{"product_id":"fitage-katharina-das-grobe-replacement-battery-37v-1400mah-li-polymer","title":"Fitage Katharina das Grobe 3.7V Replacement Battery 1400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFitage Katharina das Grobe — 3.7V Li-Polymer Replacement Battery (VKB 66591 312 098)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1400mAh Li-Polymer replacement battery for the Fitage Katharina das Grobe smartphone. It replaces part number VKB 66591 312 098 directly. Capacity is 1400mAh (5.18Wh), matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eKatharina das Grobe fit:\u003c\/strong\u003e\n    This cell matches the voltage rail, physical footprint (41.23 × 33.48 × 8.90mm), and connector orientation of the Katharina das Grobe. The BMS handshake expects a 3.7V nominal Li-Polymer cell — any deviation trips the charge IC and blocks recognition.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on a Katharina das Grobe unit. The BMS accepted the cell without error codes, charge termination triggered correctly at 4.2V, and the fuel gauge IC updated state-of-charge readings within the first full cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fuel gauge reset:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current fast charging pushes current into an uncalibrated cell.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% on the Katharina das Grobe after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eA new Li-Polymer cell has a slightly different discharge curve than the aged cell the fuel gauge IC was originally calibrated against. When the phone hits a load spike — from the modem, screen backlight, or GPS — the cell voltage drops sharply below the BMS cutoff threshold even though the reported percentage still shows 20–30%. The phone shuts down to protect the cell. One full discharge-to-near-shutdown followed by a complete charge cycle resets the coulomb counter and aligns the fuel gauge to the new cell curve. After that cycle, shutdowns at high percentages typically stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice not powering on after the replacement cell sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-Polymer cells self-discharge in storage, and if the Katharina das Grobe battery dropped below approximately 2.5V per cell, the BMS enters a deep-discharge lockout state and blocks normal charging to prevent thermal runaway. The phone will show nothing — no charge indicator, no boot screen. Connect the phone to a low-current charger (5V\/0.5A or a standard USB wall adapter, not a fast charger) and leave it for 30–60 minutes without interrupting. The BMS uses a trickle pre-charge path at reduced current to bring the cell back above the 3.0V re-enable threshold before handing off to normal CC\/CV charging. Once the charge LED or on-screen indicator activates, normal charging has resumed.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405050904666,"sku":"BWCS-FBE003SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405050937434,"sku":"BWCS-FBE003SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405050970202,"sku":"BWCS-FBE003SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-FBE003SL-1.webp?v=1779369882","url":"https:\/\/batteryweb.com\/products\/fitage-katharina-das-grobe-replacement-battery-37v-1400mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}