Royal Digital BS4100 BT GPS HXE-W01 Replacement Battery 3.7V 1000mAh

Royal Digital BS4100 BT GPS — 3.7V Li-ion Replacement Battery (HXE-W01)

This 3.7V, 1000mAh Li-ion cell replaces the OEM HXE-W01 battery in the Royal Digital BS4100 BT GPS navigator. It fits the original battery bay and connects to the same BMS interface the unit expects. Voltage and capacity match the stock specification exactly.

• BS4100 BT GPS platform fit: The BS4100 BT GPS combines a live GPS receiver with a Bluetooth radio, both drawing from this single cell. The HXE-W01 footprint — 52.96 × 33.64 × 5.15mm — is specific to this unit. No modification to the bay or connector is required.
• Bench tested on actual hardware: We cycled this cell through charge and discharge under combined GPS-receiver and Bluetooth radio load. The BMS held the cutoff threshold correctly and did not trip prematurely during the radio-active phase of the test.
• Cold-start satellite acquisition after swap: After fitting this cell, power the unit on outdoors before first use. The GPS performs a cold start following any full power interruption — first satellite fix typically takes 5–10 minutes outdoors with clear sky view. Subsequent warm starts resolve in under a minute once the almanac is cached.

GPS accuracy reduced at low battery on the BS4100

Some GPS receivers scale back radio-frequency sensitivity when cell voltage drops toward the low-battery threshold — the BS4100 exhibits this behaviour. The unit prioritises self-preservation over receiver gain, which narrows the number of satellites it can lock. Position error increases noticeably below roughly 3.5V. Keeping the cell above that threshold by charging before extended use prevents the sensitivity reduction.

Device shuts off without visual low-battery warning

After a full battery swap, the BS4100's fuel gauge is uncalibrated — it has no charge history to reference. The on-screen indicator may show two or three bars right up to the point the cell hits the BMS cutoff voltage. This is not a fault with the replacement cell; it is the gauge working from stale internal data. Run one complete charge-to-cutoff cycle and the indicator will re-calibrate to the new cell's actual capacity curve. Target a full charge to 4.2V before that first cycle.