Philips S9A Cordless Phone Compatible Battery 3.7V 500mAh

Philips S9A / S9H Series — 3.7V Li-ion Replacement Battery (PH422943)

This is a 3.7V, 500mAh Li-ion replacement battery for the Philips S9A, S9A/34, S9A/38, and S9H cordless DECT handsets. It slots into the handset battery compartment and restores power to the handset. Voltage and form factor match the OEM spec: 44.20 × 29.94 × 4.35mm.

• S9A and S9H handset compatibility: These models share the same battery bay geometry, voltage rail, and connector pinout. One battery covers all four variants without modification.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on the S9A platform. The protection circuit held charge termination at the correct voltage and responded cleanly to the base station charge current.
• First charge on a Li-ion handset battery: Unlike NiMH packs, this Li-ion cell does not need a 16-hour conditioning cycle. Place the handset in the base until the charge indicator clears — typically one full charge cycle from a depleted state is enough to reach rated capacity.

Talk time shorter than the original battery after replacement

A new Li-ion cell often ships at partial state of charge after storage. The first one or two cycles may feel shorter than expected — this is normal. The cell reaches rated capacity around cycle three once the electrodes have fully activated. Run two or three complete charge-discharge cycles through normal use before assessing talk time against the 500mAh rating.

Handset not pairing with the base after battery swap

Removing a DECT handset battery cuts power completely, and some Philips S9-series handsets drop their pairing registration when power is lost. The handset will show no signal or fail to ring after reinstall. Re-register the handset using the base station menu — on most S9 models, hold the paging button on the base for five seconds, then follow the on-screen prompt on the handset to complete re-pairing.