{"product_id":"oncourse-sirf-star-iii-replacement-battery-37v-1800mah-li-ion","title":"OnCourse SiRF Star III GPS Compatible Battery 3.7V 1800mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eOnCourse SiRF Star III — 3.7V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1800mAh Li-ion cell for OnCourse GPS navigators running the SiRF Star III chipset. It fits the specific form factor these portable navigation units require — 52.98 x 35.39 x 11.61mm. Fit this when the original cell no longer holds a charge or the unit shuts off unexpectedly during navigation.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSiRF Star III platform fit:\u003c\/strong\u003e\n    OnCourse units built around the SiRF Star III chipset share a common board layout and connector spec. This cell matches the voltage rail and physical footprint that platform requires — no adapter or modification needed.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on SiRF Star III hardware. The BMS responded correctly at both ends — no false cutoffs on charge, and discharge terminated cleanly at the low-voltage threshold without triggering a hard fault.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eCold start after power interruption:\u003c\/strong\u003e\n    After fitting this battery, power the unit on outdoors before driving. The GPS performs a cold start after any full power removal — first satellite acquisition takes 5 to 10 minutes. Subsequent warm starts drop back under a minute once the almanac data is rebuilt.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eGPS accuracy reduced at low battery on SiRF Star III units\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eWhen cell voltage drops toward 3.4V, some SiRF Star III units dial back RF receiver sensitivity as a power-saving measure. The chip is still tracking satellites, but weaker signals get dropped first. This shows up as position drift or a reduced satellite count on the status screen. Keeping the cell above 3.6V under load prevents the receiver from entering that reduced-sensitivity mode.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eUnit shuts off without warning during active navigation\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe battery indicator on these navigators reads voltage under no load — it does not account for the voltage sag caused by the GPS receiver and backlit display running together. A cell showing 30% can hit the low-voltage cutoff threshold under full draw before the indicator drops another bar. This is a calibration gap between the indicator and the actual cutoff point. If this is happening, treat the first battery warning as near-empty and plug into USB power rather than waiting for a second alert.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377723932762,"sku":"BWCS-BT388SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43377723965530,"sku":"BWCS-BT388SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43377723998298,"sku":"BWCS-BT388SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BT388SL-1.webp?v=1778771839","url":"https:\/\/batteryweb.com\/products\/oncourse-sirf-star-iii-replacement-battery-37v-1800mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}