Gigaset SL800H Pro Replacement Battery 3.7V 830mAh

Gigaset SL800H Pro / SL750H Pro Series — 3.7V Li-ion Replacement Battery

This 3.7V 830mAh Li-ion battery replaces the internal pack in the Gigaset SL800H Pro cordless handset and several related models in the SL series. It fits the SL800H Pro, SL750H Pro, SL610 Pro, SL400H, and four additional variants. When the original cell no longer holds charge, this pack restores the handset to normal operation.

• SL-series handset compatibility: These Gigaset models share the same slim 3.7V Li-ion cell format, connector pinout, and BMS handshake protocol. The SL800H Pro and SL750H Pro both draw from the same base-station charge circuit, so one battery spec covers the full group.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SL800H Pro platform. The BMS accepted the charge handshake without fault codes, and the protection circuit tripped correctly at low-voltage cutoff — no false shutdowns at full draw.
• First-charge protocol for Li-ion cordless handsets: After fitting the new cell, seat the handset in the base cradle and leave it undisturbed for a full charge cycle before first use. The SL800H Pro's charge circuit uses a slow trickle phase that Li-ion cells need to reach rated capacity from a storage state of charge.

Talk time shorter than the original battery after replacement

A new Li-ion cell ships at partial charge — typically 40–60% — and the first full cycle rarely delivers rated capacity straight away. The SL800H Pro's power management reads state of charge from voltage curves, which are skewed until the cell has been fully cycled two or three times. Run the handset from a full charge down to auto-shutdown, then return it to the base for a full recharge. Capacity stabilises after three to five of these cycles.

Handset loses pairing with the base station after battery swap

Removing power from a DECT handset clears the volatile memory that holds the base station pairing record on some Gigaset models. The SL800H Pro stores pairing data in non-volatile flash, but a prolonged power gap during the swap can still trigger a re-registration prompt. Go to the handset menu, select Register Handset, and enter the base PIN — the factory default is 0000 on most Gigaset bases. Once re-registered, the handset resumes normal operation on the same base line.