{"product_id":"21700-bms-protection-circuit-board-21v-power-tool-battery-pcb","title":"21700 BMS Protection Circuit Board for 21V Power Tool Batteries","description":"\n\u003ch2\u003e21700 Lithium Battery BMS Protection Circuit Board – 21V Power Tools\u003c\/h2\u003e\n\u003cp\u003eKeep your cordless power tools running safely and efficiently with this high-quality \u003cstrong\u003eBattery Management System (BMS) Protection Circuit Board\u003c\/strong\u003e, designed specifically for \u003cstrong\u003e21700 lithium battery packs\u003c\/strong\u003e used in 21V power tools. Compatible with brands such as Lomvum, Zhipu, and Hongsong, this PCB replacement board helps safeguard your battery pack against overcharge, over-discharge, and short-circuit conditions — extending the working life of your tools and batteries.\u003c\/p\u003e\n\n\u003cp\u003eMade in Mainland China.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePurpose-Built BMS:\u003c\/strong\u003e Designed for 21700 lithium cell configurations in 21V cordless power tool battery packs.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCE Certified:\u003c\/strong\u003e Meets CE safety standards for electrical components.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOvercurrent \u0026amp; Short-Circuit Protection:\u003c\/strong\u003e Integrated protection circuits help prevent damage from electrical faults.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOver-Charge \u0026amp; Over-Discharge Protection:\u003c\/strong\u003e Helps maintain optimal battery cell health over time.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact PCB Size:\u003c\/strong\u003e Measures approximately 98 × 60 mm (3.86 × 2.36 in) — fits neatly into compatible tool battery housings.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDIY \u0026amp; Repair Friendly:\u003c\/strong\u003e Ideal for electronics hobbyists and tool repair technicians rebuilding battery packs.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand New:\u003c\/strong\u003e Each board is new and quality-checked before shipment.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e PCB (Printed Circuit Board)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 98 × 60 mm \/ 3.86 × 2.36 in\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible Battery Type:\u003c\/strong\u003e 21700 Lithium\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible Voltage:\u003c\/strong\u003e 21V\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCertification:\u003c\/strong\u003e CE\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOrigin:\u003c\/strong\u003e Mainland China\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePackage Includes:\u003c\/strong\u003e 1 × BMS Protection Circuit Board\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eImportant Notes\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003ePhotos may not reflect the actual size — please refer to the dimensions listed above.\u003c\/li\u003e\n  \u003cli\u003eAllow ±5–10 mm variance due to manual measurement.\u003c\/li\u003e\n  \u003cli\u003eActual color may vary slightly from images due to monitor settings and lighting.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement part, not an OEM original board.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Products You May Like\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/electromagnetic-induction-tester-coil-motherboard-fault-detector\"\u003eElectromagnetic Induction Tester – Coil \u0026amp; Circuit Fault Detector\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/air-compressor-pressure-gauge-0-10-0-12-0-25-bar-hydraulic-diy\"\u003eAir Compressor Pressure Gauge 0-10\/0-12\/0-25 Bar | DIY Tool\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.energystar.gov\/products\" target=\"_blank\" rel=\"noopener\"\u003eENERGY STAR product efficiency guidance\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: Which power tool brands is this BMS protection circuit board compatible with?\u003c\/h4\u003e\n\u003cp\u003eA: This 21V BMS protection circuit board is designed to be compatible with 21700 lithium battery packs used in Lomvum, Zhipu, and Hongsong brand power tools. Always verify the dimensions (98 × 60 mm) and cell configuration of your existing battery pack before installing.\u003c\/p\u003e\n\u003ch4\u003eQ: What does the BMS (Battery Management System) protection circuit board do?\u003c\/h4\u003e\n\u003cp\u003eA: The BMS protection circuit board monitors and manages the 21700 lithium battery cells in your power tool battery pack. It provides overcharge protection, over-discharge protection, overcurrent protection, and short-circuit protection — helping to maintain safe operation and extend overall battery lifespan.\u003c\/p\u003e\n\u003ch4\u003eQ: Is this an original OEM board or an aftermarket replacement?\u003c\/h4\u003e\n\u003cp\u003eA: This is a brand-new aftermarket (non-original) replacement BMS protection circuit board. It is not an OEM part but is built to perform the same protection functions for compatible 21V lithium battery packs.\u003c\/p\u003e\n\u003ch4\u003eQ: What tools or skills do I need to install this circuit board?\u003c\/h4\u003e\n\u003cp\u003eA: Installation requires basic electronics knowledge, including the ability to solder connections and safely handle lithium battery cells. This board is best suited for experienced DIY electronics enthusiasts or professional battery repair technicians.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Which power tool brands is this BMS protection circuit board compatible with?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"This 21V BMS protection circuit board is designed to be compatible with 21700 lithium battery packs used in Lomvum, Zhipu, and Hongsong brand power tools. 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