Garmin iQue 3600 Replacement Battery 3.7V 1600mAh Li-ion

BTI GPS-GAR3200 — 3.7V Li-ion Replacement Battery (PW029123)

This is a 3.7V 1600mAh Li-ion replacement battery for the Garmin iQue 3600 handheld GPS navigator. It replaces part number PW029123 and fits directly into the iQue 3600's battery bay. Capacity is rated at 1600mAh (5.92Wh), matching the original cell specification.

• iQue 3600 fitment: The iQue 3600 uses a compact single-cell Li-ion pack at 3.7V nominal. This cell matches that voltage rail and the connector orientation required by the device's power management circuit — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the iQue 3600 platform. The BMS held cutoff voltage correctly and the device registered a full charge without throwing a charge-fault indicator.
• First-use satellite acquisition: After fitting this battery, power the iQue 3600 on outdoors with a clear sky view and let it run a full cold-start satellite acquisition before relying on navigation. A cold start after any full power interruption takes significantly longer than a warm start — plan for the first fix to take up to 10 minutes.

GPS accuracy reduced as the iQue 3600 battery drops below 3.5V

The iQue 3600's GPS receiver draws more current during active satellite tracking than during standby. As cell voltage drops toward the lower end of the discharge curve, some GPS units reduce receiver sensitivity to stay within power budget. On the iQue 3600, this can show as degraded position accuracy or slower re-acquisition after going indoors. Keeping the cell above 3.5V under load keeps the receiver running at full sensitivity.

iQue 3600 shuts off without warning before the battery indicator hits empty

The iQue 3600's battery gauge is calibrated against the original cell's discharge curve. A new replacement cell may have a slightly different curve, so the on-screen indicator and the actual cutoff voltage don't align until the device has completed a few full charge-discharge cycles. The device hits the hardware low-voltage cutoff before the software indicator reaches zero, which looks like a sudden shutdown. Run two or three full cycles — charge to 4.2V, discharge through normal navigation use — and the gauge will recalibrate.