About this replacement
Magellan Maestro 4000 Series — 3.7V Li-ion Replacement Battery (37-00030-001)
This 3.7V, 1100mAh Li-ion cell replaces the original battery in the Magellan Maestro 4000, 4000T, 4010, and 4040 portable GPS navigators. It matches the OEM part numbers 37-00030-001, E4MT181202B12, and MX0708. Capacity is 4.07Wh — identical to the factory specification.
- Maestro 4000 series compatibility: The 4000, 4000T, 4010, and 4040 share the same 3.7V battery bay, connector pinout, and charge circuit. One cell fits all four variants without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Maestro platform. The BMS accepted the cell without fault codes, and the charge circuit reached cutoff at 4.2V as expected.
- First satellite fix after fitting: After fitting this cell, power the unit on outdoors and let it run a full cold-start acquisition. The GPS has no stored almanac data after a full power removal — first fix can take 5–10 minutes. Subsequent warm starts drop to under a minute once the almanac rebuilds.
GPS accuracy reduced at low battery on the Maestro 4000
When cell voltage drops toward the lower end of the discharge curve, some Maestro units reduce RF receiver sensitivity to conserve power. This shows up as fewer satellites locked and a wider position error circle on screen. It is not a software fault — the GPS chipset pulls back deliberately. Keeping the battery above 3.6V under load maintains full receiver sensitivity.
Maestro 4000 shuts off without warning before the battery indicator empties
The on-screen battery gauge on the Maestro 4000 is calibrated to the original cell's discharge curve. A new cell — or a degraded one — may not match that curve exactly at low state-of-charge. The device hits its hardware voltage cutoff, typically around 3.3V, before the gauge visually reaches empty. If the unit is cutting out unexpectedly, run two full charge-to-cutoff cycles so the system re-learns the cell's actual discharge profile.