Mercury 13.8V 25A Switch Mode PSU - 345W

The Mercury is a 13.8V 25A switch mode power supply unit delivering regulated 345W output through three screw terminal channels. The 13.8V output voltage matches the charging voltage of a fully charged 12V lead-acid battery, making the PSU compatible with systems designed to run on battery backup or mains-battery hybrid installations without voltage drop issues.

Designed for radio communication equipment, security and alarm systems, access control installations and 12V DC LED lighting, the PSU suits applications where stable voltage under varying load is needed. The three output channels distribute the 25A maximum current across separate connections, preventing overload on individual terminals. Built-in short-circuit and overload protection with auto-reset shuts the PSU down under fault conditions and restores output once the fault clears.

The fan-cooled metal enclosure measures 220x50x115mm and weighs 0.85kg, making it compact enough to fit in control cabinets, rack enclosures or behind wall-mounted equipment. The IP20 rating means it is intended for indoor use in dry, climate-controlled environments where direct water or dust ingress is not a concern. The adjustable voltage trim pot allows fine-tuning of the output voltage within the 12.42V-15.18V range to suit specific load requirements.

The PSU runs on 240V AC mains at 4A input and operates across a working temperature range of -10°C to 40°C. The screw terminal block on the front panel accepts solid or stranded conductors up to 2.5mm² for mains input and DC output connections, with clearly labelled ADJ, V+, COM, earth, neutral and live terminals.

Product Manual

Why is the output 13.8V instead of 12V?

13.8V is the float charge voltage of a fully charged 12V lead-acid battery. Systems designed to run on mains-battery backup expect this voltage to keep batteries topped up while powering connected equipment without causing voltage sag issues. The adjustable voltage range (12.42V-15.18V) allows trimming to match specific battery chemistry or load requirements.

What does the auto-reset protection do?

If a short-circuit or overload occurs, the PSU shuts down to protect itself and the connected load. Once the fault is cleared (for example, a short is removed or excess load is disconnected), the PSU automatically restores output without needing to be manually reset or power-cycled.

Can it be used outdoors or in damp environments?

No. The IP20 rating means the PSU is protected against solid objects larger than 12.5mm but has no protection against water or dust ingress. It must be installed indoors in a dry, climate-controlled environment such as a control cabinet, rack enclosure or equipment room.

What wire size do the screw terminals accept?

The screw terminal block accepts solid or stranded conductors up to 2.5mm² cross-section. Ensure conductors are securely tightened and that polarity is observed when wiring DC output connections.