Altronix AL400UL 12/24VDC Dual-Voltage Power Supply and Battery Charger
The Altronix AL400UL is a field-selectable 12/24VDC power supply and battery charger rated at 4A @ 12VDC or 3A @ 24VDC. This dual-voltage design eliminates the need to stock separate SKUs when deploying mixed-voltage access control, alarm, and emergency signaling systems across a facility. Integrated battery backup and supervised relay outputs provide both power continuity and system status reporting during AC mains failure.
Key Features
- Selectable 12VDC or 24VDC output voltage: Field-configurable at installation time — no need to order different models for different equipment, reducing procurement complexity and spare parts inventory.
- 4A @ 12VDC or 3A @ 24VDC maximum current: Handles multiple door controllers, card readers, or alarm modules on a single supply — verify your load before deployment, as current is inversely proportional to voltage selection.
- Integrated sealed lead acid or gel-type battery charger: Charges backup batteries on-board without requiring external charging equipment. Batteries are sold separately — specify SLA or gel type only; lithium backup is not supported by this design.
- AC Failure Form C supervision contacts: Relay output signals when AC mains are lost, allowing networked devices or monitoring centers to log power events and trigger failover logic.
- Battery Form C supervision contacts for low-voltage alarm signaling: Separate relay output alerts when battery voltage drops below threshold, giving you advance warning before backup power is exhausted.
- Single output channel with supervised operation: One power rail per unit — if you need multiple independent supplies, install multiple AL400UL units or consider a higher-channel Altronix power distribution module.
- Operating temperature range 0°C to 49°C (32°F to 120°F): Standard indoor rating — avoid placing this unit in uncontrolled outdoor cabinets or extreme environments without climate control or enclosure upgrade.
- Compact 12.25" × 7.25" × 4.5" footprint: Fits standard 19-inch rack rails or DIN mounting within a wall-mounted access control cabinet — verify shelf clearance before specifying.
- UL294, UL603, UL1069, UL1481, MEA NYC, CSFM approvals: Meets life safety and security equipment certification standards recognized in municipal and institutional deployments — confirm local authority jurisdiction requirements before installation.
- Lifetime Limited Warranty: Covers defects in materials and workmanship; review Altronix warranty terms for exclusions and return procedures.
Integration and Compatibility
The AL400UL accepts 115VAC, 60Hz input at 3.5A — verify that your facility's backup power source (UPS, generator, or dedicated circuit) can supply this draw. The dual relay outputs (AC Failure and Battery Low) integrate with any access control system, burglar alarm panel, or emergency signaling equipment that monitors Form C contact closures. If your system requires multiple independent supervised power rails or higher current capacity, evaluate the Altronix power supply line for multi-channel alternatives.
This unit is not a UPS replacement — it provides battery charging and backup power conditioning only. For mission-critical loads requiring uninterruptible AC-to-DC conversion with active power conditioning, parallel a UPS on the AC input side. For mixed-voltage deployments across access control systems, the AL400UL reduces SKU complexity and field configuration time versus single-voltage supplies.
Typical Deployments
- Access control systems (door controllers, card readers, mag locks) requiring battery backup in dual-voltage environments.
- Burglar alarm and fire signaling systems with supervised power and battery charging integrated into a single cabinet location.
- Hospital nurse call equipment and emergency signaling infrastructure where backup power is required by code and status reporting is critical to operational safety.
- Security infrastructure (gates, barriers, cameras) using mixed 12VDC and 24VDC loads with centralized battery backup and AC failure notification.
Frequently Asked Questions
Q: Can I use lithium or LiFePO₄ batteries with the AL400UL?
A: No. The AL400UL charger is designed exclusively for sealed lead acid (SLA) or gel-type batteries. Lithium chemistry requires different charge profiles and protection circuits; using incompatible battery types may damage the battery, the charger, or both.
Q: What is the maximum battery capacity the AL400UL can charge?
A: Altronix does not publish a maximum amp-hour rating in the available documentation. Consult the datasheet or contact Altronix technical support with your intended battery specifications before purchase to verify compatibility and charge time.
Q: If I select 24VDC output, why does the current rating drop to 3A instead of staying at 4A?
A: This is a power-budget constraint — the unit's internal transformer and rectifier deliver approximately 96W of DC power. At 12VDC, that yields 8A theoretical (limited to 4A for safety); at 24VDC, the same 96W yields 4A theoretical (limited to 3A). Higher voltage = lower current at fixed wattage.
Q: Does the AL400UL require a UPS on its AC input?
A: Not inherently. The AL400UL provides its own battery charging and backup conditioning. However, if your facility experiences frequent short AC outages (sub-second brownouts), a UPS upstream will prevent the AL400UL's battery from cycling repeatedly, extending battery life and reducing maintenance.
Q: What are the Form C supervision contacts used for?
A: The two Form C relay outputs signal AC Failure and Battery Low voltage events. These dry contacts can be wired to an access control panel, alarm system, or SCADA network to log power events, trigger alerts, or activate redundant systems — standard practice in life-safety and security installations.
Q: Is the AL400UL suitable for outdoor mounting?
A: The operating temperature range is 0°C to 49°C. Uncontrolled outdoor environments often exceed 49°C in summer or drop below 0°C in winter. If outdoor installation is required, house the unit in an insulated, ventilated cabinet or NEMA enclosure and verify thermal performance with Altronix before deployment.
Ted PerryPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
The Altronix AL400UL is a straightforward, no-nonsense choice for mixed-voltage access control and alarm deployments where battery backup and AC failure signaling are code-mandated. The field-selectable 12VDC/24VDC output eliminates the procurement and inventory burden of maintaining two different SKUs, which matters in large facility rollouts. That said, you need to understand the power-budget tradeoff: 4A @ 12VDC, but only 3A @ 24VDC — a real constraint if your 24VDC load is marginal.
Technical Highlights:
- Dual-voltage selector (12VDC/24VDC): Reduces SKU burden by roughly 50% in mixed-voltage environments; no need to stock separate models or redesign panel layouts when equipment arrives with a different voltage rating.
- Integrated battery charger (SLA/gel only): Charging and backup power in one chassis — no external charger, no extra AC outlet needed. Charge rate is unspecified in available docs, so test with your battery size before full deployment.
- Dual Form C supervision outputs (AC Failure + Battery Low): Two independent relay contacts allow granular status reporting to your access control or SCADA system. Battery Low especially useful for predictive maintenance — you'll get warning before backup power is consumed.
- 115VAC 60Hz input at 3.5A: Modest draw, but verify your panel's available AC capacity before adding multiple units; a 15A circuit can comfortably support 4 AL400UL units under nominal load.
Deployment Considerations:
- Battery type is locked in: SLA or gel only. No lithium support. If your facility is trending toward LiFePO₄ backup systems, this unit will not integrate without an external charger — plan accordingly.
- Operating temperature ceiling at 49°C is tight: A warm electrical closet or outdoor cabinet without climate control will exceed this. Do not assume passive cooling in dense multi-unit installations.
- Single output channel: If your access control cabinet needs multiple independent supervised rails (e.g., separate supplies for readers vs. mag locks), you'll install multiple AL400UL units or evaluate a multi-channel distribution module — cost and footprint implications apply.
Size the AL400UL for facilities deploying 2–6 access control doors, burglar/fire alarm zones, or nurse call endpoints with integrated backup. For larger campuses, consider a centralized power distribution system with multiple supervised outputs on a single shelf. For single-door or single-reader installations, this is overkill — a smaller, cheaper single-channel charger will suffice.
