{"product_id":"viavi-jdsu-est-120-replacement-battery-6v-4500mah-ni-mh","title":"Viavi 5KR-CH JDSU EST-120 Replacement Battery 6V 4500mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eViavi JDSU EST-120 \/ EST-125 \/ EDT-135 — 6V Ni-MH Replacement Battery (5KR-CH)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 6V 4500mAh Ni-MH replacement battery for the Viavi JDSU EST-120, EST-125, and EDT-135 OTDRs. It slots directly into the battery compartment and matches the original 5KR-CH specification. All three instruments share the same voltage rail and pack form factor, so one part number covers the full group.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eEST-120, EST-125, and EDT-135 compatibility:\u003c\/strong\u003e\n    These three OTDR models run from the same 6V bus and use the same physical pack housing with identical connector orientation. The BMS handshake is passive on this chemistry — no authentication chip to negotiate, so the instrument reads voltage directly from the cells.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through full charge and discharge on a programmable load and confirmed the 5-cell Ni-MH stack holds stable output through the mid-discharge plateau. The BMS protection circuit tripped correctly at the low-voltage cutoff without latching — the instrument recovered cleanly on reconnect.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install calibration on the EST-120:\u003c\/strong\u003e\n    After fitting the new pack, run a full calibration cycle through the OTDR's instrument menu before heading into the field. The EST-120 maps battery state during calibration. Skip this step and the low-battery warning can trigger early on 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\"\u003eEST-120 BMS lockout after the pack sat unused in a carry case for months\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eNi-MH cells self-discharge continuously. A pack stored for three to six months can drop below the BMS recovery threshold — typically under 4.5V for a 5-cell stack. When the instrument sees this voltage, it refuses to power on, and placing the pack on the charger may show no charge activity at all. The fix is a trickle pre-charge: use a standalone Ni-MH charger set to a low current (around 100mA) for 30–60 minutes to bring the pack above 5V, then transfer to the standard charger to complete the cycle.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eOTDR readings reset or freeze mid-logging session with no warning\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eDuring a sustained OTDR logging session, the laser source and DSP draw current simultaneously. On a partially discharged Ni-MH pack, this combined load can pull cell voltage below the instrument's operating floor for a fraction of a second — long enough to trigger a reset. This is not a firmware fault. It is a voltage sag caused by the pack's rising internal resistance as cells age. If resets are happening consistently at the same point in a test sequence, check resting voltage before the next session — a healthy 6V Ni-MH pack should read at least 6.8V immediately after a full charge.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43360607109210,"sku":"BWCS-JDT120SL-1","price":70.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43360607141978,"sku":"BWCS-JDT120SL-2","price":82.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43360607174746,"sku":"BWCS-JDT120SL-3","price":91.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-JDT120SL-1.webp?v=1778615988","url":"https:\/\/batteryweb.com\/products\/viavi-jdsu-est-120-replacement-battery-6v-4500mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}