Lenco Nav400 Replacement Battery 3.7V 1400mAh

Lenco Nav400 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1400mAh (5.18Wh) lithium-ion cell for the Lenco Nav400 portable GPS navigator. It replaces the original battery when capacity has degraded and the unit no longer holds a charge through a full journey. Physical dimensions are 50.22 × 36.88 × 6.52mm — confirm against your existing cell before fitting.

• Nav400 battery fit: The Nav400 runs a single-cell 3.7V Li-ion pack at this form factor. No multi-cell balancing or proprietary BMS handshake is involved — the protection circuit sits on the cell itself and handles over-charge, over-discharge, and short-circuit cutoff directly.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, confirmed the protection circuit trips correctly at the low-voltage threshold, and verified it returns to normal charge acceptance after a recovery charge from a depleted state.
• First satellite fix after fitting: After fitting this cell, power the Nav400 on outdoors and let it run a full cold-start satellite acquisition before driving. A cold start after full power removal can take 5–10 minutes for the first fix — subsequent warm starts will be under a minute once the almanac data is cached.

GPS accuracy reduced at low battery on the Nav400

Some GPS units, including compact navigators in this class, step down receiver sensitivity when the cell voltage drops below a certain threshold. This reduces current draw but degrades position accuracy — you may see the position dot drifting or snapping to incorrect road segments. The Nav400 display may still show two or three battery bars when this happens, because the indicator is not calibrated to the actual cell voltage curve. A fresh cell restores full receiver power and stabilises the fix.

Nav400 shutting off without warning during navigation

An aged cell loses capacity but also develops higher internal resistance, which causes voltage to sag sharply under the load of the GPS receiver and backlit display running together. The unit hits its low-voltage cutoff while the battery indicator still shows partial charge, so there is no visual warning before shutdown. This is a cell-condition issue, not a firmware fault. Fitting a new cell with lower internal resistance eliminates the sag and restores the expected shutdown sequence at the correct threshold.