About this replacement
SpectraLink S33 DECT Handset — 3.7V Li-ion Replacement Battery (84743430)
This 3.7V, 1200mAh lithium-ion battery replaces the original pack in the SpectraLink S33 and S33 DECT handset. It fits the cordless DECT handset directly, restoring power to the unit when the original cell has degraded after repeated charge cycles. OEM part numbers 84743430 and BT229865 both apply to this handset.
- S33 and S33 DECT handset fit: Both model variants share the same battery bay dimensions and connector pinout — 53.20 × 34.00 × 5.50mm — so one cell covers the full S33 range without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a DECT handset platform. The BMS held the 3.7V nominal rail steady and tripped protection only at the low-voltage floor — no premature cutoff under RF transmit load.
- First installation charging tip: Seat the handset in the base for a full charge before first use. Li-ion cells shipped in partial-charge storage state may register low on the handset's fuel gauge until one full charge cycle completes.
Talk time shorter than rated after installing the new battery
A freshly installed Li-ion cell coming out of storage is rarely at full calibration with the handset's fuel gauge circuit. The handset reads state-of-charge based on voltage curves, and a cell that hasn't completed a full cycle yet will report capacity low. Run one full charge from the base, then use the handset until it powers off from low battery. Recharge fully — after that cycle, the gauge reading stabilises against the actual cell capacity.
Base station shows no charge or error light after battery swap
Some SpectraLink base units check incoming voltage before enabling the charge circuit. A cell shipped at storage voltage — typically 3.5V or below — can fall under the base's acceptance threshold, causing the charge LED to stay dark or show a fault. Place the handset in the base and leave it undisturbed for 15–20 minutes. The base trickle-charges the cell up to the threshold, then switches to normal charge mode. If the light still won't change, confirm the handset contacts are clean and fully seated.