About this replacement
Honeywell 5800RP Wireless Repeater — 6V Ni-MH Replacement Battery (55111-05)
This is a 6V 700mAh Ni-MH battery for the Honeywell 5800RP Wireless Repeater. The 5800RP boosts signal range between wireless sensors and the main security panel. When this battery fails, the repeater loses its backup power and wireless zones it supports can drop off the network.
- 5800RP Wireless Repeater compatibility: The 5800RP uses a dedicated 6V Ni-MH cell with a specific connector and footprint matched to the repeater's internal housing. OEM part numbers 55111-05 and K0257 both reference this same cell. The GP80AAAH5B3BMX is the underlying cell configuration — same voltage rail and charge circuit expectations across all three references.
- Bench tested on actual hardware: We ran this cell through the 5800RP's charge circuit and confirmed the BMS accepted it without fault codes. Float charge behaviour was stable, and the cell reached rated capacity without triggering an overcharge cutoff.
- Post-installation charge conditioning: Do not run a zone test immediately after swapping this cell. The 5800RP's panel communication requires 24–48 hours on float charge before the battery reports full. Running diagnostics before that window closes will cause the panel to flag a low battery condition on the repeater even with a new cell installed.
Why the 5800RP keeps reporting low battery after a fresh cell swap
The 5800RP does not read battery state directly from cell voltage at the moment of installation. It samples the battery over a supervised charge window — typically 24 to 48 hours — before updating its status to the main panel. A new Ni-MH cell installed at a partial state of charge will cause the panel to continue showing a low battery fault during this window. This is normal charge acceptance behaviour for Ni-MH chemistry under trickle charge. Leave the repeater powered and connected for at least 48 hours before clearing the fault at the panel.
Wireless zones dropping off the network after a repeater battery replacement
If sensors that rely on the 5800RP for range extension stop checking in after the battery swap, the repeater may have lost its RF sync during the power interruption. The 5800RP stores its learned device table in non-volatile memory, but a prolonged power gap — more than a few seconds without mains or battery — can cause it to revert to an unregistered state. Check the repeater's LED status: a slow blink typically indicates it is not yet communicating with the panel. Re-enroll the 5800RP through the panel's RF device menu and confirm the repeater's RF ID is re-accepted before testing zone check-ins.