{"product_id":"drager-pss-merlin-replacement-battery-72v-3800mah-ni-mh","title":"Drager PSS Merlin 7.2V Replacement Battery 33 51144","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eDrager PSS Merlin — 7.2V Ni-MH Replacement Battery (33 51144)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 7.2V 3800mAh Ni-MH battery replaces part number 33 51144 in the Drager PSS Merlin self-contained breathing apparatus. It powers the integrated electronics and alarm systems that firefighters and emergency responders depend on during hazardous atmosphere operations. Voltage and chemistry match OEM spec exactly — no adaptation required at the connector or BMS level.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003ePSS Merlin SCBA platform compatibility:\u003c\/strong\u003e\n    The PSS Merlin uses a fixed 7.2V Ni-MH rail to run its warning system, telemetry electronics, and low-pressure alarm. Any cell deviation in voltage or internal resistance causes the BMS to flag a fault before the unit clears self-test. This replacement matches the OEM chemistry so the handshake passes cleanly.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through the PSS Merlin's startup sequence and monitored BMS response at load. The unit completed self-test without fault flags, and the alarm circuit held steady across the full discharge curve.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap self-test protocol:\u003c\/strong\u003e\n    After installing this battery, let the PSS Merlin complete its full power-on self-test without interruption. The BMS runs a verification cycle at startup — cutting power mid-sequence triggers a false battery fault that locks in until the next complete reboot.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the PSS Merlin BMS behaves differently on a new Ni-MH cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eNi-MH cells ship in a partially discharged state and their internal resistance is higher before the first full cycle. The PSS Merlin's BMS compares internal resistance against a stored threshold — if the new cell reads high, the controller may flag a marginal battery even after a confirmed full charge. One complete charge-discharge cycle brings internal resistance within the expected window. After that cycle, the BMS registers the cell correctly and self-test clears normally.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eLow-battery alarm fires immediately after a full charge on the new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens because the PSS Merlin's charge IC applies a conservative voltage ceiling on an unfamiliar cell during the first charge — the cell does not reach its full resting voltage, so the BMS reads it as below threshold. The fix is to run one complete charge-discharge cycle on the device before operational deployment. After that cycle, resting voltage stabilises above 7.2V and the alarm threshold is no longer triggered at startup.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381401092186,"sku":"BWCS-DRM335MD-1","price":125.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381401124954,"sku":"BWCS-DRM335MD-2","price":149.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381401157722,"sku":"BWCS-DRM335MD-3","price":167.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-DRM335MD-1.webp?v=1778900536","url":"https:\/\/batteryweb.com\/products\/drager-pss-merlin-replacement-battery-72v-3800mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}