{"product_id":"t-mobile-octopus-open-replacement-battery-36v-700mah-ni-mh","title":"T-Mobile 3BN78319 Octopus Open Cordless Phone Replacement Battery 3.6V 700mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eT-Mobile Octopus Open \/ Octophon Open 400 D — 3.6V Ni-MH Replacement Battery (3BN78319)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.6V, 700mAh Ni-MH pack replaces the original battery in the T-Mobile Octopus Open and Octophon Open 400 D cordless handsets. It matches the OEM voltage, capacity, and connector spec for a direct swap. Dimensions are 51.09 × 36.94 × 11.11mm — confirm fitment against your existing cell before installing.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOctopus Open and Octophon Open 400 D compatibility:\u003c\/strong\u003e\n    Both handsets run the same 3.6V NiMH cell with identical connector and physical format. OEM references 3BN78319, 3BN66305AAAA041030, 3BN66305AAAA000904, and ALCH-011644AC all cross to this pack.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through charge and discharge on a DECT handset rig. The BMS accepted standard base-station charge current without interruption and voltage held stable across the RF transmit window.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-charge protocol for NiMH cordless packs:\u003c\/strong\u003e\n    After installing, seat the handset in the base and leave it there for a full 16 hours before first use. NiMH cells shipped from storage need a slow, uninterrupted charge to reach rated capacity — a short first charge locks in reduced capacity from the start.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Octopus Open shows shorter talk time after a battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eNiMH cells don't deliver full rated capacity on the first cycle out of storage. The chemistry needs three to five full charge-discharge cycles before the cell reaches 700mAh. Running the handset until it cuts off and then charging fully in the base each time accelerates this break-in. Expect rated performance by cycle four or five.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBase station charge light stays off or shows an error after fitting the new pack\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eNiMH cells in storage drop below the voltage threshold that some DECT base stations require before accepting a charge. The base reads the resting voltage as a fault rather than a depleted cell. To recover, remove the battery, leave it at room temperature for 30 minutes, then reseat the handset firmly in the cradle. If the base still doesn't respond, check the cradle contacts are clean — oxidised contacts on 3.6V circuits cause the same symptom.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43340059639898,"sku":"BWCS-ALM100CL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43340059672666,"sku":"BWCS-ALM100CL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43340059705434,"sku":"BWCS-ALM100CL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-ALM100CL-1.webp?v=1778367023","url":"https:\/\/batteryweb.com\/products\/t-mobile-octopus-open-replacement-battery-36v-700mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}