{"product_id":"retevis-rt81-replacement-battery-74v-2050mah-li-ion","title":"Retevis RT81 Replacement Battery BL50 7.4V 2050mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eRetevis RT81 \/ RT82 Series — 7.4V Li-ion Replacement Battery (BL50 \/ LB-75L)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.4V, 2050mAh lithium-ion battery that replaces the OEM BL50 and LB-75L packs on the Retevis RT81, RT82, RT81V, and RT50. It fits the same battery cavity and uses the same contact configuration as the original. Voltage and capacity match the factory spec exactly.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eRT81 \/ RT82 \/ RT81V \/ RT50 platform fit:\u003c\/strong\u003e\n    These models share the same 7.4V battery bay, contact strip layout, and BMS handshake protocol. One pack covers all four radios — no adapter or modification needed.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through PTT transmit loads on the RT81. The BMS handled the current spike on key-up without tripping, and the pack held voltage across sustained transmit without dropping below the radio's low-battery threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst insertion into the RT81 charger dock:\u003c\/strong\u003e\n    If the dock shows a fault or blinking LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The RT81 charger requires a clean contact cycle to complete the BMS handshake before it begins charging.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eRT81 cuts out mid-transmission on a new BL50 pack\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eNew lithium-ion cells ship at storage voltage — typically 3.6–3.7V per cell, not full charge. When the RT81 keys up, transmit current demand spikes sharply. If the pack is at storage voltage, that spike can pull cell voltage below the BMS overcurrent threshold and trigger a momentary cutoff, killing the transmission. This is not a faulty pack. Fully charge the battery in the dock before the first use — a complete charge cycle brings both cells to 4.2V and gives the BMS the headroom it needs to handle PTT surges cleanly.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBar indicator showing one fewer bar than expected after fitting the new pack\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe RT81 uses a voltage-threshold bar indicator — each bar corresponds to a voltage window, not a capacity percentage. A new pack at storage voltage sits in the two-bar window even though the cell is healthy. After a full charge cycle, resting voltage rises to approximately 8.3–8.4V across the pack, and the indicator moves to the correct full-charge bar level. If the indicator stays low after a full charge, check that the gold contacts on both the pack and the radio are clean — oxide buildup on the contacts causes a small voltage drop that shifts the reading down by one bar.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43426272772186,"sku":"BWCS-TMR380TW-1","price":51.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43426272804954,"sku":"BWCS-TMR380TW-2","price":59.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43426272837722,"sku":"BWCS-TMR380TW-3","price":67.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-TMR380TW-1.webp?v=1779930523","url":"https:\/\/batteryweb.com\/products\/retevis-rt81-replacement-battery-74v-2050mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}