Battery and power faults can reduce or remove the system’s standby capability
Keep the dedicated mains supply available where safe, avoid repeated discharge tests and escalate promptly if batteries are hot, swollen, leaking or the panel cannot remain operational on standby.
MOST LIKELY CAUSES
Start with the power and battery information
Symptom variations Match the exact battery, charger and PSU behaviour. ⌄
- Battery fault returns
- Panel fails standby test
- Battery casing swollen
- Different voltages across matched batteries
- Installation date exceeds maintenance policy
Safe first checks Checks for authorised site staff before engineering work. ⌄
- Record the exact battery, charger or PSU message.
- Check whether the mains indicator is normal.
- Look for swelling, heat, leakage or loose external leads.
- Check whether a recent mains failure occurred.
- Do not intentionally discharge the system while a battery or charger fault is active.
Step 1 — Check the installation and test history Follow the site fire procedure and avoid unnecessary battery discharge while power faults are active. ⌄
Review battery age, previous test results and recent mains failures.
Step 2 — Inspect for physical deterioration Follow the site fire procedure and avoid unnecessary battery discharge while power faults are active. ⌄
Do not handle leaking, hot or badly swollen batteries unnecessarily.
Step 3 — Replace as a matched set Follow the site fire procedure and avoid unnecessary battery discharge while power faults are active. ⌄
Use the correct type and capacity specified for the panel and calculated standby duty.
What the indication usually means How this battery or power condition develops. ⌄
Fire alarm batteries need replacing when testing shows inadequate capacity, excessive internal resistance, imbalance, leakage, swelling or repeated battery faults.
Engineer diagnostic sequence Competent-person checks after the site information has been captured. ⌄
- Confirm required standby and alarm capacity.
- Test conductance, impedance or discharge performance as approved.
- Check charger operation before fitting new batteries.
- Replace both batteries in a series pair together.
- Record date, capacity and test results in the system log.
Information and equipment needed Useful items for accurate fault finding. ⌄
- Panel and PSU make and model
- Required standby and alarm duty
- Battery capacity, age and installation date
- Manufacturer-approved meter and battery test equipment
- System log book and recent mains-failure history
Parts that may be involved Components commonly associated with this fault. ⌄
- Correct-capacity matched battery set
- Battery labels
- Replacement leads or terminals
- Battery fuse
- Disposal arrangements
When immediate action is required Conditions that should trigger escalation or an impairment plan. ⌄
- The panel cannot remain operational on standby.
- Batteries are hot, swollen, leaking or producing an unusual smell.
- The charger or PSU fault affects alarm outputs, signalling or interfaces.
- The battery fuse repeatedly operates.
- The system has experienced a prolonged mains failure.
- The required standby duration cannot be demonstrated.
Frequently asked questions Common battery and power questions. ⌄
Is battery voltage alone enough to prove condition?
No. A battery can show an acceptable open-circuit voltage but still have poor capacity or high internal resistance.
Should only one battery in a series pair be replaced?
Normally no. Batteries in the same series set should be replaced together with matched type, capacity and age.
Can corroded terminals simply be cleaned?
Only after checking for leakage, heat and battery deterioration. Damaged leads or leaking batteries should be replaced.