So, today I was doing some work for my workplace, when a critical 4G modem-router dropped offline, cutting me off. Figuring it was a temporary issue, I thought I’d resume this headset rebuild.
The replacement battery had turned up a few weeks back, a beefy 1000mAh 3.7V LiPo pack intended for Raspberry Pi PiJuice battery supplies. This pack was chosen because it has a similar arrangement to the original Logitech battery: single cell with a 10k thermistor. As a bonus, the pack appears to be at least triple the original cell’s capacity. I just had to wire it up.
The connectors are not compatible, being both physically different sizes and the thermistor and 0V pins being swapped. Black and Red are the same conventions on both packs, that is, red for +3.7V and black for 0V… the thermister connects to the blue wire on the old pack and yellow on the new pack.
I’m at two minds whether to embed the electronics directly into the earmuffs, or whether to just wire the microphone/speaker connections to a DIN-5 connector to make it compatible with my other headsets.
For now at least, the battery is charging, not getting hot, and the circuitry detects the base transceiver when it is plugged into a laptop USB port, so the circuitry is still “functional”.