{"product_id":"xtar-mc2-2-slot-battery-charger-1a-constant-current-usb-charger-for-18650-21700-26650-more-supports-protected-21700","title":"XTAR MC2 2-Slot Battery Charger – 1A Constant Current USB Charger for 18650, 21700, 26650 \u0026 More (Supports Protected 21700)","description":"\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"5:1-5:12;108-119\"\u003eOverview\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"7:1-7:421;121-541\"\u003eThe XTAR MC2 is a compact, two-slot USB charger for cylindrical lithium-ion cells, covering everything from small 10440s up to 26650s and protected 21700 cells. It charges both slots at a full 1A simultaneously — no current-splitting penalty for using both bays at once — and uses a 3-stage charging process (trickle, constant current, constant voltage) to bring cells to a full, stable charge without overcharging them.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"9:1-9:183;543-725\"\u003eIt's built for people who want a genuinely portable charger that doesn't force a trade-off between size and charge speed: small enough to carry in a bag, fast enough for regular use.\u003c\/p\u003e\n\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"11:1-11:14;727-740\"\u003eFull Specs\u003c\/h2\u003e\n\u003cdiv class=\"overflow-x-auto w-full px-2 mb-6\" data-sourcepos=\"13:1-29:104;742-1781\"\u003e\n\u003ctable class=\"min-w-full border-collapse text-sm leading-[1.7] whitespace-normal\"\u003e\n\u003cthead class=\"text-left\"\u003e\n\u003ctr\u003e\n\u003cth class=\"text-text-100 border-b-0.5 border-[hsl(var(--border-300)\/0.6)] py-2 pr-4 align-top font-bold\" scope=\"col\"\u003eParameter\u003c\/th\u003e\n\u003cth class=\"text-text-100 border-b-0.5 border-[hsl(var(--border-300)\/0.6)] py-2 pr-4 align-top font-bold\" scope=\"col\"\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003cbr\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eModel\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eMC2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eInput\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eType-C, 5V⎓2A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eCharging Current\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e1A per slot (both slots simultaneously — 1A x1 or 1A x2, not shared)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eCharging Method\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e3-stage: trickle charge → constant current → constant voltage\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eEnd-of-Charge Voltage\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e4.2V ±0.05V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eEnd-of-Charge Current\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e\u0026lt;130mA cutoff\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e0°C to 40°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eDimensions\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eL103mm x W53mm x H30mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eWeight\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e54g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eCompatible Chemistry\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e3.6V\/3.7V lithium-ion (Li-ion\/IMR\/INR\/ICR)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eCompatible Cell Sizes\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e10440, 14500, 14650, 16340, 17335, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eProtected Cell Support\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eYes — supports protected 21700 cells\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eSpecial Feature\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003e\"0V\" activation technology for recovering some over-discharged cells\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eStatus Indicators\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eGreen = standby or fully charged; Red = actively charging; Off\/unlit = reverse polarity or abnormal insertion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eSafety Protections\u003c\/td\u003e\n\u003ctd class=\"border-b-0.5 border-[hsl(var(--border-300)\/0.3)] py-2 pr-4 align-top\"\u003eReverse polarity protection, short-circuit protection, automatic charge cutoff\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003cbr\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"31:1-31:43;1783-1825\"\u003eHow the Charging Process Actually Works\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"33:1-33:97;1827-1923\"\u003eThe MC2 doesn't just dump current into a cell and stop — it moves through three distinct stages:\u003c\/p\u003e\n\u003col class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-decimal flex flex-col gap-1 pl-8 mb-3\" data-sourcepos=\"35:1-37:213;1925-2475\"\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"35:1-35:143;1925-2067\"\u003e\n\u003cstrong\u003eTrickle charge\u003c\/strong\u003e — a small preliminary current tops off and, where applicable, helps activate a deeply discharged cell before ramping up.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"36:1-36:195;2068-2262\"\u003e\n\u003cstrong\u003eConstant current\u003c\/strong\u003e — the charger increases and holds a steady current while the cell's voltage climbs; this is where most of the capacity gets restored, and it's the fastest-charging phase.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"37:1-37:213;2263-2475\"\u003e\n\u003cstrong\u003eConstant voltage\u003c\/strong\u003e — as the cell approaches full charge, the charger holds voltage steady and gradually reduces current, topping off the last portion of capacity without pushing the cell past a safe voltage.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"39:1-39:203;2477-2679\"\u003eThis is standard, sound practice for lithium-ion charging — it's what protects cell longevity better than a charger that just charges at a flat current until it hits a voltage cutoff and stops abruptly.\u003c\/p\u003e\n\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"41:1-41:45;2681-2725\"\u003eWhat Makes This Charger Worth Considering\u003c\/h2\u003e\n\u003cul class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\" data-sourcepos=\"43:1-46:246;2727-3906\"\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"43:1-43:297;2727-3023\"\u003e\n\u003cstrong\u003eReal 1A per slot, no splitting\u003c\/strong\u003e — plenty of basic dual-slot chargers cut each slot's current in half when both bays are occupied. The MC2 doesn't do that: each slot gets a full 1A regardless of whether the other is in use, so a typical 18650 charges in a few hours rather than most of a day.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"44:1-44:411;3024-3434\"\u003e\n\u003cstrong\u003e0V activation\u003c\/strong\u003e — most basic chargers simply refuse to recognize a cell that's been discharged too far below its normal cutoff voltage. The MC2's activation function can attempt a slow, controlled recovery charge on some of these cells rather than treating them as dead on arrival. It won't save every over-discharged cell — some genuinely are beyond recovery — but it gives borderline cells a real chance.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"45:1-45:226;3435-3660\"\u003e\n\u003cstrong\u003eBroad size compatibility\u003c\/strong\u003e — from small 10440s (common in flashlights and ) up through 26650s, plus protected 21700 cells, this one charger covers most of the cylindrical lithium-ion formats you're likely to own.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"46:1-46:246;3661-3906\"\u003e\n\u003cstrong\u003eSimple status reporting\u003c\/strong\u003e — the LED colors are unambiguous: green means it's either standing by or done, red means it's actively working, and no light at all is the charger telling you something's inserted wrong before it does anything else.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"48:1-48:24;3908-3931\"\u003eWhat to Keep in Mind\u003c\/h2\u003e\n\u003cul class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\" data-sourcepos=\"50:1-52:190;3933-4680\"\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"50:1-50:368;3933-4300\"\u003e\n\u003cstrong\u003eThis charges bare cells only in the sense that it doesn't manage discharge-side protection.\u003c\/strong\u003e The MC2 handles charging safely (voltage\/current cutoffs, reverse polarity, short circuit), but if you're using unprotected cells in a device, that device still needs its own low-voltage cutoff — the charger's protections don't extend to how the cell is used afterward.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"51:1-51:190;4301-4490\"\u003e\n\u003cstrong\u003eOperating temperature matters.\u003c\/strong\u003e Charging outside the 0-40°C range isn't something this charger is rated to handle safely — keep it somewhere reasonable, not in direct sun or a hot car.\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body whitespace-normal break-words pl-2\" data-sourcepos=\"52:1-52:190;4491-4680\"\u003e\n\u003cstrong\u003eTwo different cell sizes at once is fine.\u003c\/strong\u003e Because the slots operate independently with automatic detection, you can charge, say, one 18650 and one 21700 side by side without an issue.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\" data-sourcepos=\"54:1-54:30;4682-4711\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"56:1-57:243;4713-5014\"\u003e\u003cstrong\u003eQ: How long does it take to fully charge a typical 18650?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"56:1-57:243;4713-5014\"\u003eA: At a full 1A, a 2,500-3,000mAh 18650 typically reaches full charge in roughly 3-4 hours, accounting for the tapering constant-voltage stage near the end. Larger cells (21700, 26650) will take proportionally longer given their higher capacity.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"59:1-60:122;5016-5195\"\u003e\u003cstrong\u003eQ:Does charging two cells at once slow either one down?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"59:1-60:122;5016-5195\"\u003eA: No. Each slot delivers its own full 1A independently — you're not splitting a shared current budget between the two bays.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"62:1-63:196;5197-5429\"\u003e\u003cstrong\u003eQ: Can this charge protected cells?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"62:1-63:196;5197-5429\"\u003eA: Yes, it supports protected 21700 cells. For other protected cell sizes, check the cell's own spec sheet — protection circuits vary and some add length that may not fit every charger's slot depth.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"65:1-66:164;5431-5657\"\u003e\u003cstrong\u003eQ: What does it mean if a slot's LED doesn't light up at all?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"65:1-66:164;5431-5657\"\u003eA: That typically indicates a reverse-polarity insertion or another abnormal condition the charger has detected. Remove the cell, check its orientation, and reinsert.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"68:1-69:277;5659-5997\"\u003e\u003cstrong\u003eQ: Is the \"0V activation\" feature safe to rely on regularly?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal\" data-sourcepos=\"68:1-69:277;5659-5997\"\u003eA: It's meant as a recovery option for occasional over-discharge situations, not a substitute for storing and using cells properly in the first place. A cell that repeatedly needs 0V activation is showing signs of wear or misuse and is worth watching more closely — or replacing.\u003c\/p\u003e","brand":"XTAR","offers":[{"title":"Default Title","offer_id":51454215454966,"sku":"OAS1368","price":14.98,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0819\/2753\/6886\/files\/xtar-mc2-main-hero-2slot-charger_815327cb-3adf-4636-b836-db407092465e.webp?v=1786968308","url":"https:\/\/oneandes.com\/products\/xtar-mc2-2-slot-battery-charger-1a-constant-current-usb-charger-for-18650-21700-26650-more-supports-protected-21700","provider":"OneAndes","version":"1.0","type":"link"}