We have created this handy tool to determine the correct battery size for the fire alarm system you are designing, the calculations used are correct and up to date to comply with British Standard - BS5839 Part 1.
The standard states that in the event of a mains supply failure, the backup battery should be able to run the system for a minimum of 24hrs, followed by 30 minutes in full alarm condition (all sounders/output devices running). This applies to categories L & M.
If the system is category P then the above applies if the building is continuously manned. If however the building is not continuously manned, then the standby time may need to be 72hrs. (The standby period will be determined from the risk assessment) To use the Eurotech Battery Calculator simply fill in your quiescent (standby) load and alarm load (both in milliamps) followed by your standby period in hours. Click on SUBMIT to accurately calculate the minimum battery size required for the panel.
Once the calculation is on-screen you’re able to click ‘Download PDF’ to download a full copy of the calculation for your future reference.
Please note - If a larger battery is found to be required (typically for a 72 hour standby) a higher capacity charger may be necessary to achieve the required recharge of the battery.
Please consult the Eurotech technical team if in doubt.