Vesta VESTA-027 Alarm Panel Replacement Battery 2.4V 700mAh

Vesta VESTA-027 HWC-1B-F1 / VESTA-224 WEZC-8 — 2.4V Ni-MH Replacement Battery (VESTA-250)

This 2.4V 700mAh Ni-MH cell replaces part number VESTA-250 in the Vesta VESTA-027 HWC-1B-F1 and VESTA-224 WEZC-8 wireless alarm control panels. It serves as the backup power source that keeps the panel active during a mains outage. When the original cell loses capacity, the panel can no longer hold its charge and will report a low battery fault.

• VESTA-027 and VESTA-224 compatibility: Both panels share the same 2.4V backup rail, VESTA-250 form factor, and float-charge circuit. The connector and cell footprint — 45 x 21 x 10.5mm — are identical across both models, so a single cell covers either platform.
• Bench tested on actual hardware: We ran this cell through charge acceptance and float stabilisation on a Vesta panel test rig. The BMS accepted the cell cleanly, moved into float charge within the expected window, and cleared the low battery fault flag after the conditioning period completed.
• Post-installation panel reset: Do not run a zone or siren test immediately after fitting this cell. The panel's float-charge circuit needs 24 to 48 hours to fully condition a new Ni-MH cell. Testing before that window closes will trigger a false low battery report on the panel display.

Alarm panel showing low battery hours after installing a new cell

Ni-MH backup cells in Vesta panels charge through a trickle float circuit, not a fast charger. A new cell arrives partially discharged, and the panel's BMS will not report a healthy battery state until the cell reaches its full float voltage — typically after 24 to 48 hours on continuous mains power. Triggering a test or cutting mains power before that point will confirm a low battery condition because the cell genuinely hasn't reached capacity yet. Leave the panel on mains for 48 hours before running any diagnostics or testing backup operation.

Alarm panel losing saved programming during a mains power outage after battery replacement

If the panel drops its programming when mains power fails, the replacement cell has not yet been accepted by the backup circuit — this is a conditioning failure, not a cell defect. The VESTA-250 backup circuit requires the cell to hold above 2.2V under load to sustain panel memory; a partially conditioned cell drops below that threshold quickly and the panel resets. Restore mains power, wait the full 48-hour conditioning window, then confirm the cell voltage holds above 2.2V before testing backup mode again.