Grandstream WP822 Compatible Battery 3.7V 1800mAh Li-Polymer

Grandstream WP822 / WP825 — 3.7V Li-Polymer Replacement Battery (GS-02)

This is a 3.7V, 1800mAh Li-Polymer replacement battery for the Grandstream WP822 and WP825 cordless handsets. It replaces OEM part number GS-02 and fits the battery bay on both models without modification. Capacity is 1800mAh (6.66Wh), matching the original specification.

• WP822 and WP825 compatibility: Both handsets share the same battery footprint, connector pinout, and BMS communication protocol — a single cell covers both. The Li-Polymer chemistry matches the voltage curve the handset firmware expects during charge and discharge cycles.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the WP825 handset. The BMS accepted charge from the base station without fault, cell temperature stayed within normal range, and the protection circuit tripped correctly at low-voltage cutoff.
• First-cycle charging on the WP822/WP825: After installing this battery, seat the handset in the base station and leave it there for a full charge before making calls. Li-Polymer cells shipped from storage may read a low state of charge, and the handset's charge indicator can show full before the cell actually reaches capacity on the first fill.

Talk time shorter than expected after fitting the GS-02 replacement

Li-Polymer cells arrive from storage partially discharged, and the first one or two charge cycles rarely deliver full rated capacity. The handset's fuel gauge also recalibrates over the first few full cycles — early readings can look low even when the cell is healthy. Run two to three full charge and discharge cycles before drawing conclusions about capacity. By cycle three, the cell should be delivering close to its 1800mAh rating.

Handset loses DECT pairing after battery replacement

Removing the battery from a WP822 or WP825 cuts all power to the handset, which can clear the DECT pairing stored in volatile memory on some firmware versions. This is not a battery fault — it is a power-loss event. To restore pairing, put the handset into registration mode and re-register it to the base station through the handset menu under Settings → Pairing. The process takes under two minutes and the battery does not need to be at full charge for it to complete.