Logitech Z515 Replacement Battery 3.6V 2000mAh Ni-MH

Logitech Z515 / S315i / S715i — 3.6V Ni-MH Replacement Battery (180AAHC3TMX)

This is a 3.6V, 2000mAh Ni-MH rechargeable battery for the Logitech Z515, S315i, and S715i wireless speakers. It replaces OEM part numbers 180AAHC3TMX and 993-000459. When the original cell loses capacity and the speaker dies faster than it used to, this is the direct swap.

• Z515, S315i, and S715i compatibility: All three models run the same 3.6V single-cell Ni-MH pack with the same connector and physical footprint. The BMS on each expects the same charge termination behaviour, so one battery covers the full group.
• Bench tested on actual hardware: We cycled this battery through the Z515 charging circuit and confirmed delta-V cutoff triggered correctly at full charge. The cell held stable output voltage under sustained amplifier draw without triggering premature shutdown.
• Ni-MH cycling care for desk speakers: Ni-MH cells develop memory effect when repeatedly charged from a high state. Run the Z515 down to near-empty at least once a month before plugging it in — this keeps the fuel gauge accurate and slows capacity fade specific to shallow-cycle use patterns.

Audio distorting before the battery indicator reaches empty on the Z515

Ni-MH cells don't hold voltage flat all the way to zero — they sag progressively as the cell depletes. The Z515 amplifier needs enough voltage headroom to drive clean audio, and once the cell drops below roughly 3.0V under load, the amplifier clips before the low-battery indicator triggers. The result is distorted output even though the indicator hasn't shown empty yet. Replacing an aged cell with a fresh 2000mAh pack restores the voltage buffer the amplifier relies on.

Z515 getting warm during extended play sessions

Heat in the Z515 housing comes from two sources running at the same time: the amplifier stage dissipating power as audio output, and the Ni-MH cell generating heat during discharge. The fabric enclosure traps both. An old cell with high internal resistance generates significantly more heat at the same current draw than a fresh cell does. If the speaker is noticeably warm after an hour of play, internal resistance in the battery is the most likely cause — a new cell will run cooler at the same volume level.