Burglar Alarm Battery Replacement: Costs, Lifespans and What's Involved
By the DC Fire & Security engineering team — installing and maintaining fire and security systems since 2010. Updated June 2026.
Quick answer
A burglar alarm has several batteries on different clocks: the panel's rechargeable backup battery lasts 3–5 years (engineer replacement, typically £75–£150 on a service visit), wireless detector lithium batteries last 2–5 years (often DIY-replaceable), and the bellbox battery lasts around 5 years. Most 'alarm faults' are simply one of these reaching end of life.
Every battery in your system, and how long it lasts
| Battery | Typical life | Symptoms when failing | Who replaces it |
|---|---|---|---|
| Panel backup (rechargeable SLA) | 3–5 years | Beeping after power cuts, 'battery fault' on keypad, 3am chirps | Engineer — inside tampered panel |
| Wireless PIR / contact (lithium) | 2–5 years | Low battery warning naming the zone, intermittent false alarms | Often DIY; engineer at service |
| Bellbox battery | ~5 years | Bellbox self-sounding, strobe flickering, tamper faults | Engineer — working at height, tamper |
| Keyfob batteries | 1–3 years | Reduced range, multiple presses needed | DIY (coin cells) |
Can I replace alarm batteries myself?
Wireless detector and keyfob batteries: usually yes — put the system into its engineer/walk-test or battery-change mode first per the manual, or the tamper switch will trigger the siren when you open the case. Panel and bellbox batteries: have an engineer do them. The panel battery sits behind a tamper switch on mains-adjacent equipment and needs the right capacity; the bellbox involves ladder work on a tampered, self-powered sounder that will fight back if handled wrong.
Why battery health matters more on monitored systems
The panel battery is what keeps protection alive through a power cut — a tired battery turns a routine outage into an unprotected building and a flood of ARC signals. Police-response systems log every battery-related false signal against the URN. Annual servicing exists substantially to catch batteries before they fail: the engineer load-tests the panel battery and reads the charge data rather than waiting for the 3am chirp.
Frequently Asked Questions
How much does an alarm battery cost?
Why is my alarm beeping after a power cut?
Will the alarm still work while a battery is low?
Do battery changes happen at the annual service?
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