Apple iPOD 1st Gen Replacement Battery 3.7V 2200mAh

Apple iPod 1st & 2nd Generation — 3.7V Li-Polymer Replacement Battery (P325385A4H)

This is a 3.7V, 2200mAh Li-Polymer battery for the Apple iPod 1st and 2nd Generation portable media players. It replaces part number P325385A4H, the original flat-cell pack that sits behind the hard drive in both units. Capacity is rated at 8.14Wh, matching the original spec.

• 1st and 2nd Generation fit: Both models share the same logic board voltage rail, the same flat Li-Polymer form factor, and the same two-pin connector pinout. One replacement cell covers both generations without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a 1st Generation unit. The BMS accepted a full charge without fault, held voltage above 3.5V through the discharge curve, and tripped the low-voltage cutoff cleanly at the expected threshold.
• Post-swap initialisation tip: If the iPod sits in storage for months before installation, the new cell may arrive in a low-voltage protection state. Connect to a known-good FireWire or USB charger and leave it for 30 minutes before attempting to power on — the protection circuit needs a slow trickle before it accepts a normal charge current.

Battery percentage jumping after cell swap on iPod 1st Generation

The original iPod uses a simple voltage-threshold fuel gauge, not a coulomb counter. After a cell swap, the firmware has no stored discharge curve for the new cell, so it maps voltage readings to percentage estimates that were calibrated for an aged original cell. This mismatch causes the indicator to jump — sometimes from 80% to 20% in one track. Run two or three full charge-to-cutoff cycles and the gauge settles as the firmware re-learns the new cell's voltage curve. Expect accurate readings after the third full cycle.

Playback cutting out before the battery indicator shows empty

The iPod's audio amplifier draws a brief current spike when the codec loads a new track or when the hard drive spins up to buffer audio. At the tail end of discharge, cell voltage sags under that spike and dips below the BMS cutoff threshold — even though the indicator still shows charge remaining. The fix is a full recalibration cycle: charge to 100%, play continuously until the unit shuts off on its own, then charge fully again. After one calibration cycle the cutoff and the displayed percentage align more closely, and the premature shutdowns stop.