5S BMS 18V 21V 20A Li-Ion Battery Protection Circuit Board
5S BMS 18V 21V 20A Li-Ion Battery Protection Circuit Board
5S BMS Battery Protection Circuit Board – 18V/21V 20A for Li-Ion Power Tool Packs
Keep your 5-series lithium battery packs running safely and efficiently with this compact 5S BMS (Battery Management System) Protection Circuit Board. Designed specifically for 18V/21V electric power tools — including cordless drills, screwdrivers, and impact drivers — this module monitors voltage, current, and temperature in real time to guard your battery investment.
Key Features
- 5S Li-Ion Compatible: Works with lithium iron phosphate, lithium manganese, lithium cobalt, ternary, and other common 5-series lithium chemistries.
- Multi-Layer Protection: Built-in overcharge protection, over-discharge protection, and short-circuit protection for safe operation at all times.
- Dedicated 5S IC Processor: Uses a specialized integrated circuit to monitor each cell's voltage, charge/discharge current, and ambient temperature in real time.
- Adjustable Discharge Current: Discharge current is adjustable up to 10A, with overdischarge protection triggering at 35±10A.
- Ultra-Low Power Consumption: Working current of just ~25µA and quiescent current of ~6µA — minimal drain on your battery at rest.
- Waterproof & Moisture-Resistant Coating: Protective conformal coating on components guards against water, condensation, and humidity.
- Compact & Easy to Install: Slim profile at just 46×40×3.6mm fits neatly inside standard power tool battery housings.
Technical Specifications
| Operating Voltage | 18V |
| Charging Voltage | 21V – 24V |
| Charging Current | 1A – 3A |
| Discharge Current | 10A (adjustable) |
| Overdischarge Protection Current | 35 ± 10A |
| Board Dimensions | 46 × 40 × 3.6 mm |
| Working Current | ~25µA |
| Quiescent Current | ~6µA |
| Compatible Battery Types | Li-Ion (LiFePO4, LiMn, LiCoO2, Ternary, etc.) |
| Application | 5S 21V power tools, cordless drills, screwdrivers |
What's in the Box
- 1 × 5S BMS 18V/21V 20A Li-Ion Battery Protection Circuit Board
Note: Battery, charger, and power tool are NOT included.
Made in Mainland China.
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Frequently Asked Questions
Q: What battery types is this 5S BMS protection board compatible with?
A: This 5S BMS circuit board is compatible with a wide range of 5-series lithium battery chemistries, including lithium iron phosphate (LiFePO4), lithium manganese (LiMn), lithium cobalt (LiCoO2), and ternary lithium batteries. It is designed for 18V/21V battery packs commonly used in cordless power tools.
Q: Does this board protect against short circuits and overcharging?
A: Yes. The board includes built-in overcharge protection, over-discharge protection, and short-circuit protection. The dedicated 5S IC processor continuously monitors each cell's voltage and current, cutting off the circuit if unsafe conditions are detected.
Q: What are the dimensions of this BMS board, and will it fit in my power tool battery pack?
A: The board measures 46mm × 40mm × 3.6mm (length × width × height), making it compact enough to fit inside most standard 21V cordless power tool battery housings, including those for cordless drills and electric screwdrivers.
Q: Is the protection board waterproof?
A: The board's components are coated with a protective conformal coating that provides resistance against water, moisture, and condensation — helping ensure reliable performance even in workshop environments where humidity may be a factor.