Keszoox
3S / 4S / 5S BMS 100A Li-Ion Battery Protection Board with Balance — 12V / 16.8V / 21V
3S / 4S / 5S BMS 100A Li-Ion Battery Protection Board with Balance 12V / 16.8V / 21V
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3S / 4S / 5S BMS 100A Li-Ion Battery Protection Board with Cell Balancing
This BMS (Battery Management System) protection board provides comprehensive protection for 3S (12.6V), 4S (16.8V), and 5S (21V) lithium-ion and lithium-polymer battery packs at up to 100A continuous discharge current. Built-in cell balancing equalizes individual cell voltages during charging to maximize pack capacity and cycle life.
Key Specifications by Cell Count
| Configuration | Nominal Voltage | Full Charge | Cut-Off (UVP) |
|---|---|---|---|
| 3S (3 cells) | 11.1V | 12.6V | ~9.0V |
| 4S (4 cells) | 14.8V | 16.8V | ~12.0V |
| 5S (5 cells) | 18.5V | 21.0V | ~15.0V |
Protection Features
| Protection | Function | Threshold |
|---|---|---|
| OVP (Overvoltage) | Stops charging when cell exceeds max voltage | 4.25V ±0.05V per cell |
| UVP (Undervoltage) | Disconnects load when cell drops below min | 2.5V ±0.1V per cell |
| OCP (Overcurrent) | Cuts off discharge at excess current | 100A ±20% |
| SCP (Short Circuit) | Instant disconnect on short circuit | <500μs response |
| Cell Balancing | Equalizes cell voltages during charge | Passive balancing |
Why Choose This BMS?
- 100A Continuous Discharge — Handles high-current loads: e-bike motors, power tools, inverters
- Cell Balancing — Passive balancing prevents cell divergence and extends pack cycle life
- All-in-One Protection — OVP + UVP + OCP + SCP in one board; no additional protection circuits needed
- 3S/4S/5S Options — Select the correct cell count for your battery pack voltage
- Low RDS(on) MOSFETs — Minimal voltage drop and heat at high discharge currents
Typical Applications
- E-bike and electric scooter 36V/48V battery pack BMS
- Power tool battery pack (drill, saw, grinder)
- DIY lithium battery pack for solar energy storage
- Electric skateboard and personal mobility device
- Portable power station battery management
- RC car and drone high-current battery protection
Wiring Guide
B- → Battery pack negative terminal.
B1, B2, B3 (B4, B5) → Cell balance wires (between each cell junction).
P- → Load negative terminal (discharge output).
C- → Charger negative terminal (charge input).
Battery positive connects directly to load/charger positive (no BMS switching on positive rail).
FAQ
Q: Can this BMS handle 18650 cells?
A: Yes — compatible with any Li-ion chemistry (18650, 21700, LiPo) with 4.2V per cell nominal. Ensure cell capacity matches the 100A discharge rating (minimum 20Ah pack for 1C discharge).
Q: Does this BMS support simultaneous charge and discharge?
A: Depends on the board version. Boards with separate C- and P- terminals support simultaneous charge/discharge. Boards with combined port do not.
Package Contents
- 1× 3S / 4S / 5S BMS Protection Board (100A, with balancing)
