Altronix SMP3PMCTX220 12/24VDC Supervised Power Supply with Battery Backup
Overview
The Altronix SMP3PMCTX220 is a supervised, battery-backed power supply designed for commercial security installations where regulated DC output and fault notification are non-negotiable. Housed in a large cabinet measuring 13.5" x 13" x 3.25", it delivers 2.5A of continuous current at either 12VDC or 24VDC — selectable to match the field devices you're powering — and keeps them running through an AC outage using two onboard 12VDC/7AH batteries. For installers building out access control panels, intrusion systems, or mixed-device security enclosures, the SMP3PMCTX220 consolidates power, supervision, and battery management into a single listed assembly.
Altronix is one of the most widely specified names in Altronix power supplies for commercial security — the SMP3PMCTX220 fits squarely in their supervised, cabinet-class line. If you're specifying security power supplies for monitored installations, this unit's Form C contacts for both AC failure and low battery give your control panel or monitoring equipment the relay outputs it needs to annunciate faults without adding an external supervision module.
Key Features
- Selectable 12VDC or 24VDC Output: A single unit covers both 12V and 24V field devices — useful when your installation mixes legacy 12V readers with 24V locking hardware. Set it once at commissioning; no additional regulation hardware required.
- 2.5A Continuous Output: 2.5 amps of steady-state current handles moderate multi-device loads — think two to four electric strikes plus ancillary low-draw devices — without thermal derating. Size your load budget to stay at or below this figure across all connected devices simultaneously.
- Dual 7AH Battery Backup: Two 12VDC/7AH batteries provide meaningful standby capacity. At a 1A average load, you're looking at several hours of operation through an AC outage — relevant for installations that need to meet UL or local AHJ runtime requirements. Batteries mount internally to keep the footprint compact.
- AC Failure Supervision — Form C Contacts: The Form C relay output for AC failure lets your panel or alarm receiver log a tamper/trouble condition the moment utility power drops, without polling. This is the supervision architecture most UL-listed monitoring stations expect — hardwired relay, not a software ping.
- Low Battery Supervision — Form C Contacts: A separate Form C output for low battery means you get distinct annunciation when the standby capacity degrades, rather than a combined fault that masks the failure mode. Useful for service dispatch — the technician arrives knowing whether it's an AC issue or a battery replacement.
- Wide Input Voltage Range: Accepts 115VAC at 50/60Hz or 230VAC (198VAC–256VAC), so the same unit ships to sites on either North American or international mains without a transformer swap. If you're supporting facilities with mixed utility feeds or international campus deployments, this dual-range input removes a procurement variable.
- Operating Temperature 0°C to 49°C: Rated for standard indoor mechanical room and IDF closet environments. Not rated for unheated exterior enclosures or rooftop equipment rooms where ambient temps can drop below freezing — plan accordingly when specifying site locations.
- CE Agency Listing: CE marking confirms the unit meets applicable European electromagnetic compatibility and safety directives — relevant for international projects or when your specs sheet requires a listed assembly.
Integration & Compatibility
The SMP3PMCTX220 is a general-purpose supervised power supply, not a proprietary panel accessory. Its output voltage and Form C supervision contacts are compatible with a broad range of access control panels, intrusion panels, and alarm communicators that accept dry-contact supervision inputs. The 12/24VDC selectable output pairs directly with common electric strikes, magnetic locks, and motion detectors that specify either rail. When integrating with a panel that monitors supervision contacts, wire the AC failure and low battery Form C outputs to dedicated zone or auxiliary inputs — consult your panel's wiring guide for normally-open vs. normally-closed configuration, as Form C contacts support either state.
For larger installations requiring higher current or more output channels, consider stepping up within the Altronix power supply line to a higher-amperage or multi-output model. The SMP3PMCTX220's 2.5A ceiling is appropriate for focused single-enclosure loads; distributed multi-door access control head-ends typically require per-door supplies or a higher-capacity chassis. Pair this unit with a UPS or secondary backup solution if your site requires extended runtime beyond what dual 7AH batteries provide.
Frequently Asked Questions
Q: Can the SMP3PMCTX220 output both 12VDC and 24VDC simultaneously?
A: No. The output voltage is selectable — either 12VDC or 24VDC — set at installation. It operates at one voltage level at a time, not both simultaneously.
Q: What battery size does the SMP3PMCTX220 accept?
A: The unit is designed to house two 12VDC/7AH sealed lead-acid batteries internally. Both batteries are required for full rated standby capacity.
Q: Does the SMP3PMCTX220 work with 230VAC mains power?
A: Yes. The unit accepts 115VAC (50/60Hz) or 230VAC (198VAC–256VAC), making it suitable for both North American and international mains without an external transformer.
Q: What do the Form C supervision contacts connect to?
A: The Form C relay contacts for AC failure and low battery connect to a panel, alarm receiver, or monitoring system that accepts dry-contact supervision inputs. They allow your monitoring equipment to receive distinct fault annunciation for each condition — AC loss and battery degradation are reported separately.
Q: Is the SMP3PMCTX220 rated for outdoor or unheated enclosure installation?
A: No. The operating temperature range is 0°C to 49°C, which covers standard indoor environments. It is not rated for locations where ambient temperature drops below freezing.
Q: What is the continuous current output of the SMP3PMCTX220?
A: The unit delivers 2.5A of continuous output current at the selected voltage (12VDC or 24VDC). Size your connected load budget to remain at or below this figure across all devices simultaneously.
The SMP3PMCTX220 is a unit I reach for when a single-enclosure access control or intrusion installation needs supervised, battery-backed power with clean relay outputs — and the load sits comfortably under 2.5A. The selectable 12/24VDC output is genuinely useful in retrofit scenarios where you're inheriting a mix of legacy 12V readers and newer 24V locking hardware in the same enclosure; one power supply, one compliance conversation with the AHJ.
Technical Highlights:
- Dual Form C Supervision: Separate relay contacts for AC failure and low battery mean your panel gets two distinct trouble inputs, not a single aggregated fault. That specificity matters when you're dispatching service — a technician who knows it's a low-battery condition rather than an AC failure arrives with the right parts.
- Dual 7AH Battery Capacity: Two 12VDC/7AH batteries in parallel give you meaningful standby time. At moderate loads — say 1–1.5A average — you're looking at four to six hours of runtime, which covers most utility outage scenarios in commercial buildings and satisfies many AHJ standby requirements.
- Wide Input Range (115/230VAC): The 198–256VAC high-line acceptance isn't just for international sites — it also provides tolerance against voltage sag on aging commercial electrical infrastructure, where nominal 120VAC can dip below 110V during peak demand.
Deployment Considerations:
- Confirm your total connected load stays under 2.5A with all devices energized simultaneously, including inrush from electric locks on access events. It's easy to undercount if you spec the supply against steady-state current only.
- Operating temperature bottoms out at 0°C — if this enclosure lives in an unheated utility closet in a cold climate, verify the room maintains temperature above freezing during winter. Sealed lead-acid batteries lose capacity sharply below 0°C even if the supply itself operates correctly.
This unit is well-suited for single-door or two-door access control head-ends in commercial office, retail, or light industrial settings where the AHJ requires supervised power with discrete fault annunciation and the electrical room stays within the 0°C–49°C operating band.
