{"product_id":"fisher-f-690-replacement-battery-6v-2100mah-ni-mh","title":"Fisher F-690 6V Ni-MH Replacement Battery 2100mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFisher F-690 \/ F-820 \/ FM-80 Series — 6V Ni-MH Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 6V, 2100mAh Ni-MH replacement battery for Fisher cameras including the F-690, F-820, FM-80, and FVC-10, plus 36 additional compatible models. It slots into the same battery compartment as the original and feeds the same 6V rail. Capacity is rated at 12.6Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eF-690 \/ F-820 \/ FM-80 platform compatibility:\u003c\/strong\u003e\n    These models share a common 6V battery architecture, the same physical form factor, and a consistent connector orientation across the line. A single cell covers the full group without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through the camera's onboard BMS at 6V and confirmed the protection circuit responds correctly to charge termination — the BMS trips cleanly at full capacity without overcharge creep.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst charge cycle on camera body:\u003c\/strong\u003e\n    On first install, run one full charge through the camera body or OEM charger before shooting. Some Fisher BMS implementations require an internal charge cycle to correctly map the new cell's discharge curve to the battery-remaining indicator.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eCamera showing dead battery indicator on a partially charged replacement cell\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eNi-MH cells have a flatter discharge curve than the Li-ion cells many modern camera indicators are calibrated against. The camera's voltage-threshold logic can misread a Ni-MH cell that still has significant charge remaining and flag it as depleted. This is a display mapping issue, not a cell fault. Run one full charge-discharge cycle and the indicator will track more accurately against the actual state of charge.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBattery percentage jumping erratically on the display mid-shoot\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the camera's percentage readout is interpolating from voltage snapshots rather than coulomb counting. Ni-MH cells show a shallower voltage drop per unit of discharge than the OEM cell the firmware was tuned for, so the indicator recalculates and jumps. Flash firing and continuous autofocus cause brief current spikes that temporarily pull voltage down, triggering another recalculation. Charge the battery fully, then run a complete discharge cycle in-camera to let the BMS recalibrate its reference points.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43333893095514,"sku":"BWCS-NP55-1","price":35.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43333893128282,"sku":"BWCS-NP55-2","price":41.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43333893161050,"sku":"BWCS-NP55-3","price":45.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NP55-1.webp?v=1778213590","url":"https:\/\/batteryweb.com\/products\/fisher-f-690-replacement-battery-6v-2100mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}