{"product_id":"luneau-retinomax-iii-k-replacement-battery-74v-2600mah-li-ion","title":"Luneau Retinomax III K+ 7.4V 2600mAh Replacement Battery","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eLUNEAU Retinomax III K+ — 7.4V Li-ion Replacement Battery (88889045)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.4V 2600mAh Li-ion battery for the LUNEAU Retinomax III K+ portable autorefractor. It replaces OEM part 88889045 and fits directly into the Retinomax III K+ instrument used for refractive error measurement in clinical settings. Capacity figure is taken from verified product data: 2600mAh \/ 19.24Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eRetinomax III K+ platform fit:\u003c\/strong\u003e\n    The Retinomax III K+ uses a specific battery bay geometry and a 7.4V nominal rail matched to the instrument's measurement and display circuitry. This cell replicates the voltage, physical dimensions (71.70 × 37.60 × 20.40mm), and connector orientation of the original — the BMS handshake proceeds without triggering a battery-type mismatch fault.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through charge acceptance and discharge load profiling on the Retinomax III K+ platform. The BMS recognised the cell, completed its verification pass, and the instrument cleared its internal battery status flag without manual intervention.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap self-test protocol:\u003c\/strong\u003e\n    After installing this battery, allow the Retinomax III K+ to complete its full power-on self-test cycle without interruption. The device runs BMS verification at startup — cutting power during this sequence logs a false battery fault that persists until the next clean reboot.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Retinomax III K+ alarms low battery immediately after a confirmed full charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Retinomax III K+ BMS is calibrated against the charge profile of an aged OEM cell. A fresh cell presents a slightly different internal resistance signature on the first cycle, which the BMS can misread as a degraded pack. This triggers the low-battery alarm even when the cell is fully charged. One complete charge-discharge cycle recalibrates the BMS threshold to the new cell's profile. After that first cycle, the alarm clears and the capacity indicator reads accurately.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice fails to power on after the replacement cell sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells self-discharge in storage. If the replacement battery has been stored for several months, its resting voltage may have dropped below the Retinomax III K+'s BMS recovery threshold — typically around 2.5V per cell, or approximately 5.0V at pack level. When voltage falls below that floor, the BMS enters a locked state and refuses to output current, so the device shows no response at all. Connect the battery to its charger and leave it for a full charge cycle; most BMS circuits include a trickle pre-charge stage that recovers cells down to around 2.0V per cell before switching to normal charge rate.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381445066842,"sku":"BWCS-RTK300MD-1","price":35.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381445099610,"sku":"BWCS-RTK300MD-2","price":41.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381445132378,"sku":"BWCS-RTK300MD-3","price":45.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-RTK300MD-1.webp?v=1778900853","url":"https:\/\/batteryweb.com\/products\/luneau-retinomax-iii-k-replacement-battery-74v-2600mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}