3S 12V 10A Li-ion Battery Protection Board BMS with 18650 Charger PCB for Electric Drill Motors

$8.68 USD

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3S 12V 10A Li-ion Battery Protection Board BMS — 18650 Charger PCB for Electric Drill & Motors

A 3-series (3S) lithium-ion Battery Management System (BMS) protection board rated at 12V nominal and 10A continuous discharge current. Designed for 3-cell 18650 Li-ion battery packs used in electric drills, power tools, DC motors, and DIY battery projects. Provides essential cell-level protection: overcharge protection (4.25V/cell cutoff), over-discharge protection (2.75V/cell cutoff), overcurrent protection, and short-circuit protection — preventing cell damage and ensuring safe operation across the full charge/discharge cycle.

Technical Specifications

Parameter	Value
Cell Configuration	3S (3 cells in series)
Nominal Pack Voltage	11.1V (3 × 3.7V)
Fully Charged Voltage	12.6V (3 × 4.2V)
Continuous Discharge Current	10A
Peak Discharge Current	15A (short duration)
Overcharge Cutoff (per cell)	4.25V ± 0.05V
Over-discharge Cutoff (per cell)	2.75V ± 0.1V
Short-Circuit Protection	Yes (auto-reset after fault clearance)
Balancing	Passive cell balancing (during charging)
Operating Temperature	−40°C to +85°C
PCB Dimensions	50mm × 15.5mm
MOSFET Configuration	Dual N-channel MOSFET (charge + discharge)

Protection Functions

Overcharge Protection: Disconnects the charge path when any cell reaches 4.25V, preventing electrolyte decomposition and thermal runaway
Over-discharge Protection: Disconnects the load when any cell drops to 2.75V, preventing irreversible capacity loss and copper dissolution
Overcurrent / Short-Circuit Protection: Detects abnormal current and disconnects output within microseconds, protecting both cells and connected equipment
Passive Cell Balancing: Bleeds excess charge from higher-voltage cells during charging to equalise cell voltages across the pack

Typical Applications

Electric Drill Battery Packs: Replace or rebuild 12V Li-ion drill battery packs (Bosch, Makita, Ryobi-compatible form factors) using 18650 cells with this BMS for protection
DC Motor Power Packs: Protected 12V battery supply for DC gear motors, brushless motors, and motor driver modules (L298N, DRV8833, TB6612FNG)
DIY Power Tool Batteries: Build custom 3S 18650 packs for circular saws, jigsaws, and reciprocating saws with OEM-equivalent protection
Robot & Drone Power: Protected 3S Li-ion pack for ground robots, wheeled platforms, and small UAV power systems
Portable Power Banks: 12V output power bank for laptop charging, car jump starters, and 12V appliance power
Solar Storage: 3S Li-ion storage for 12V solar charge controller systems with protected discharge

Wiring Guide

B+: Connect to positive terminal of Cell 3 (top of series stack)
B−: Connect to negative terminal of Cell 1 (bottom of series stack)
BM (B1, B2): Connect to cell junction points between Cell 1/2 and Cell 2/3 for balancing
P+: Load/charger positive output
P−: Load/charger negative output
Charge voltage: 12.6V (3 × 4.2V) — use a dedicated 3S Li-ion charger or CC/CV power supply set to 12.6V

FAQ

Q: Can this BMS charge and discharge simultaneously (common port)?
A: This is a common-port BMS — the same P+/P− terminals are used for both charging and discharging. Do not connect a charger and load simultaneously unless the charger has reverse-current protection.

Q: What 18650 cells are compatible?
A: Any standard 18650 Li-ion cell (3.6V–3.7V nominal, flat-top or button-top). Recommended cells: Samsung 25R, LG HG2, Panasonic NCR18650B, or equivalent. Match cell capacity for best balance performance.

Q: Can I use this BMS for a 12V LiFePO4 pack?
A: No. This BMS is calibrated for Li-ion chemistry (4.2V/cell max, 2.75V/cell min). For LiFePO4 (3.2V nominal, 3.65V max), use a dedicated LiFePO4 BMS with appropriate voltage thresholds.