About this replacement
Jetfon X500 — 3.7V Li-Polymer Replacement Battery (LB-X500)
This is a 3.7V, 1200mAh Li-Polymer battery for the Jetfon X500 cordless phone handset. It replaces part number LB-X500 when the original pack loses capacity or stops holding a charge. The battery slots into the handset and powers wireless communication with the base station.
- Jetfon X500 fitment: The X500 handset runs a 3.7V Li-Polymer cell with a specific connector and BMS negotiation tied to that voltage rail. This replacement matches the OEM cell dimensions (55.90 × 35.70 × 5.70mm) and voltage, so the handset electronics recognise the pack without fault codes.
- Bench tested on actual hardware: We ran the LB-X500 replacement through charge and discharge cycles on the bench. The BMS held cutoff cleanly at the correct thresholds — no overcharge bypass and no premature low-voltage trip during extended standby draw.
- First charge on a Li-Polymer handset: Unlike NiMH packs, this Li-Polymer cell does not need a long conditioning charge. Place the handset in the base until the charge indicator clears — typically a full charge cycle. Do not interrupt that first charge by lifting the handset mid-cycle, as the X500 base station calibrates its charge termination signal from that initial session.
Talk time shorter than the original battery after replacement
A new Li-Polymer cell sometimes reads lower capacity on the first two or three cycles because the electrolyte layers haven't fully activated. The X500 handset draws a consistent RF load during calls, which can expose this early-cycle shortfall. Run two or three full charge-to-depletion cycles through normal use and the pack will reach its rated 1200mAh. If capacity is still short after five cycles, check the base station contacts for corrosion — poor contact raises internal resistance and limits charge acceptance.
Handset not pairing with base station after battery swap
Removing the battery from a DECT handset cuts all power, and some DECT implementations store pairing data in volatile memory that resets during a full power loss. If the X500 handset shows no link or flashes a registration error after the swap, the fix is a manual re-pair rather than a battery fault. Hold the page or find button on the base station until the handset enters registration mode, then follow the X500 pairing sequence. Once paired, the handset retains the registration as long as the battery stays installed.