{"product_id":"cisco-cp-7921-replacement-battery-37v-2000mah-li-polymer","title":"Cisco CP-7921 Replacement Battery 3.7V 2000mAh 74-4957-01","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eCisco CP-7921G Unified — 3.7V Li-Polymer Replacement Battery (74-4957-01)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 2000mAh lithium-polymer battery replaces the OEM pack in the Cisco CP-7921, CP-7921G, and CP-7921G Unified wireless IP handsets. It slots into the same battery bay and connects via the original latch cover. Capacity matches the product data at 7.4Wh — no spec inflation.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCP-7921 and CP-7921G compatibility:\u003c\/strong\u003e\n    All three variants — CP-7921, CP-7921G, and CP-7921G Unified — share the same battery bay geometry, connector pitch, and 3.7V rail. One pack covers the full range.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack on a CP-7921G unit, confirming the BMS holds charge acceptance through the handset's internal charge controller without triggering a fault LED on the base station.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-charge protocol for Li-Polymer IP handsets:\u003c\/strong\u003e\n    The CP-7921G uses a trickle-charge circuit in the base that tops the Li-Polymer pack slowly. Seat the handset in the base immediately after install and leave it undisturbed for a full charge cycle before pulling it into active use — this lets the BMS calibrate its state-of-charge registers correctly.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the CP-7921G base station shows a charge fault after a battery swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eA replacement Li-Polymer pack sitting in a warehouse often arrives at a storage voltage around 3.5V or lower. The CP-7921G base checks the pack voltage before enabling its charge circuit — if the pack reads below the acceptance threshold, the base logs a fault and stops charging. This is a protection feature, not a defect. Seating the handset, waiting 60 seconds, then reseating it gives the base controller a second handshake attempt, which usually clears the fault once it detects a valid cell voltage. If the fault persists, leave the handset seated for 15 minutes — the trickle pre-charge will pull the pack voltage up to the acceptance window.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eHandset loses DECT pairing after battery replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eRemoving the original battery cuts power to the CP-7921G's volatile memory, which can drop the stored DECT pairing data. This is a known behaviour on this handset — not a fault with the replacement battery. Re-register the handset to the Cisco Unified Communications Manager via the Settings menu under Network Configuration. Once re-registered, the handset pairs normally and holds the pairing across subsequent battery swaps as long as the new pack stays above 3.0V during storage.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43339892883546,"sku":"BWCS-CIP922CL-1","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43339892916314,"sku":"BWCS-CIP922CL-2","price":31.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43339892949082,"sku":"BWCS-CIP922CL-3","price":34.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CIP922CL-1.webp?v=1778366906","url":"https:\/\/batteryweb.com\/products\/cisco-cp-7921-replacement-battery-37v-2000mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}