Apple iPod Nano 7th 616-0639 Compatible Battery 3.7V 200mAh

Apple iPod Nano 7th Generation — 3.7V Li-Polymer Replacement Battery (616-0639 / 616-0640)

This 3.7V, 200mAh Li-Polymer battery replaces the original cell in the Apple iPod Nano 7th Generation (A1446). It fits the slim chassis directly, matching the OEM dimensions of 39.65 × 33.26 × 1.63mm. If your Nano won't hold a charge or dies faster than it used to, this is the cell that needs replacing.

• iPod Nano 7 / A1446 fit: The 7th-generation Nano uses a flat Li-Polymer pouch cell with a specific connector orientation tied to the logic board layout. This replacement matches that connector and cell footprint — the BMS on the Nano's board communicates charge state through this connector, so a mismatched cell causes the device to report incorrect battery levels or refuse to charge.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a 7th-gen Nano logic board. The BMS accepted the cell without error flags, and the charge circuit pulled correct trickle current at the start of each cycle.
• First charge after installation: Media players frequently enter deep discharge protection after a cell swap. Connect the Nano to a charger immediately after installing this battery and leave it for at least 30 minutes before attempting to power on — this lets the charge circuit exit trickle mode and bring the cell up to a normal operating voltage.

Battery percentage jumping around after a cell swap on the Nano 7

The iPod Nano 7 estimates charge state by reading cell voltage against a stored lookup table calibrated to the original battery's discharge curve. After a cell swap, that table no longer matches the new cell's actual curve. The indicator recalibrates over several full charge and discharge cycles. Expect erratic percentage readings for the first two to three cycles — this is the controller relearning voltage thresholds, not a fault with the replacement cell.

Playback cutting out before the battery indicator shows empty

The audio amplifier in the Nano 7 draws a brief current spike during playback, especially at higher volumes. As the cell approaches the end of its discharge curve, voltage sags under that load even when the indicator still shows charge remaining. The BMS interprets the voltage drop as a cutoff condition and shuts the device down to protect the cell. If this happens repeatedly, run two full charge cycles so the controller recalibrates its low-voltage threshold — it should stabilise around 3.0V before cutoff.