Typhoon MyGuide 4500 Replacement Battery 3.7V 1400mAh

Typhoon MyGuide 4500 Series — 3.7V Li-Polymer Replacement Battery

This 3.7V, 1400mAh lithium-polymer cell replaces the original battery in the Typhoon MyGuide 4500, MyGuide 4500 SD, and MyGuide 4500 SD GPS portable navigation units. It fits the slim 66.25 × 50.85 × 3.96mm battery cavity and connects directly to the device's onboard power management circuit. Capacity figures are taken from the product specification — 1400mAh / 5.18Wh.

• MyGuide 4500 series fit: The 4500, 4500 SD, and 4500 SD GPS share the same battery bay dimensions, connector pinout, and power rail voltage. One cell covers all three variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the navigation board and confirmed the BMS handshake completed correctly — no false low-battery warnings and no premature cutoff at the GPS receiver load.
• Cold-start after power interruption: After fitting this cell, power the unit on outdoors before your first drive. The GPS performs a full cold start after any complete power loss — first satellite acquisition can take 5–10 minutes. Subsequent warm starts drop to under a minute once almanac data is cached.

GPS accuracy dropping as the battery level falls

Some GPS units, including portable automotive navigators, reduce receiver sensitivity when the battery voltage drops below a set threshold. The chipset draws less current to protect the remaining charge, and the receiver becomes less aggressive about tracking weak satellite signals. The result is wider position error or brief signal loss on routes with overhead obstructions. Keeping the cell above 3.5V under load maintains full receiver sensitivity.

MyGuide 4500 shutting off without a low-battery warning

After a battery swap, the device's fuel gauge IC has no learned capacity baseline — it is reading cell voltage rather than a calibrated charge curve. The displayed indicator can still show two bars when the cell is close to the BMS cutoff voltage of approximately 3.0V. Run two full charge-to-discharge cycles and the indicator recalibrates against actual cell behaviour. After that, the warning appears at the correct threshold instead of at the last moment.