{"product_id":"caterpillar-s40-replacement-battery-38v-2900mah-li-polymer","title":"Cat S40 Smartphone Replacement Battery 3.8V 2900mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eCATERPILLAR S40 — 3.8V Li-Polymer Replacement Battery (458002-S40)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.8V, 2900mAh lithium-polymer battery is a direct cell replacement for the CATERPILLAR S40 rugged smartphone. It fits the S40's internal battery bay and reconnects to the phone's charge IC and fuel gauge circuit via the original flex connector. Capacity matches the factory spec at 11.02Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eS40 platform fit:\u003c\/strong\u003e\n    The S40 uses a fixed internal battery with a proprietary flex connector tied directly to the fuel gauge IC. This cell matches the voltage rail, physical dimensions (95.65 × 55.64 × 3.35mm), and connector pinout so the BMS handshake completes on first boot.\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 S40 platform. The BMS accepted the new cell without fault codes, and the coulomb counter initialised correctly after one complete cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map its reference curve against the new cell before high-current charging begins on an uncalibrated counter.\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 S40 after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC is still running the discharge curve from the old, degraded cell. The new cell has a steeper voltage cliff at low state-of-charge, so the phone hits the hardware undervoltage cutoff before the OS percentage reaches zero. The phone shuts down even though the reported figure looks safe. One full discharge-charge cycle recalibrates the coulomb counter to the new cell's actual curve and eliminates the early cutoff.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eOS reporting erratic or stuck battery percentage after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe S40's fuel gauge IC stores a learned model of the old cell's capacity and self-discharge rate in non-volatile memory. When a new cell goes in, that stored model no longer matches reality, so percentage readings jump, stall, or read 100% immediately after a short charge. Drain the phone fully until it shuts off, then charge uninterrupted to 100% without interruption. After that single full cycle the IC writes a new baseline and percentage reporting stabilises.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43392003735642,"sku":"BWCS-CAS400SL-1","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43392003768410,"sku":"BWCS-CAS400SL-2","price":28.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43392003801178,"sku":"BWCS-CAS400SL-3","price":31.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CAS400SL-1.webp?v=1779142903","url":"https:\/\/batteryweb.com\/products\/caterpillar-s40-replacement-battery-38v-2900mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}