{"product_id":"the-cell-keeper-5a-active-battery-balancer","title":"The Cell Keeper | 5A Active Balancer for LiFePO4, LiPo and LTO Packs","description":"\u003cdiv class=\"product-narrative\"\u003e\n\u003cp\u003e\u003cstrong\u003eA battery pack is only as strong as its weakest cell, and the weakest cell gets weaker every cycle.\u003c\/strong\u003e Capacity decays at slightly different rates across a pack, and once the spread widens the BMS starts reading a single low cell as a whole-pack problem. It cuts in early on charge, cuts out early on discharge, and the usable capacity of a pack you already paid for shrinks month by month.\u003c\/p\u003e\n\u003cp\u003eThe Cell Keeper attacks that drift directly. It is an active equaliser rather than a passive bleed resistor, so charge is transferred from the higher cells into the lower ones through a capacitor bank instead of being burned off as heat. Balance current runs from 0 up to 5.5A, and it drops as the pack approaches balance, which is the behaviour you want: fast correction when the spread is wide, gentle correction when the cells are close. Accuracy is held within 5 millivolts.\u003c\/p\u003e\n\u003cp\u003eCoverage runs from 3S to 17S in the standard editions, with a 10S to 24S smart edition rated at 4A for larger packs, and the working range of 1.8V to 4.5V per cell covers ternary lithium, lithium iron phosphate and lithium titanate. Editions marked LTO are for lithium titanate packs only, while unmarked editions suit ternary lithium and LiFePO4. Recommended pack capacity is 60 to 300Ah. A manual sleep switch and under-voltage sleep protection both cut standby draw below 0.1mA, so a stored pack does not flatten itself while it waits.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eBalancing will not add capacity to a pack. It stops you losing the capacity you already bought.\u003c\/em\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003chr style=\"margin:24px 0;border:0;border-top:1px solid #ececec;\"\u003e\n\u003cdiv class=\"product-features\"\u003e\n\u003ch3\u003eHow Active Balancing Works\u003c\/h3\u003e\n\u003cul style=\"list-style:none;padding:0;margin:0;\"\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Active capacitor energy transfer instead of heat-burning passive bleed\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Balance current from 0 to 5.5A, reducing automatically as the pack approaches balance\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Balance voltage accuracy held within 5 millivolts\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Coverage from 3S to 17S, plus a 10S to 24S smart edition rated at 4A\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Working range of 1.8V to 4.5V per cell for ternary lithium, LiFePO4 and LTO\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Ultra-low internal resistance MOS on a 2OZ copper PCB\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Manual sleep switch and under-voltage sleep protection below 3.0V, standby under 0.1mA\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e✦ Recommended for packs of 60 to 300Ah, CE certified\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"product-specs\"\u003e\n\u003ch3\u003eElectrical And Build Details\u003c\/h3\u003e\n\u003cul style=\"list-style:none;padding:0;margin:0;\"\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Active battery balancer, capacitor energy transfer\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eBalance current:\u003c\/strong\u003e 0 to 5.5A, self-reducing toward balance\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eBalance accuracy:\u003c\/strong\u003e Within 5mV\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eCoverage:\u003c\/strong\u003e 3S to 17S standard, 10S to 24S smart edition at 4A\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eWorking voltage:\u003c\/strong\u003e 1.8V to 4.5V per cell\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eBattery chemistries:\u003c\/strong\u003e Ternary lithium, LiFePO4, LTO (LTO editions for lithium titanate only)\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eRecommended pack capacity:\u003c\/strong\u003e 60 to 300Ah\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eQuiescent current:\u003c\/strong\u003e About 12mA\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eSleep current:\u003c\/strong\u003e Under 0.1mA with manual sleep switch\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eUnder-voltage protection:\u003c\/strong\u003e Sleeps below 3.0V, standby under 0.1mA\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eBoard:\u003c\/strong\u003e 2OZ copper thickness, ultra-low internal resistance MOS\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eCertification:\u003c\/strong\u003e CE\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eBattery included:\u003c\/strong\u003e No\u003c\/li\u003e\n\u003cli style=\"padding:9px 0;border-bottom:1px solid #f4f4f4;\"\u003e\n\u003cstrong\u003eCharger included:\u003c\/strong\u003e No\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"product-applications\"\u003e\n\u003ch3\u003eWhere Pack Drift Costs Real Money\u003c\/h3\u003e\n\u003cp\u003eThe Cell Keeper is fitted by people running packs that cost real money to replace. A solar or off-grid bank of lithium iron phosphate cells benefits most, because those packs are expected to last a decade and small drift compounds across that time. Electric bike, scooter and golf cart owners use it where a replacement pack is hundreds of dollars. Diy pack builders fit it from the start rather than discovering imbalance later. In each case the arithmetic is straightforward: the balancer costs a fraction of the cells it protects, and the pack keeps delivering the capacity it was specified for.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"product-faq\"\u003e\n\u003ch3\u003eMatching A Balancer To A Pack\u003c\/h3\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What is the difference between active balancing and a conventional BMS?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA conventional BMS often balances passively, burning excess charge from high cells as heat. This unit moves that charge into the lower cells by capacitor transfer, so the energy stays in the pack and the correction is faster.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Which edition do I need for my pack?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eMatch the series count first: 3-4S, 6-8S, 12-16S and 17-21S cover the standard list, and the Smart 10-24S edition at 4A covers larger packs. Then check the chemistry note, because editions marked LTO are for lithium titanate only.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Which chemistries are supported?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eTernary lithium, lithium iron phosphate and lithium titanate, working across 1.8V to 4.5V per cell. Unmarked editions suit ternary lithium and LiFePO4.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Will it drain my pack when the vehicle is parked?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. The manual sleep switch and the under-voltage sleep protection both drop current below 0.1mA when the balancer is idle.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How large a pack can it serve?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003ePacks of 60 to 300Ah are recommended. The balance current is sized for correction, not for charging, so the pack's own charger still does the charging.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-bottom:16px;\"\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Does the balance current stay at 5A all the time?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt reduces as the cells converge. The closer the pack is to balance, the smaller the current, which keeps the process gentle on cells that are already close.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"product-gallery\" style=\"margin-top:30px;text-align:center;\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S9eeb3f6d07ab467aaa12010126b18beeX_c9fc66e6-8b95-4d6e-80ee-491b90396617.webp?v=1\u0026amp;width=1200\" alt=\"5A active battery balancer for LiFePO4, LiPo and LTO packs\" style=\"max-width:100%;height:auto;margin:8px 0;border-radius:4px;\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0503\/6412\/1244\/files\/S806f9904a7b042a1b432900746b1a10aY_9dd9b37e-ecbe-4c5f-b111-ac202dfca73a.webp?v=1\u0026amp;width=1200\" alt=\"5A active battery balancer for LiFePO4, LiPo and LTO packs\" style=\"max-width:100%;height:auto;margin:8px 0;border-radius:4px;\"\u003e\n\u003cimg 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