{"product_id":"survey-equipment-replacement-battery-74v-2600mah-li-ion","title":"Survey 7.4V Li-ion Replacement Battery 29518 2600mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSurvey Equipment — 7.4V Li-ion Replacement Battery (29518 \/ EI-D-LI1)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 7.4V, 2600mAh Li-ion pack replaces the original battery in Survey portable field instruments cross-referencing OEM part numbers 29518, 38403, 46607, 52030, C8872A, and EI-D-LI1. It fits the compact 70.40 × 38.70 × 20.50mm bay used across this equipment series. Capacity is 19.24Wh, matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMulti-part-number platform compatibility:\u003c\/strong\u003e\n    Six OEM numbers cross to this single cell format because Survey used the same 7.4V two-cell arrangement and connector pinout across several instrument revisions — the BMS handshake protocol and physical housing remained unchanged between production runs.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through probe initialisation, sustained sensor logging, and USB data-transfer loads simultaneously. The BMS held voltage without tripping during combined-draw events, and cell balance stayed within 20mV across a full discharge cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePre-deployment calibration cycle:\u003c\/strong\u003e\n    After installing this pack, run a full calibration cycle through the instrument menu before heading to site. The instrument maps battery state during calibration, and skipping this step causes premature low-battery warnings during your first measurement session in the field.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBMS cutoff when a probe or sensor module initialises\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eWhen a probe powers up, the instrument draws a short current spike to initialise the sensor circuit. On an aged or partially discharged cell, that spike can pull the pack voltage below the BMS undervoltage threshold — typically around 6.0V for a 7.4V two-cell pack — triggering an immediate cutoff. The instrument interprets this as a dead battery even if the state of charge indicator read 40% a moment earlier. Charge the new pack to full before first use and confirm resting voltage sits above 8.0V before attaching the probe module.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eInstrument refuses to power on after the pack sat unused in a carry case for months\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells self-discharge at roughly 2–3% per month, and after extended storage the pack voltage can drop below the BMS recovery threshold — around 5.5V for this two-cell configuration — placing the BMS in sleep mode. The instrument sees no valid voltage signal and will not boot, which looks identical to a failed battery. Connect the pack to the original charger and leave it for at least 30 minutes without interruption; most chargers apply a trickle pre-charge current to recover cells in sleep mode. If the charger LED does not change state after 45 minutes, the cells have dropped below recoverable voltage — replace the pack rather than continuing to charge.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43360794280026,"sku":"BWCS-LI1XL-1","price":33.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43360794312794,"sku":"BWCS-LI1XL-2","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43360794345562,"sku":"BWCS-LI1XL-3","price":42.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-LI1XL-1.webp?v=1778616260","url":"https:\/\/batteryweb.com\/products\/survey-equipment-replacement-battery-74v-2600mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}