When installing replacement batteries in a fire alarm control unit that uses a 24VDC system with two 12VDC batteries in series, the batteries must be:

Question: When installing replacement batteries in a fire alarm control unit that uses a 24VDC system with two 12VDC batteries in series, the batteries must be:

Answer options:

• Double the AH rating of the first battery
• A mix of 6V and 12V cells to reach 24V
• Installed in separate rooms to prevent heat buildup ✅ Of the same date of manufacture and AH rating

Correct answer: Of the same date of manufacture and AH rating

Explanation: When two or more batteries are connected in series (to get 24V from two 12V), they must be of the same age, manufacturer, and amp-hour (Ah) rating to ensure even charging and discharging. If one is old, it will kill the new one or create a charging 'blind spot'. S524 and battery best practices (referenced in S536/S537). S524 4.1.6 refers to battery maintenance requirements. 4.1.6.1 mentions they must be identical.