V–21V for Power Tools
5S BMS 20A Li-Ion Battery Protection Board 18V–21V for Power Tools
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5S BMS 20A Li-Ion Battery Protection Board — 18V–21V Power Tool Packs
This 5S BMS (Battery Management System) protection board is designed for 5-cell series Li-ion battery packs (18V nominal, 21V fully charged) used in power tools. It provides comprehensive protection including overcharge, over-discharge, overcurrent, and short-circuit protection, plus passive cell balancing to extend pack life.
Key Specifications
| Parameter | Value |
|---|---|
| Cell Configuration | 5S (5 cells in series) |
| Nominal Voltage | 18V (5 × 3.6V) |
| Full Charge Voltage | 21V (5 × 4.2V) |
| Continuous Discharge Current | 20A |
| Peak Discharge Current | 40A (short burst) |
| Overcharge Protection | 4.25V ±0.05V per cell |
| Over-Discharge Protection | 2.5V ±0.1V per cell |
| Overcurrent Protection | ~25A (adjustable) |
| Short-Circuit Protection | Yes — auto-recovery |
| Cell Balancing | Passive (during charging) |
| Operating Temperature | −40°C to +85°C |
Why Choose This 5S BMS?
- Full Protection Suite — Overcharge, over-discharge, overcurrent, and short-circuit in one board
- Passive Cell Balancing — Equalizes cell voltages during charging to maximize capacity and cycle life
- 20A Continuous — Handles high-drain power tool loads (drills, saws, grinders)
- Auto-Recovery — Automatically resets after short-circuit or over-discharge condition clears
- Wide Temperature Range — −40°C to +85°C for demanding tool environments
Typical Applications
- 18V power tool battery pack rebuild (Makita, DeWalt, Bosch compatible packs)
- DIY 5S Li-ion e-bike battery protection
- 5S LiPo battery management for RC vehicles
- 18V cordless tool battery replacement BMS
- Custom 18V battery pack for robotics and automation
Wiring Guide
Connect B− to battery pack negative. Connect B1–B4 balance wires to cell junctions (between each cell). Connect P− to load/charger negative. B+ and P+ share the pack positive terminal.
FAQ
Q: Is this BMS compatible with 18650 cells?
A: Yes — designed for 5× 18650 Li-ion cells in series (or equivalent Li-ion chemistry at 3.6V/4.2V per cell).
Q: Can I use this BMS for charging and discharging simultaneously?
A: This is a common-port BMS — charge and discharge share the same P+/P− terminals. Simultaneous charge/discharge is not recommended.
Package Contents
- 1× 5S 20A Li-Ion BMS Protection Board
- ★Product Description
- ★About us
- ★Custom cable
5S BMS 20A Li-Ion Battery Protection Board — 18V–21V Power Tool Packs
This 5S BMS (Battery Management System) protection board is designed for 5-cell series Li-ion battery packs (18V nominal, 21V fully charged) used in power tools. It provides comprehensive protection including overcharge, over-discharge, overcurrent, and short-circuit protection, plus passive cell balancing to extend pack life.
Key Specifications
| Parameter | Value |
|---|---|
| Cell Configuration | 5S (5 cells in series) |
| Nominal Voltage | 18V (5 × 3.6V) |
| Full Charge Voltage | 21V (5 × 4.2V) |
| Continuous Discharge Current | 20A |
| Peak Discharge Current | 40A (short burst) |
| Overcharge Protection | 4.25V ±0.05V per cell |
| Over-Discharge Protection | 2.5V ±0.1V per cell |
| Overcurrent Protection | ~25A (adjustable) |
| Short-Circuit Protection | Yes — auto-recovery |
| Cell Balancing | Passive (during charging) |
| Operating Temperature | −40°C to +85°C |
Why Choose This 5S BMS?
- Full Protection Suite — Overcharge, over-discharge, overcurrent, and short-circuit in one board
- Passive Cell Balancing — Equalizes cell voltages during charging to maximize capacity and cycle life
- 20A Continuous — Handles high-drain power tool loads (drills, saws, grinders)
- Auto-Recovery — Automatically resets after short-circuit or over-discharge condition clears
- Wide Temperature Range — −40°C to +85°C for demanding tool environments
Typical Applications
- 18V power tool battery pack rebuild (Makita, DeWalt, Bosch compatible packs)
- DIY 5S Li-ion e-bike battery protection
- 5S LiPo battery management for RC vehicles
- 18V cordless tool battery replacement BMS
- Custom 18V battery pack for robotics and automation
Wiring Guide
Connect B− to battery pack negative. Connect B1–B4 balance wires to cell junctions (between each cell). Connect P− to load/charger negative. B+ and P+ share the pack positive terminal.
FAQ
Q: Is this BMS compatible with 18650 cells?
A: Yes — designed for 5× 18650 Li-ion cells in series (or equivalent Li-ion chemistry at 3.6V/4.2V per cell).
Q: Can I use this BMS for charging and discharging simultaneously?
A: This is a common-port BMS — charge and discharge share the same P+/P− terminals. Simultaneous charge/discharge is not recommended.
Package Contents
- 1× 5S 20A Li-Ion BMS Protection Board
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