Navman iCN320 Replacement Battery 3.7V 850mAh

Navman iCN320 / iCN330 — 3.7V Li-ion Replacement Battery

This 3.7V 850mAh lithium-ion cell replaces the original battery in the Navman iCN320 and iCN330 portable GPS navigators. These are compact vehicle navigation units — the kind mounted on a windscreen arm for turn-by-turn route guidance. Capacity is 850mAh (3.15Wh), matching the original specification.

• iCN320 and iCN330 compatibility: Both models share the same battery bay dimensions and 3.7V single-cell architecture. The connector and cell footprint are identical across the two units — 48.51 × 30.44 × 5.48mm — so one cell covers both.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a GPS navigation unit of this class. The protection circuit handled charge termination cleanly and held voltage above the BMS low-cutoff threshold through full discharge cycles without tripping prematurely.
• First fix after fitting: After any full power removal, the iCN320 loses its satellite almanac and performs a cold start. Take the unit outdoors with a clear sky view and leave it powered on for five to ten minutes before driving — this lets it rebuild the almanac so subsequent warm starts lock fast.

GPS accuracy reduced when battery charge drops low

Some GPS units dial back receiver sensitivity at low cell voltage to reduce current draw and extend operation. On the iCN320 this shows up as position drift or slower map tracking even when the unit stays powered on. The GPS receiver needs stable voltage — typically above 3.5V — to maintain full sensitivity. Fitting a fresh cell restores receiver performance immediately.

iCN320 shuts off without warning before the battery indicator hits empty

This happens when an aged cell's actual capacity has dropped well below what the fuel gauge expects. The gauge still shows bars remaining, but the cell voltage collapses under the load of the GPS receiver and backlit display, hitting the BMS cutoff threshold before the indicator reaches zero. A new 850mAh cell recalibrates the relationship between displayed charge and actual remaining voltage. After fitting, run one full charge-to-cutoff cycle so the indicator re-anchors to the new cell's voltage curve.