Altronix AL201UL 12VDC Power Supply with Integrated Battery Charger
The Altronix AL201UL is a regulated 12VDC power supply and integrated battery charger designed for security infrastructure requiring continuous operation during AC mains loss. Operating from 24VAC input, the AL201UL delivers up to 0.75A of regulated 12VDC output, making it suitable for access control panels, alarm systems, gate operators, and distributed surveillance power nodes in multi-tenant or remote deployments. The unit combines power supply and automatic battery charging in a single compact enclosure, reducing wiring complexity and eliminating the need for separate charging circuits.
Key Features
- Regulated 12VDC output at 0.75A continuous current — sufficient for most small access control readers, alarm panels, or single-camera power nodes without requiring a larger supply or PoE infrastructure upgrade. The 0.75A limit means you'll need to account for total device loads in advance to avoid undersizing.
- Integrated battery charger with automatic failover — when AC mains power is present, the AL201UL charges an external 12VDC battery; when AC drops, the battery automatically becomes the load supply. No manual switching or additional relays required.
- AC Fail supervision — detects loss of primary AC input and signals the connected device (typically a security panel or monitoring station) of the outage. Useful for logging power events and triggering backup actions in control panels.
- Low Battery supervision — monitors battery voltage and alerts the system if backup capacity falls below usable levels. Prevents silent failures where a depleted battery would leave the system unprotected during a second outage.
- 24VAC input with internal transformer-based regulation — accepts standard building 24VAC (common in security wiring) and steps down to precisely regulated 12VDC. The transformer design is inherently more robust to voltage fluctuations than switching supplies in older installations.
- Single output connector — minimizes connection points and reduces field assembly errors during installation.
- UL Listed certification — meets code requirements for most jurisdictions; necessary for permitted security system installations and insurance compliance.
- Lifetime Limited Warranty — covers defects in materials and workmanship, though this typically applies to the supply itself, not external batteries.
Deployment Considerations
The AL201UL is sized for small-to-medium security nodes, not for powering entire camera racks or multi-door access control systems. At 0.75A output, you can support roughly one standard electronic lock, a basic alarm panel, or a low-power remote I/O module, but not multiple devices simultaneously without careful load planning. The 24VAC input requirement means you must have 24VAC wiring already present on site — if your facility uses only 120VAC, you'll need a separate 24VAC transformer upstream.
Battery selection is critical. The AL201UL charges any external 12VDC lead-acid or sealed AGM battery; common choices are 7Ah to 18Ah units mounted in adjacent cabinets or wall enclosures. Do not over-specify battery capacity assuming unlimited runtime — larger batteries take longer to charge and may exceed the charger's current output, leaving the system vulnerable to rapid outages.
The supervision functions (AC Fail and Low Battery) output contact closures to the connected device — verify that your alarm panel, access control unit, or monitoring device supports these inputs before ordering. Some legacy panels do not monitor external power loss signals, limiting the benefit of the supervision features.
Physical Specifications
Enclosure dimensions are 8.5" W × 7.5" H × 3.5" D (215.9mm × 190.5mm × 88.9mm), making it suitable for wall mounting or installation inside a small cabinet. Operating temperature range is 0°C to 49°C (32°F to 120°F), so outdoor or unheated installations in cold climates may see performance degradation — verify the battery backup charging rate is acceptable for your expected winter operating temperatures.
When to Choose a Different Model
If you require higher output current (e.g. multiple cameras or larger door systems), consider a higher-amperage supply in the Altronix PowerSeries line. If your facility has no 24VAC supply and adding one is cost-prohibitive, a 120VAC-input supply may be more practical. For systems demanding true uninterruptible power with surge protection and conditioning, a dedicated UPS-class backup supply may be warranted, though those carry significantly higher cost and complexity.
Frequently Asked Questions
Q: What battery types does the AL201UL support?
A: The AL201UL charges any standard 12VDC lead-acid or sealed AGM (absorbed glass mat) battery. Capacity typically ranges from 7Ah to 18Ah depending on your runtime requirements and the charging current available from the supply.
Q: How long will the battery back up the system during an outage?
A: Runtime depends entirely on battery capacity and total device current draw. For example, a 12Ah battery powering a 0.5A load provides roughly 24 hours of backup. Calculate runtime by dividing battery amp-hours by your connected device current in amps.
Q: Does the AL201UL work with 120VAC input, or do I need 24VAC?
A: The AL201UL requires 24VAC input only. If your facility has only 120VAC available, you will need to install a separate 24VAC transformer upstream of the AL201UL, or select a different model rated for 120VAC input.
Q: What do the supervision contact closures control?
A: The AC Fail and Low Battery contacts output dry relay closures suitable for connecting to alarm panels, fire systems, or monitoring stations. Verify that your connected device supports these inputs — not all legacy systems do.
Q: Is the AL201UL suitable for outdoor installations?
A: The operating temperature range of 0°C to 49°C (32°F to 120°F) supports outdoor use, but the unit itself is not weatherproof. It must be mounted in a lockable enclosure, wall cabinet, or weatherproof box with ventilation to prevent moisture ingress and overheating in direct sunlight.
Q: What is the warranty coverage?
A: The AL201UL includes a Lifetime Limited Warranty covering defects in materials and workmanship of the supply unit itself. External batteries and custom enclosures are not included in this warranty.
Ted PerryPerspective based on aggregated and affiliated engineering team experience.
The Altronix AL201UL is a straightforward and reliable choice for distributed security power nodes where 24VAC is already available and battery backup is a hard requirement. At 0.75A output, it's not a power-hungry device, which means it integrates cleanly into access control cabinets, gate operators, and remote alarm repeater stations without requiring oversized batteries or long charging cycles. The integrated charger and AC Fail supervision are the real wins here — they eliminate field assembly of relay logic and provide automatic failover that most small systems lack.
Technical Highlights:
- 0.75A continuous output at 12VDC: Sufficient for a single electronic lock, access reader, or alarm panel. Ensure total load doesn't exceed this; exceeding it will cause the supply to fold back or thermally protect, leaving devices without power. This is not a limitation of the AL201UL itself — it's correct for the application — but undersizing your load estimate is a common field mistake.
- Integrated battery charger with automatic transition: The charger supplies the load directly from AC mains and simultaneously trickle-charges the battery. When AC fails, the battery becomes the primary supply with no switching delay. This architecture is more reliable than relay-based manual switchovers because there's no moving contact to stick.
- AC Fail and Low Battery supervision: Both output dry-contact closures (not isolated logic signals). The AL201UL does not condition or buffer these signals — they're simple, which means they're fast and reliable, but they require clean inputs on the receiving panel. If your panel has noisy power signals, you may see false alarms on the Low Battery contact.
- 24VAC transformer-based regulation: More robust to brownouts and extended voltage sag than a switching-mode design. If your facility has weak 24VAC (e.g. 18VAC nominal), the AL201UL will still regulate to 12VDC, but the battery charge rate may drop because the charger circuit has less overhead voltage to work with.
Deployment Considerations:
- Battery selection is non-trivial: A 7Ah lead-acid battery charges in roughly 6–8 hours at the AL201UL's trickle rate. If you have frequent short outages and the battery never fully recovers between them, you'll eventually lose backup capacity. Size the battery conservatively and verify the charge time fits your power grid reliability profile.
- Supervision contact wiring must be verified: The AC Fail and Low Battery outputs are contact closures only. Legacy alarm panels may not have inputs for external power loss signals, or may require specific wiring logic (normally open vs. normally closed). Test this integration on a bench before deploying to a live site.
- Operating temperature floor of 0°C affects charging in winter: Below 0°C, lead-acid batteries accept almost no charge current. If your AL201UL is mounted in an unheated cabinet in a cold climate, winter runtime will degrade unless you add thermal management or use a lower-temperature-rated battery.
The AL201UL is the correct choice for a single-node backup power scenario — a gate operator house, a remote door strike, or an outbuilding alarm repeater. It is not oversized and not under-featured for those use cases. If you're powering multiple doors or a full security panel with multiple readers, step up to a higher-amperage supply in the Altronix PowerSeries family. If your facility lacks 24VAC infrastructure, solving that wiring problem upstream is worth the time investment rather than forcing a 120VAC-to-24VAC conversion for one supply.
