About this replacement
Apple iPod Shuffle — 3.7V Li-Polymer Replacement Battery (616-0212)
This is a 3.7V, 250mAh Li-Polymer replacement battery for the Apple iPod Shuffle, including models MB523LL/A, MB686LL/A, and MB519LL/A. It replaces OEM part number 616-0212 — the slim, foil-pouch cell that fits inside the Shuffle's compact aluminium shell. Capacity matches the original specification from the product data.
- iPod Shuffle MB5xx series compatibility: These Shuffle variants share the same 3.7V voltage rail, identical connector pitch, and the same physical cell footprint at 31.60 × 19.14 × 4.28mm — which is why one part number covers all listed models.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Shuffle unit. The BMS accepted charge current without flagging a fault, held voltage within the expected Li-Polymer discharge curve, and cut off cleanly at the low-voltage threshold.
- Post-swap trickle charge: After installing this battery, connect the Shuffle to its USB charger before powering it on. Li-Polymer cells sitting at low state-of-charge can enter a protection state that blocks normal charge current — a slow trickle for 20–30 minutes pulls the cell voltage up past the BMS re-enable threshold before full charging begins.
Why the iPod Shuffle goes dark after sitting unused for months
Li-Polymer cells self-discharge at roughly 2–3% per month at room temperature. After six months or more in a drawer, a Shuffle's cell can drop below 2.5V — the point where the BMS locks out discharge to prevent permanent cell damage. When you press the power button, nothing happens because the protection circuit is actively blocking output. This is not a dead unit. Connecting the charger and waiting 30 minutes gives the trickle stage time to raise cell voltage above 3.0V, at which point the BMS releases the lockout and normal charging resumes.
Playback cutting out before the battery indicator shows empty
At the tail end of a Li-Polymer discharge curve — typically below 3.4V — the audio amplifier inside the Shuffle can no longer draw enough current without causing the cell voltage to sag below its operating floor. The device interprets this as a fault and shuts down, even though the fuel gauge still shows some charge remaining. A new cell with a lower internal resistance holds voltage more firmly under the amplifier's load, which closes the gap between what the gauge reads and what the amp actually needs. If cutouts return quickly after fitting a new cell, check that the USB charge cycle ran to completion — a partial charge leaves the cell on the steepest part of the sag curve.