Ericsson DT412 Replacement Battery 3.7V 700mAh Li-ion

Ericsson DT412 — 3.7V Li-ion Replacement Battery

This is a 3.7V 700mAh Li-ion battery for the Ericsson DT412 cordless DECT handset (also listed as part 6027581). It replaces the original cell when the handset can no longer hold a charge between base sessions. Dimensions are 59.10 × 41.60 × 14.50mm — measure your existing pack before ordering if you are unsure.

• DT412 and 6027581 compatibility: Both references point to the same Ericsson DECT handset platform. The battery connector, cell footprint, and 3.7V nominal voltage match the original pack exactly — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the DT412 platform. The protection circuit responded correctly at low-voltage cutoff and did not trigger false over-current trips during normal standby and talk draw.
• First charge after install: Place the handset in the base immediately after fitting the new battery and leave it for a full 16 hours before use. Li-ion cells shipped in storage state need a complete first charge to register accurate capacity with the handset's charge circuit.

Talk time shorter than original battery after replacement

A new Li-ion cell does not always deliver full rated capacity on the first cycle. The handset's charge circuit needs two to three full charge-and-discharge cycles to calibrate to the new cell's actual capacity curve. During this break-in period, the handset may show a lower battery indicator than expected. Run three complete cycles — full charge, use until the handset signals low battery, then charge fully again — and capacity will stabilise at the rated 700mAh.

Handset not pairing with base after battery swap

Removing the battery from a DECT handset cuts power to volatile memory, which can erase the stored base pairing on some Ericsson models. The handset will power on normally but fail to register calls or show a no-link indicator. Re-register the handset through the base station's subscription menu — on most Ericsson DECT bases, hold the paging button for five seconds to enter registration mode, then follow the handset prompt.