Sony BP-DM10 Discman D-220 Replacement Battery 2.4V 1800mAh

Sony Discman D-220 Series — 2.4V Ni-MH Replacement Battery (BP-DM10)

This is a 2.4V, 1800mAh Ni-MH replacement for the Sony BP-DM10 battery pack. It fits the Discman D-220, D-223, D-321, and D-4215P portable CD players. Capacity figures come from the product data — 4.32Wh total energy.

• D-220 series compatibility: These Discman models share the same 2.4V two-cell Ni-MH architecture, physical form factor, and connector pinout. The BP-DM10 slot accepts this cell without modification across all listed variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a D-220 unit. The internal protection circuit held charge termination correctly at full capacity, and the player's low-battery cutoff triggered at the expected voltage floor without premature shutdown.
• Ni-MH cycle conditioning on first use: Ni-MH cells can arrive partially discharged from storage. Run one complete charge-discharge cycle before relying on the battery indicator — the Discman's charge circuit calibrates remaining-charge display against the cell's actual capacity after the first full cycle.

Why the Discman D-220 stops mid-track on a new battery

The D-220's optical pickup and spindle motor draw current in short bursts as the laser seeks and the disc accelerates. A fresh Ni-MH cell that hasn't been conditioned can show elevated internal resistance, causing a brief voltage sag during those bursts. The player's undervoltage protection reads that sag as a dead cell and cuts power. One full charge cycle reduces internal resistance and eliminates most mid-playback dropouts.

Battery indicator showing full — then player shuts off seconds later

Ni-MH cells have a relatively flat discharge curve, which means the Discman's simple voltage-threshold indicator stays in the "full" zone for most of the discharge, then drops fast at the end. A cell nearing the end of its capacity will appear fully charged right up until the voltage collapses below the 2.0V cutoff. If the player shuts off immediately after showing a full indicator, confirm cell voltage with a multimeter — a resting reading below 2.2V on a charged cell means the cell is no longer holding capacity and needs replacement.