{"product_id":"18v-lithium-battery-pcb-protection-board-bl1850b-bl1840b-1","title":"18V Li-ion Battery PCB Protection Board for BL1850B BL1840B","description":"\n\u003ch2\u003e18V Power Tool Lithium Battery PCB Protection Board with Indicator\u003c\/h2\u003e\n\u003cp\u003eKeep your 18V lithium battery packs running safely and efficiently with this high-performance PCB Protection Board. Engineered for compatibility with BL1850B, BL1840B, and similar 4.0Ah \/ 5.0Ah battery assemblies, this board delivers rock-solid cell-level monitoring and multi-layered safety cut-off functions — perfect for DIY battery rebuilds and power tool repairs.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Built-In IC Monitoring:\u003c\/strong\u003e Continuously tracks the voltage of every individual cell and logs usage cycles for smarter battery management.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFull Cell-Level Protection:\u003c\/strong\u003e Independent safeguards for each cell including overheat, overvoltage, undervoltage, overcurrent, and overload automatic cut-off.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLow Voltage Auto Shut-Off:\u003c\/strong\u003e Designed specifically for 18V power tool battery packs to prevent over-discharge damage during heavy use.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigh Shock Resistance:\u003c\/strong\u003e Reliable, stable performance under demanding conditions — an ideal match for electric torque wrenches, impact drills, and angle grinders.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eContinuous 60A Max Discharge:\u003c\/strong\u003e Supports pulse high current up to short-circuit protection threshold for demanding power tool applications.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilt-In Charge Indicator:\u003c\/strong\u003e Visual indicator lets you monitor battery status at a glance.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Green PCB\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRated High Discharge Rate\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e15A\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMax Discharge Current\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eContinuous 60A (pulse high current supported)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eTotal Discharge Cut-Off Voltage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e13.75V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSingle Cell Overcharge Protection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e4.25V ± 0.025V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSingle Cell Overcharge Recovery\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e4.1V ± 0.025V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSingle Cell Over-Discharge Protection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e2.7V ± 0.08V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSingle Cell Over-Discharge Recovery\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3.0V ± 0.08V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCharging High Temp Protection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eOver 60°C ± 2°C\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOvercurrent Protection 1\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e≥100A, 1s delay trigger\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOvercurrent Protection 2\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e≥180A, 100ms delay trigger\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eShort Circuit Protection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e≥200A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003ePre-Assembly Operation Guide\u003c\/h3\u003e\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNew Cell Assembly:\u003c\/strong\u003e Only high-rate power lithium cells are allowed. For 6-cell battery packs, match balance resistors and capacitors to equalize all cell voltages before assembly.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOld Battery Pack Repair:\u003c\/strong\u003e Test the voltage of every single cell. If voltages are inconsistent, charge each cell separately to reach a uniform voltage before soldering.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003cp\u003e\u003cstrong\u003e⚠️ Important:\u003c\/strong\u003e All battery cells must be balanced to the same voltage before soldering to the PCB board. Unbalanced cells may cause improper function or trigger safety cut-offs.\u003c\/p\u003e\n\n\u003ch3\u003ePackage Contents\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × 18V Lithium Battery PCB Protection Board\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: PCB board only. Batteries, cells, and other assembly components are not included.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003cp\u003eMade in Mainland China.\u003c\/p\u003e\n\n\u003ch3\u003eYou May Also Like\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/reptile-infrared-heat-lamp-bulb-terrarium-turtle-heater\"\u003eReptile Infrared Heat Lamp Bulb | Turtle \u0026amp; Terrarium Heater\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/usb-heated-shawl-blanket-3-gear-wearable-warm-wrap\"\u003eKesoto USB Heated Shawl Blanket – 3-Gear Wearable Warm Wrap\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/braided-cotton-candle-wick-spool-diy-candle-making\"\u003eBraided Cotton Candle Wick Spool – 32–98 Ft DIY Candle Making\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.epa.gov\/recycle\/used-lithium-ion-batteries\" target=\"_blank\" rel=\"noopener\"\u003eEPA guidance on lithium-ion battery handling\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: Is this PCB protection board compatible with Makita BL1850B and BL1840B battery packs?\u003c\/h4\u003e\n\u003cp\u003eA: Yes, this 18V lithium battery PCB protection board is designed to be compatible with BL1850B, BL1840B, and similar 18V 4.0Ah \/ 5.0Ah lithium battery pack assemblies commonly used in power tools. Always verify cell count and configuration before assembly.\u003c\/p\u003e\n\u003ch4\u003eQ: What protections does this PCB board provide for my battery cells?\u003c\/h4\u003e\n\u003cp\u003eA: This board provides comprehensive cell-level protection including overvoltage, undervoltage, overcurrent, overload, overheating (over 60°C), and short-circuit (≥200A threshold) automatic cut-off functions — independently monitored for each cell via dual built-in ICs.\u003c\/p\u003e\n\u003ch4\u003eQ: Do I need to balance the cells before soldering them to this PCB protection board?\u003c\/h4\u003e\n\u003cp\u003eA: Yes, this is critical. All battery cells must be charged and balanced to the same voltage before soldering to the PCB board. Unbalanced cells can cause errors in the protection circuitry. For old battery pack repairs, test and individually charge each cell to achieve uniform voltage prior to assembly.\u003c\/p\u003e\n\u003ch4\u003eQ: What types of power tools is this protection board suitable for?\u003c\/h4\u003e\n\u003cp\u003eA: This PCB board is ideally matched for use with electric torque wrenches, impact drills, angle grinders, and a wide range of other 18V power tool equipment that use compatible lithium battery packs.\u003c\/p\u003e\n\u003c!-- production-packaging-notice --\u003e\n\u003ch3\u003eProduction \u0026amp; Packaging Notice\u003c\/h3\u003e\n\u003cp\u003eTo maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Is this PCB protection board compatible with Makita BL1850B and BL1840B battery packs?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes, this 18V lithium battery PCB protection board is designed to be compatible with BL1850B, BL1840B, and similar 18V 4.0Ah \/ 5.0Ah lithium battery pack assemblies commonly used in power tools. 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