About this replacement
Packard Bell Compasseo 820 / 500 — 3.7V Li-ion Replacement Battery (CM-2)
This is a 3.7V 1100mAh Li-ion replacement for the CM-2 battery cell used in the Packard Bell Compasseo 820 and Compasseo 500 portable GPS navigators. It slots directly into the battery bay and connects to the same BMS contacts as the original. Capacity is 1100mAh (4.07Wh), matching the original cell specification.
- Compasseo 820 and 500 compatibility: Both units share the same battery bay dimensions, connector pinout, and 3.7V supply rail. The CM-2 part number covers both devices — one cell fits either unit without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Compasseo platform. The BMS accepted a full charge without fault flags, and the protection circuit tripped correctly at low-voltage cutoff — no runaway, no false cutoffs mid-use.
- Cold start after power interruption: After fitting this cell, power the GPS fully on outdoors before driving. The unit performs a cold satellite acquisition after any complete power removal — first fix takes 5–10 minutes outdoors. Subsequent warm starts drop to under a minute once almanac data is cached.
GPS accuracy reduced at low battery on the Compasseo 820
The Compasseo 820 receiver draws consistent power from the cell to maintain signal sensitivity. At low state of charge — typically below 3.5V — the unit throttles receiver power to extend operation. This reduces signal acquisition strength and can cause position jumps or missed turns on active routes. Keep the cell above this threshold by connecting to a car charger on longer journeys.
Device shuts off without low-battery warning
After a battery swap, the Compasseo's fuel gauge is uncalibrated to the new cell. The software-side voltage threshold that triggers the on-screen warning may not fire before the hardware cutoff voltage is reached. The unit cuts power without the usual alert. Run two or three full charge-to-discharge cycles to let the gauge recalibrate — the warning indicator realigns to the actual cutoff point, which sits at approximately 3.0V.