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MIKE'S TOOLKIT
MIKE'S TOOLKIT HOMEPAGE

Q&A Calculator

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Required Battery Capacity:0.00 Ah

Designed for BS5839-1 Standard Requirements: For most systems, batteries must cover 24 hours standby plus a 30-minute alarm. This can be reduced to 6 hours if an auto-start generator is present or increased by the time the site is likely to be unoccupied, for 72 hours max.
How it's calculated: This uses your standby and alarm loads including a 30-minute alarm, applying fixed factors for battery inefficiency (de-rating: 1.75) and long-term aging (aging factor: 1.25) for simplicity.

Mains Power Supply Check

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Required Battery Capacity:0.00 Ah

How it's calculated: Uses the selected standby time plus a fixed 15-minute alarm period, applying fixed factors for battery inefficiency (de-rating: 1.75) and long-term aging (aging factor: 1.25) for simplicity.

Mains Power Supply Check

Video Guides

How to carry out Q&A load tests

  1. Connect your meter on the batteries in series (between the + from the panel and the + of the battery) and set it to DC Amps.
  2. Turn the mains off.
  3. Measure the result (Quiescent).
  4. FIRE - Test a MCP with all outputs enabled.
    INTRUDER - Test bell outputs at the keypad 32>1>ON
  5. Measure the result (alarm load).
  6. Silence the panel
  7. Restore mains, remove meter, restore batteries and then reset panel.
  8. Input readings into this calculator!

Important Safety Notice: These tests should only be performed by a competent and qualified engineer. Powering down certain addressable panels (e.g., Gent, Siemens) can lead to system faults or failures. Proceed with caution and professional knowledge. Please read the full disclaimer here.

How to carry out a power supply test

  1. Disconnect the batteries.
  2. Locate a 24v constant output.
  3. Measure the Voltage.
  4. FIRE - Test a MCP with all outputs enabled.
    INTRUDER - Test bell outputs at the keypad 32>1>ON
  5. Measure the Voltage
  6. Remove the meters
  7. Silence the panel
  8. Restore batteries and reset panel.
  9. Input readings into this calculator!

Formula Involved

Fire Alarm Battery Calculation:

$$ C_{min} = 1.25 \times ((I_1 \times T_1) + 1.75 \times (I_2 \times 0.5)) $$

Intruder Alarm Battery Calculation:

$$ C_{min} = 1.25 \times ((I_1 \times T_1) + 1.75 \times (I_2 \times 0.25)) $$

Mains Power Supply Voltage Drop:

$$ \text{Voltage Drop \%} = \frac{|V_{standby} - V_{alarm}|}{V_{standby}} \times 100 $$

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