Uniden 5822 Cordless Phone Replacement Battery 3.6V 700mAh

Uniden 5822 / 5823 / 5829 / 5845 Series — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 700mAh Ni-MH rechargeable battery for Uniden cordless phone handsets including the 5822, 5823, 5829, and 5845, plus 42 additional compatible models. It replaces the original factory cell when the handset can no longer hold a charge through a normal conversation. Same voltage, same chemistry, same physical footprint as the OEM pack.

• 5822 / 5823 / 5829 / 5845 platform fit: These Uniden handsets share the same 3.6V single-cell NiMH architecture, connector orientation, and physical cell bay dimensions — 45.90 x 31.20 x 10.70mm — so one replacement pack covers the full model range without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a Uniden handset base, confirming the base accepted the NiMH voltage curve without triggering a charge fault and that the BMS delivered stable current to the handset circuit throughout the discharge phase.
• First-charge protocol for NiMH handsets: After installing, seat the handset in the base and leave it for a full 16 hours before using it. NiMH cordless phone cells arrive partially discharged from storage and need a slow, uninterrupted first charge to reach rated capacity.

Talk time shorter than the original battery after replacement

NiMH cells don't deliver full rated capacity on the first cycle. The electrochemical structure needs three to five full charge-discharge cycles before the active material is fully utilised. If talk time feels short after the first charge, run the handset until the low-battery indicator activates, then return it to the base for a full charge. Repeat this three to five times and capacity will stabilise at the rated 700mAh.

Base station charge light stays red or shows an error after fitting the new pack

NiMH batteries that have sat in storage can drop below the voltage threshold the base uses to confirm a valid pack is present. Some Uniden bases will flash an error or refuse to switch from fault mode to charge mode when the incoming voltage reads too low. Place the handset in the base, leave it undisturbed for 30 minutes, then remove and reseat it firmly — this allows the trickle-charge circuit to nudge voltage up to the acceptance window. If the error clears, the base will resume normal charging automatically.