About this replacement
Magellan RoadMate 2145T-LM — 3.7V Li-ion Replacement Battery (MR2045)
This is a 3.7V 720mAh Li-ion cell replacing the original MR2045 battery in the Magellan RoadMate 2145T-LM and related portable GPS navigators. It fits the RoadMate 2136T-LM, 2120T, 2120T-LM, and four additional models in the same series. Voltage and capacity match the original spec exactly.
- RoadMate 2100 series compatibility: These models share the same 3.7V power rail, physical footprint (50.98 × 36.44 × 5.60mm), and connector orientation. The MR2045 part number covers all variants listed — no hardware modification needed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a RoadMate unit. The protection circuit responded correctly to charge termination and low-voltage cutoff without tripping prematurely during GPS receiver operation.
- Cold-start satellite acquisition after swap: After fitting this cell, power the GPS on outdoors and let it run until it acquires a satellite fix before use. A full power interruption clears the GPS receiver's ephemeris cache, so the first fix after a battery swap can take 5–10 minutes. Subsequent warm starts return to under a minute.
GPS accuracy reduced as battery level drops on active navigation
The RoadMate reduces GPS receiver sensitivity at low battery to protect remaining charge. This shows up as position drift or brief signal loss before the low-battery icon appears. The receiver pulls more current during active route recalculation than during straight-line tracking, which accelerates the drop. A fully charged replacement cell keeps receiver sensitivity at full spec throughout the session.
RoadMate 2145T-LM shuts off without warning before the battery icon goes red
The on-screen battery indicator on these units is calibrated against the original cell's discharge curve. An aged or degraded cell reaches the voltage cutoff threshold before the indicator visually registers critical. The unit cuts power immediately — no warning screen. After fitting a fresh 720mAh cell, the indicator recalibrates over the first two full charge and discharge cycles, after which the warning appears at the correct voltage level near 3.2V.