{"product_id":"rand-mcnally-tnd-550-replacement-battery-37v-1000mah-li-polymer","title":"Rand McNally TND-550 GPS Compatible Battery 3.7V 1000mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eRand McNally TND-550 \/ TND-540 — 3.7V Li-Polymer Replacement Battery (TOP 523450)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V 1000mAh lithium-polymer cell replaces the original TOP 523450 battery in the Rand McNally TND-550 and TND-540 trucking GPS navigators. It restores off-vehicle operation when the factory cell no longer holds a charge. Capacity is 1000mAh (3.7Wh) — matched to the original specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTND-550 and TND-540 compatibility:\u003c\/strong\u003e\n    Both models share the same battery bay geometry, connector pinout, and 3.7V supply rail. The TOP 523450 part number covers both, so one cell fits either unit 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 charge and discharge on the TND platform. The BMS accepted the cell without error flags, and the charge circuit terminated correctly at full voltage. No swelling or thermal anomaly was observed during the test run.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eCold-start satellite acquisition after swap:\u003c\/strong\u003e\n    After fitting this battery, power the unit on outdoors before driving. The TND-550 performs a GPS cold start following a full power interruption — first satellite fix can take 5–10 minutes. Subsequent warm starts drop that to under a minute once almanac data is cached.\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 the TND-550\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eAs the Li-Polymer cell drops toward its lower voltage threshold, some TND units reduce GPS receiver sensitivity to conserve power. This shows up as position drift or a delayed position update on the map, even on open roads with clear sky view. The fix is not a settings change — it is voltage. Keeping the cell above 3.6V under load maintains full receiver operation. Charge the unit or connect to vehicle power before the battery indicator reaches its last bar.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eTND-550 shutting off without a low-battery warning\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eAfter an aged battery is replaced, the fuel gauge IC on the TND-550 is still calibrated to the old cell's discharge curve. The device's low-battery threshold can trigger later than expected — or not at all — causing an abrupt shutdown mid-route. This is not a fault with the new cell. Run two or three full charge-to-discharge cycles to allow the gauge to recalibrate. After the third cycle, the warning LED and on-screen indicator should align with the actual remaining voltage, which reads approximately 3.5V at the cutoff point.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377567432794,"sku":"BWCS-RMD550SL-1","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43377567465562,"sku":"BWCS-RMD550SL-2","price":35.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43377567498330,"sku":"BWCS-RMD550SL-3","price":39.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-RMD550SL-1.webp?v=1778771668","url":"https:\/\/batteryweb.com\/products\/rand-mcnally-tnd-550-replacement-battery-37v-1000mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}