{"product_id":"21v-8mos-bms-balance-protection-board-18650-battery-power-tools","title":"21V 8-MOS BMS Balance Protection Board for 18650 Power Tools","description":"\u003cp\u003eKeep your cordless power tools running safely and efficiently with this \u003cstrong\u003e21V 8-MOS Battery Management \u0026amp; Balance Protection Board\u003c\/strong\u003e, designed specifically for 18650 lithium-ion battery packs used in angle grinders, chainsaws, electric wrenches, and other DIY power tools.\u003c\/p\u003e\n\n\u003cp\u003eBuilt from durable metal components, this protection board features 8 MOSFET transistors for robust overcharge, over-discharge, over-current, and short-circuit protection — helping extend battery life and maintain consistent performance across your tools.\u003c\/p\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e21V Rated Voltage\u003c\/strong\u003e — compatible with standard 5-cell 18650 lithium-ion battery configurations\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e8-MOS Design\u003c\/strong\u003e — eight MOSFET transistors deliver stable current handling and efficient switching\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBalancing Function\u003c\/strong\u003e — actively balances cell voltages to maximize pack longevity\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMulti-Layer Protection\u003c\/strong\u003e — guards against overcharge, over-discharge, over-current, and short circuits\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMetal Construction\u003c\/strong\u003e — sturdy, heat-resistant build for reliable use in demanding workshop environments\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWide Compatibility\u003c\/strong\u003e — suitable for angle grinders, chainsaws, electric wrenches, drills, and other 21V cordless power tools\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDIY Friendly\u003c\/strong\u003e — ideal for battery pack repairs, custom builds, and power tool upgrades\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVoltage:\u003c\/strong\u003e 21V\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMOSFET Count:\u003c\/strong\u003e 8 MOS\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible Cells:\u003c\/strong\u003e 18650 Lithium-Ion\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eApplications:\u003c\/strong\u003e Angle grinder, chainsaw, electric wrench, power tool battery packs\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's in the Box?\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1× 21V 8-MOS Balance Protection Board\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWhether you're replacing a worn-out BMS in an existing battery pack or building a custom 18650 pack from scratch, this protection board is a smart, cost-effective solution for your workshop or DIY projects.\u003c\/p\u003e\n\n\u003cp\u003eFor guidance on safe handling of lithium-ion batteries and power tool safety, visit the U.S. Consumer Product Safety Commission (CPSC).\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: What is a 21V 8-MOS Balance Protection Board for 18650 batteries?\u003c\/h4\u003e\n\u003cp\u003eA: It is a Battery Management System (BMS) circuit board that protects and balances a 5-cell 18650 lithium-ion battery pack rated at 21V. The 8 MOSFET transistors manage overcharge, over-discharge, over-current, and short-circuit events, keeping your battery pack safe and your power tools performing at their best.\u003c\/p\u003e\n\u003ch4\u003eQ: Which power tools is this protection board compatible with?\u003c\/h4\u003e\n\u003cp\u003eA: This board is compatible with a wide range of 21V cordless power tools that use 18650 lithium-ion battery packs, including angle grinders, chainsaws, electric wrenches, drills, and similar DIY and workshop tools.\u003c\/p\u003e\n\u003ch4\u003eQ: Is this board suitable for DIY battery pack builds?\u003c\/h4\u003e\n\u003cp\u003eA: Yes — it is a popular choice for DIY enthusiasts who are repairing existing battery packs or assembling custom 18650 battery packs for power tools. The built-in balancing and multi-protection features make it a reliable component for custom cordless tool projects.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What is a 21V 8-MOS Balance Protection Board for 18650 batteries?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It is a Battery Management System (BMS) circuit board that protects and balances a 5-cell 18650 lithium-ion battery pack rated at 21V. 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