{"product_id":"huawei-u2801-replacement-battery-37v-950mah-li-ion","title":"Huawei Band 2 Pro HBU83S Compatible Battery 3.7V 950mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eHuawei Band 2 Pro U2801 Series — 3.7V Li-ion Replacement Battery (HBU83S)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 950mAh Li-ion cell replaces the HBU83S \/ HB4A1H battery in the Huawei Band 2 Pro fitness tracker. It fits the U2801, U2801-5, Envoy U3900, M318, and over a dozen other Huawei wearable and compact mobile models sharing the same footprint and connector. Dimensions are 53.78 × 34.05 × 4.80mm — measure the original cell before ordering if your unit isn't on the confirmed fit list.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eU2801 and Envoy U3900 platform fit:\u003c\/strong\u003e\n    These models share a common PCB connector pinout and cell cavity. The BMS on each device expects a 3.7V nominal cell with a charge ceiling at 4.2V — this cell meets both conditions without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through full charge and discharge on the U2801 platform. The onboard BMS accepted the cell without error flags, and charge current tapered correctly as voltage approached 4.2V.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    After installing this cell, run one complete discharge to automatic shutoff, then charge to 100% without interruption. The fuel gauge IC on these Huawei wearables calibrates its coulomb counter against that first full cycle — skipping it causes erratic percentage readings for weeks.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Band 2 Pro shuts off suddenly at 20–30% after a cell replacement\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe U2801 fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, the stored curve no longer matches actual cell voltage behaviour under sensor and display load. At roughly 3.6V, the new cell's voltage can sag below the shutdown threshold while the gauge still reads 20–30%. The fix is one full discharge-charge cycle with all sensors active — GPS, heart rate, and Bluetooth on — so the IC relearns the curve under real load conditions.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice won't power on after the replacement cell sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells in storage self-discharge slowly. If the cell voltage dropped below approximately 2.5V before installation, the BMS enters lockout mode and blocks current to protect the cell from an uncontrolled charge surge. The U2801 won't respond to the charge cable or the power button in this state. Connect the device to a 5V USB source and leave it for 20–30 minutes — the BMS on these Huawei boards includes a trickle pre-charge stage that will bring the cell back above the 2.7V reinitialisation threshold before switching to normal CC\/CV charging.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404313460826,"sku":"BWCS-HUM318XL-1","price":28.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404313493594,"sku":"BWCS-HUM318XL-2","price":32.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404313526362,"sku":"BWCS-HUM318XL-3","price":34.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-HUM318XL-1.webp?v=1779369680","url":"https:\/\/batteryweb.com\/products\/huawei-u2801-replacement-battery-37v-950mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}