{"product_id":"5s-bms-20a-li-ion-battery-protection-board-18v-21v-power-tools","title":"5S BMS 20A Li-Ion Battery Protection Board 18V–21V for Power Tools","description":"\u003ch2\u003e5S BMS 20A Li-Ion Battery Protection Board — 18V–21V Power Tool Packs\u003c\/h2\u003e\u003cp\u003eThis \u003cstrong\u003e5S BMS (Battery Management System)\u003c\/strong\u003e protection board is designed for \u003cstrong\u003e5-cell series Li-ion battery packs\u003c\/strong\u003e (18V nominal, 21V fully charged) used in power tools. It provides comprehensive protection including overcharge, over-discharge, overcurrent, and short-circuit protection, plus passive cell balancing to extend pack life.\u003c\/p\u003e\u003ch3\u003eKey Specifications\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCell Configuration\u003c\/td\u003e\n\u003ctd\u003e5S (5 cells in series)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNominal Voltage\u003c\/td\u003e\n\u003ctd\u003e18V (5 × 3.6V)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFull Charge Voltage\u003c\/td\u003e\n\u003ctd\u003e21V (5 × 4.2V)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eContinuous Discharge Current\u003c\/td\u003e\n\u003ctd\u003e20A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePeak Discharge Current\u003c\/td\u003e\n\u003ctd\u003e40A (short burst)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOvercharge Protection\u003c\/td\u003e\n\u003ctd\u003e4.25V ±0.05V per cell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOver-Discharge Protection\u003c\/td\u003e\n\u003ctd\u003e2.5V ±0.1V per cell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOvercurrent Protection\u003c\/td\u003e\n\u003ctd\u003e~25A (adjustable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eShort-Circuit Protection\u003c\/td\u003e\n\u003ctd\u003eYes — auto-recovery\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCell Balancing\u003c\/td\u003e\n\u003ctd\u003ePassive (during charging)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e−40°C to +85°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003eWhy Choose This 5S BMS?\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull Protection Suite\u003c\/strong\u003e — Overcharge, over-discharge, overcurrent, and short-circuit in one board\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePassive Cell Balancing\u003c\/strong\u003e — Equalizes cell voltages during charging to maximize capacity and cycle life\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e20A Continuous\u003c\/strong\u003e — Handles high-drain power tool loads (drills, saws, grinders)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAuto-Recovery\u003c\/strong\u003e — Automatically resets after short-circuit or over-discharge condition clears\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWide Temperature Range\u003c\/strong\u003e — −40°C to +85°C for demanding tool environments\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eTypical Applications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e18V power tool battery pack rebuild (Makita, DeWalt, Bosch compatible packs)\u003c\/li\u003e\n\u003cli\u003eDIY 5S Li-ion e-bike battery protection\u003c\/li\u003e\n\u003cli\u003e5S LiPo battery management for RC vehicles\u003c\/li\u003e\n\u003cli\u003e18V cordless tool battery replacement BMS\u003c\/li\u003e\n\u003cli\u003eCustom 18V battery pack for robotics and automation\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eWiring Guide\u003c\/h3\u003e\u003cp\u003eConnect B− to battery pack negative. Connect B1–B4 balance wires to cell junctions (between each cell). Connect P− to load\/charger negative. B+ and P+ share the pack positive terminal.\u003c\/p\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eQ: Is this BMS compatible with 18650 cells?\u003c\/strong\u003e\u003cbr\u003eA: Yes — designed for 5× 18650 Li-ion cells in series (or equivalent Li-ion chemistry at 3.6V\/4.2V per cell).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Can I use this BMS for charging and discharging simultaneously?\u003c\/strong\u003e\u003cbr\u003eA: This is a common-port BMS — charge and discharge share the same P+\/P− terminals. Simultaneous charge\/discharge is not recommended.\u003c\/p\u003e\u003ch3\u003ePackage Contents\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e1× 5S 20A Li-Ion BMS Protection Board\u003c\/li\u003e\u003c\/ul\u003e","brand":"Keszoox","offers":[{"title":"Default Title","offer_id":46991486746859,"sku":"\u003cnone\u003e","price":12.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/1005\/8731\/files\/battery-protection-bms-5s.webp?v=1761538910","url":"https:\/\/keszoox.com\/products\/5s-bms-20a-li-ion-battery-protection-board-18v-21v-power-tools","provider":"Keszoox","version":"1.0","type":"link"}