Grundig D770A Cordless Phone Compatible Battery 2.4V 550mAh

Grundig D770A — 2.4V Ni-MH Replacement Battery (SN1352)

This is a 2.4V 550mAh Ni-MH replacement battery for the Grundig D770A cordless telephone handset. It slots into the handset battery compartment and restores talk and standby function when the original pack has faded. OEM part number SN1352 confirms fit for this model.

• D770A handset fit: The D770A uses a 2.4V two-cell Ni-MH pack at a fixed connector pitch. This replacement matches that voltage rail and physical footprint, so the handset BMS accepts the pack without a fault condition on the base station.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a DECT handset platform at 2.4V. The BMS accepted charge from the base cradle on the first placement with no error light triggered.
• First charge on NiMH cordless handsets: After fitting this battery, seat the handset in the base and leave it for a full 16 hours before the first call. NiMH cells shipped from storage sit at a partial charge state — skipping the slow first charge leaves capacity unrealised across the first several cycles.

Talk time shorter than the original battery after replacement

NiMH cells need three to five full charge-discharge cycles before they reach rated capacity. A new pack coming out of storage has not been through those cycles, so the first few days of use will feel short. This is not a fault with the cell — it is how NiMH chemistry works. Run the handset until the low-battery indicator shows, return it to the base for a full charge, and repeat for at least three cycles before judging talk time.

Base station shows no charge or error light with new battery installed

NiMH packs stored for extended periods can drop below the voltage threshold the base station uses to detect a valid battery. The D770A base expects to see a minimum voltage before it begins charging — if the pack reads too low, the base interprets it as an absent or faulty cell. Remove the handset, leave it off the base for 30 seconds, then reseat it firmly. If the error persists, confirm the pack voltage with a multimeter — a resting voltage above 1.8V total across the pack should allow the base to begin its charge cycle.