Ultralife UBC005 Compatible Battery 3.7V 250mAh Li-Polymer

Ultralife UBC005 / UBP005 — 3.7V Li-Polymer Replacement Battery (HS-7)

This 3.7V 250mAh lithium-polymer cell replaces the factory battery in the Ultralife UBC005 and UBP005 wireless headsets. It also fits units identified by the part number UBC581730. At 32.00 × 17.20 × 5.75mm, it matches the original cell's footprint and connector exactly.

• UBC005 and UBP005 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — that's why one cell covers both. The base station reads the new pack through the same charge communication line used on the original.
• Bench tested on actual hardware: We cycled this cell through the UBC005 base station and monitored the BMS handshake during charge initiation. The protection circuit engaged correctly at end-of-charge, and the base station registered the pack without a charging error flag.
• First-cycle base station protocol: Place the headset in the base cradle immediately after fitting the new cell and leave it for one complete charge cycle before making a call. DECT headsets log the new cell's capacity during that first session — skip it and the talk-time estimate shown on the base will be inaccurate for several days.

Why the UBC005 cuts out mid-call even with a new battery

The UBC005 draws current from two loads simultaneously — the audio codec and the DECT radio transmitter. During active calls, that combined draw creates brief current spikes that can trip the cell's undervoltage protection if the pack hasn't been conditioned yet. A fresh cell at storage voltage (typically around 3.6V) has less headroom than a fully charged and conditioned pack. Run three to five full charge-discharge cycles and the issue usually clears as the cell reaches its rated capacity.

Base station shows full charge but headset cuts off after a few minutes

This happens when the replacement cell arrives at storage voltage and the base station terminates charge early — it reads a voltage that looks close to full but the cell hasn't actually completed a proper cycle. The BMS hasn't yet calibrated to the new cell's charge profile. Return the headset to the cradle for another full, uninterrupted session. If the base station light cycles to green and back to amber repeatedly, remove the headset, wait 10 seconds, re-seat it, and let the charge sequence restart from 0V detection — the base should then complete a full 4.2V charge to the cell.