Altronix SMP3PMCTX 12/24VDC Supervised Power Supply
The Altronix SMP3PMCTX is a wall- or panel-mounted supervised power supply and battery charger built for security and access control installations where power continuity and fault monitoring are non-negotiable. This single-output enclosure accepts 115/230VAC input and delivers selectable 12VDC or 24VDC with integrated battery backup and dual-path supervision—AC fail detection and low-battery alert—so you know immediately when primary power is lost or the backup is running low.
Key Features
- Selectable 12VDC or 24VDC output: field-selectable voltage means one SKU handles both legacy 12V installs and newer 24V access control hardware without inventory complexity.
- AC fail and low-battery supervision: built-in monitoring contacts alert you to power loss or backup depletion—no external relay module needed—reducing wiring and panel real estate.
- Integrated battery backup: accepts internal or external sealed lead-acid or lithium batteries, allowing you to size runtime based on load and facility requirements; critical for access control systems that must unlock on power loss or maintain credential readers during outage.
- Single supervised output channel: one 24VDC regulated output with current limiting protects downstream loads from overcurrent conditions; the SMP3PMCTX does not provide multiple independent channels, so it's a point-source supply, not a distribution hub.
- 115/230VAC input voltage: accepts both North American (115VAC) and international (230VAC) mains without reconfiguration, useful for multi-region deployments or retrofit scenarios.
- Enclosure form factor: DIN-rail or surface-mounted metal housing rated for indoor electrical closets and equipment racks; not suitable for outdoor or harsh HVAC environments without external protective cabling.
- Lifetime Limited Warranty: manufacturer stands behind the unit for the life of the installation—standard for Altronix infrastructure products—covering defects in materials and workmanship.
Output Current Ratings
Output capacity varies by voltage selection. At 12VDC, the SMP3PMCTX supplies up to 6A—enough for six 1A readers or equivalent distributed load. At 24VDC, it delivers up to 10A, a meaningful boost for higher-power solenoid locks or multiple-reader arrays. This rating is the continuous maximum; actual runtime under battery backup depends on battery amp-hour capacity and load draw. If your access control load exceeds these ratings, you'll need a larger supply or a multichannel power distribution module with additional outputs.
Integration & Compatibility
The SMP3PMCTX pairs naturally with access control panels and readers from industry vendors supporting 12 or 24VDC inputs—door locks, magnetic strikes, request-to-exit sensors, and badge readers are all compatible. Battery terminals accept standard automotive or industrial sealed lead-acid packs; confirm amp-hour and terminal type with your battery supplier. The supervision outputs are hardwired contacts, so integration with a security panel's fault input or a building management system's alarm relay requires physical wiring—there is no network interface or modbus on this model. For networked facilities running a centralized NVR or access control server, plan to route supervision signals back to your control hub via a dedicated 2-wire or 4-wire run.
Real-World Deployment Notes
The SMP3PMCTX is a workhorse for small-to-medium access control zones—a single door or a small suite of readers on one power rail. If you're powering a 10-door facility, you'll likely install two or three units distributed across the building to avoid long 24VDC runs that incur voltage drop. Load your battery backup math carefully: a typical magnetic lock draws 0.3–0.5A; if you need that lock to hold for 15 minutes on battery, you're looking at a 100 AH+ battery, which is physically large and requires a separate enclosure. For mission-critical doors, pair the SMP3PMCTX with a UPS-class lithium battery module to achieve minutes of holdover on a compact form factor.
Frequently Asked Questions
Q: Can I parallel two SMP3PMCTX units to increase output current?
A: No. Paralleling regulated supplies without diodes or load-sharing circuitry causes one unit to backfeed into the other, damaging components. If you need higher current, deploy additional supervised supplies on separate sections of your system, or upgrade to a multichannel Altronix power distribution module in the same family.
Q: What battery types work with the SMP3PMCTX?
A: The unit accepts sealed lead-acid (12V, 24V) or lithium batteries with matching voltage. Always confirm amp-hour capacity and terminal type with Altronix or your battery supplier before installation. Mismatched voltage will damage the charger circuit.
Q: Is the SMP3PMCTX suitable for outdoor HVAC cabinets or gate operators?
A: No. The enclosure is rated for indoor use only. Outdoor or high-humidity installs require a weatherproof rated cabinet or a separate environmental enclosure—plan for cable glands and conformal coating on exposed connectors.
Q: What does the AC fail signal do if my panel doesn't monitor it?
A: The AC fail contact is a hardwired dry relay output. If your access control panel or security system does not wire that contact to an input, the signal is unused. You lose early warning of mains loss. Always tie supervision outputs to your control hub's fault input for complete system awareness.
Q: Can the SMP3PMCTX power a Wi-Fi access reader or IP intercom?
A: Yes, if the device draws ≤6A @ 12VDC or ≤10A @ 24VDC and tolerates regulated DC supply. However, the SMP3PMCTX has no network interface—it is purely a power and backup unit. Network devices must be wired separately to your LAN for control and management.
Ted PerryPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
The Altronix SMP3PMCTX is the foundation-layer power supply you reach for when a single access control zone—or a small cluster of readers—needs both continuity and real-time fault awareness. The selectable 12/24VDC output is genuinely handy for retrofit jobs where legacy 12V hardware coexists with new 24V locks; field-switching saves a second SKU. What sets it apart in a crowded market is the dual supervision architecture: AC fail detection and low-battery alerting are both hardwired contacts, not software flags on a networked device. That means you get early warning of power loss even if your network is partitioned.
Technical Highlights:
- Dual supervision outputs (AC fail + low battery): hardwired relay contacts—no network dependency—ensure your control panel knows immediately when mains is gone or backup is nearly depleted. This is critical for facilities where a silent power loss could lock occupants in a room or disable emergency exit hardware.
- Current capacity 6A @ 12VDC, 10A @ 24VDC: sufficient for four to six typical door readers plus one solenoid lock, or three to four higher-power magnetic strikes. Exceeding these limits requires a second supply or a larger distribution module; there is no soft overload rollback, only current limiting to protect the output.
- Integrated battery charger and backup: the SMP3PMCTX charges and monitors a connected battery internally; no external charger relay needed. Runtime depends entirely on battery amp-hour rating and actual load draw—a 5 AH lead-acid battery will hold a 2A load for roughly 2.5 hours, minus efficiency losses.
Deployment Considerations:
- Battery sizing is often underestimated: a 10-minute holdover for a magnetic lock (0.5A draw) requires at least a 1–1.5 AH battery; most facilities retrofit 7–12 AH batteries inside a separate cabinet to be safe. Plan space and cable routing now or you'll have a rat's nest of lead-acid packs later.
- Supervision wiring must go somewhere. If your access control panel has no dedicated fault input, or if supervision signals need to reach a remote security monitoring center, you're running dedicated 2-pair cabling—not a trivial install in retrofit. Budget labor accordingly.
- The 115/230VAC input is switchable, not automatic. Confirm your local mains voltage and set the supply accordingly during commissioning or you'll destroy the internal transformer.
The SMP3PMCTX is best suited for small, physically distributed access control sites—a multi-tenant office building with one supply per floor or stairwell, or a retail environment with a single secure door and staff room reader. It is not a hub; it is a purpose-built point-source supply with battery backup and supervision built in. For larger facilities with 10+ powered zones, you'll migrate to a supervised power distribution board or a networked power management system. For this niche—one or two high-reliability DC rails with battery holdover—it's a proven choice.
