{"product_id":"dejavoo-qd2-replacement-battery-74v-3400mah-li-ion","title":"Dejavoo QD2 Payment Terminal Replacement Battery 7.4V 3400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eDejavoo QD2 \/ QD4 — 7.4V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 7.4V, 3400mAh (25.16Wh) Li-ion battery fits the Dejavoo QD2 and QD4 mobile payment terminals. Both models share the same battery bay, connector, and BMS communication protocol, so one cell covers both units. Capacity is sourced from product data — 3400mAh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eQD2 and QD4 shared battery platform:\u003c\/strong\u003e\n    Both terminals run the same 7.4V voltage rail, use an identical physical connector, and expect the same BMS handshake on power-up. Swapping between units requires no adapters or firmware changes.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through full boot cycles on both the QD2 and QD4. The BMS handshake completed without fault codes, the charge IC entered normal top-off mode, and the terminal accepted the cell without prompting a battery error screen.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst transaction cycle after install:\u003c\/strong\u003e\n    Complete one full transaction — print a receipt, process a card — before deploying in a live environment. The QD2 maps battery capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator correctly.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eTerminal rebooting mid-transaction after battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe QD2's receipt printer draws a sharp current spike the moment it fires — often 1.5A or more above idle draw. On a new cell that hasn't completed a full charge cycle, the BMS can interpret that spike as an overcurrent event and cut power to protect the cell. This trips a hard reboot, which looks like a software crash but isn't. The fix is straightforward: charge the battery to full before first use, then run several complete transaction cycles including receipt printing. Once the BMS has logged normal load patterns, nuisance trips stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eQD2 won't power on after sitting unused in a drawer\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells self-discharge during storage. If the QD2 sits unused for several weeks or months, the cell can drop below the BMS recovery threshold — typically around 2.5V per cell — and the terminal will show no response at all when you press the power button. Connect the terminal to its original charger and leave it for 30–45 minutes without pressing anything. Most BMS circuits include a trickle-recovery mode that slowly brings the cell voltage back above the reinitialisation threshold. Once the charge LED activates normally, charge to full before powering on — target a full indicator before booting.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43415924670554,"sku":"BWCS-NEX800BX-1","price":49.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43415924703322,"sku":"BWCS-NEX800BX-2","price":58.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43415924736090,"sku":"BWCS-NEX800BX-3","price":64.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NEX800BX-1.webp?v=1779757951","url":"https:\/\/batteryweb.com\/products\/dejavoo-qd2-replacement-battery-74v-3400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}