Telenot 35 973 Replacement Battery 7.2V 600mAh Ni-MH

Telenot 35 973 / FM 433 / F1011/S — 7.2V Ni-MH Replacement Battery (6/N-270AA)

This is a 7.2V 600mAh Ni-MH rechargeable battery for the Telenot wireless alarm system transmitter range, including the 35 973, FM 433, and F1011/S. It replaces OEM part 6/N-270AA. The cell sits inside the transmitter housing and maintains alarm signalling and wireless communication between system components during normal and backup operation.

• 35 973, FM 433, and F1011/S compatibility: All three transmitter models share the same 7.2V voltage rail, connector footprint, and BMS handshake protocol — which is why a single cell covers all three. The 84.00 × 28.60 × 14.50mm form factor fits the shared housing geometry without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, confirmed the BMS accepted the cell without fault codes, and verified the voltage held stable across communication bursts. No trip events were recorded during simulated zone signalling.
• Float charge conditioning before first alarm test: Do not run a zone or siren test immediately after swapping this cell. Allow 24–48 hours on float charge first. The panel samples battery voltage during its diagnostic cycle — a partially conditioned Ni-MH cell will read low and trigger a false low-battery fault even when the cell is healthy.

Why the Telenot panel still shows low battery after fitting a new cell

Ni-MH cells do not deliver their rated terminal voltage until they have completed at least one full charge cycle. When the panel's BMS samples voltage within the first few hours of installation, it reads the resting voltage of an uncharged cell — typically 6.8–7.0V — and flags a low-battery condition. This is not a fault with the cell. Keep the system powered and on charge for 48 hours. After conditioning, the terminal voltage stabilises at or above the panel's acceptance threshold and the fault clears automatically.

Alarm losing stored programming during a mains power outage after battery replacement

If the panel loses zone settings or installer codes during a power cut shortly after a battery swap, the backup cell had not yet been accepted by the panel's charge controller. A freshly installed Ni-MH cell needs 48 hours of mains-on charge to reach the capacity required for memory-hold backup. During that window, any mains interruption drops the supply below the panel's operating voltage before the cell can take over. Restore mains power, allow the full 48-hour conditioning period, then confirm the cell reads at least 7.0V under light load before testing backup operation.