{"product_id":"tecpro-tw408-replacement-battery-37v-1800mah-li-polymer","title":"TECPRO TW408 Replacement Battery 3.7V 1800mAh Li-Polymer","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eTECPRO TW408 — 3.7V Li-Polymer Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 1800mAh Li-Polymer battery is a direct replacement for the TECPRO TW408 portable surveying and field measurement instrument. It fits the TW408's battery bay and matches the original cell's voltage and connector profile. Capacity is 1800mAh (6.66Wh), sourced to match the factory specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTW408 platform fit:\u003c\/strong\u003e\n    The TW408 runs a single-cell Li-Polymer architecture at 3.7V nominal. This pack matches that voltage rail and the BMS handshake threshold the instrument expects at power-on. Fitting a mismatched voltage cell causes the instrument to refuse boot or report a battery fault immediately.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through the TW408's probe initialisation sequence, which draws a short current spike as the sensor module powers up. The BMS handled that spike without tripping into protection mode, and the instrument continued into normal measurement operation without interruption.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install calibration cycle:\u003c\/strong\u003e\n    After fitting this battery, run a full calibration cycle through the TW408's instrument menu before field deployment. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during the first measurement session, even with a fully charged pack.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBMS lockout after the TW408 sat unused in a carry case for months\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eLi-Polymer cells self-discharge slowly over time. If the TW408 sat in storage long enough, the cell voltage drops below the BMS recovery threshold — typically around 2.5V for single-cell Li-Polymer packs. At that point the BMS latches into deep-discharge protection and the instrument will not power on or accept a charge. To recover, connect the charger and leave it for 20–30 minutes without expecting any charge indicator to appear immediately — the BMS needs a trickle current to exit lockout before normal charging resumes. If voltage has dropped below approximately 2.0V, the pack will not recover and must be replaced.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eTW408 display showing an inconsistent battery percentage after a reboot\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eWhen a new pack is installed, the TW408's voltage-threshold indicator has no baseline for the new cell and reads state-of-charge from a single static voltage sample at boot. This produces percentage jumps — the display may show 80% then drop to 55% within minutes of starting work. The fix is to run the instrument through one full charge-to-discharge-to-charge cycle so the indicator can anchor its thresholds to the new cell's actual discharge curve. After one complete cycle, the percentage readout stabilises and tracks correctly through subsequent field sessions.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43360621953114,"sku":"BWCS-NXL200SL-1","price":34.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43360621985882,"sku":"BWCS-NXL200SL-2","price":40.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43360622018650,"sku":"BWCS-NXL200SL-3","price":44.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NXL200SL-1.webp?v=1778616135","url":"https:\/\/batteryweb.com\/products\/tecpro-tw408-replacement-battery-37v-1800mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}