Altronix MAXFIT55FE Dual-Output 12VDC Power Supply with Battery Backup Enclosure
Overview
The Altronix MAXFIT55FE is a dual-output, 12VDC expandable power system housed in a compact indoor enclosure — purpose-built for commercial security installations that need independently supervised power zones with local battery backup. It delivers two discrete 12VDC outputs rated at 10A each (20A combined), plus a 1A auxiliary output, all from a single 120VAC/7A input. If you're powering access control panels, alarm systems, or multi-zone camera runs that demand clean DC power with failover and supervision, the MAXFIT55FE is the configuration to reach for in the Altronix power supply line.
The enclosure is sized for indoor wall mount use at 16.5"W x 20.5"H x 6.25"D and accommodates up to four 12VDC/12AH sealed lead-acid or gel batteries internally — so you're not bolting a separate battery cabinet next to it. Batteries are sold separately, but the capacity is there to sustain loads through extended AC outages without external hardware.
Key Features
- Two Independent 12VDC @ 10A Outputs: Each output runs through its own power supply/charger module. That means a fault or overload on one zone doesn't pull down the other — relevant when you're splitting access control from cameras, or separating intrusion from intercoms on the same panel.
- 20A Total Capacity from a Single Input: Running 120VAC at 7A input and delivering 20A of 12VDC output is an efficient step-down — it keeps conduit runs simple since you're wiring one AC circuit to the enclosure instead of multiple supplies elsewhere in the rack or wall cavity.
- 1A Auxiliary Power-Limited Output: The unswitched 1A auxiliary is power-limited per NEC, which matters for installations where code distinguishes power-limited from non-power-limited wiring. Wire it to request/exit devices or sensors that require a clean, isolated rail.
- Up to Four 12AH Batteries Internal: Four 12VDC/12AH cells fit inside the enclosure without an add-on box. Larger 40AH or 65AH configurations are supported but require a separate enclosure — plan your battery runtime budget before spec'ing the enclosure size.
- Instantaneous AC Failover: On AC loss, the unit switches to battery without a delay gap. For access control applications with electric strikes or maglocks, that instantaneous transition is the difference between a door staying in its fail-secure or fail-safe state versus a momentary dropout that resets credentials or logs a nuisance alarm.
- Form C Supervision Contacts for AC Fail and Battery: Both AC failure and battery conditions report out via Form C dry contacts — wire these directly to your alarm panel or monitoring system for remote supervision without needing a separate network module. If you need IP-based diagnostics, the optional LINQ2 module (sold separately) adds network monitoring and reporting.
- Low Battery Shutdown at 71–73% of 12V: The unit cuts DC output terminals before the batteries reach deep-discharge territory. That threshold protects sealed lead-acid cells from premature capacity loss — a commonly skipped spec that adds years to battery service life in practice.
- Fire Alarm Disconnect: Supervised fire alarm disconnect with selectable latching or non-latching mode and a 10K EOL resistor. That's a requirement in many AHJ-reviewed installations and eliminates the need for a separate relay or relay board.
- Filtered and Regulated Output with Over Voltage Protection: Non-power-limited outputs are filtered and regulated with OVP — sensitive electronics on the load side (IP cameras, card readers, intercoms) won't see voltage spikes from load switching or battery transitions.
- Operating Range 0°C to 49°C (32°F to 120°F): Covers IDF closets, security rooms, and mechanical spaces that aren't climate-controlled. Storage tolerance extends to -20°C / 70°C, so pre-staged units sitting in an unheated warehouse aren't a concern.
- 123 BTU/Hr Heat Dissipation: At full load, the enclosure throws about 123 BTU/hr. In a small, poorly ventilated closet housing multiple enclosures, that adds up — account for it during site thermal planning, especially in warm climates where the 49°C upper limit can be approached in summer without HVAC.
Integration and Compatibility
The MAXFIT55FE sits in the broader Altronix power supply ecosystem and is compatible with the optional LINQ2 network communication module for remote monitoring, control, and diagnostics over IP. For installations requiring integration with access control or alarm panels, the Form C supervision contacts connect directly to standard panel inputs — no proprietary protocol required. When provisioning battery backup, use sealed lead-acid or gel-type 12VDC/12AH cells; flooded or AGM cells with different charge profiles are not called out in the evidence and should be verified with Altronix before substituting. If your site has extended runtime requirements beyond what four internal batteries provide, plan for a separate battery backup enclosure alongside the MAXFIT55FE — Altronix supports 40AH and 65AH external configurations. For power planning on multi-zone access control deployments, factor in inrush current from electric strikes and maglock coils against the 10A-per-output rating; sustained draw at or near 10A on a single rail leaves no headroom for load spikes.
Frequently Asked Questions
Q: How many batteries can the MAXFIT55FE enclosure hold internally?
A: The enclosure accommodates up to four 12VDC/12AH sealed lead-acid or gel-type batteries internally. Batteries are sold separately. Larger battery configurations (40AH or 65AH) require a separate enclosure.
Q: What happens when AC power fails on the MAXFIT55FE?
A: Failover to battery backup is instantaneous upon AC loss. The unit also reports AC failure via Form C dry-contact supervision outputs, which can be wired to an alarm panel or monitoring system.
Q: What is the total DC output capacity of the MAXFIT55FE?
A: The unit provides two independent 12VDC outputs rated at 10A each (20A combined), plus an unswitched auxiliary power-limited output rated at 1A — all derived from a single 120VAC/60Hz, 7A input.
Q: Does the MAXFIT55FE protect against deep battery discharge?
A: Yes. The unit monitors battery voltage and shuts down DC output terminals when voltage drops below 71–73% of nominal 12V, preventing deep discharge that degrades sealed lead-acid and gel battery capacity over time.
Q: Can the MAXFIT55FE be monitored remotely over a network?
A: The base unit supervises via Form C dry contacts for AC failure and battery conditions. For IP-based remote monitoring, diagnostics, and control, the optional LINQ2 network communication module integrates with the MAXFIT55FE.
Q: What is the warranty on the Altronix MAXFIT55FE?
A: Altronix provides a lifetime warranty on the MAXFIT55FE, as stated on the manufacturer's product page.
The MAXFIT55FE is the unit I spec when a site needs dual independent 12VDC rails with internal battery backup and panel-ready supervision — all in a single wall-mount footprint. The 20A combined output (two independent 10A rails) with instantaneous battery failover gives you real redundancy between load zones, not just more amperage on a shared bus. That distinction matters in commercial access control where a shared supply can take down card readers and cameras simultaneously on a single overcurrent event.
Technical Highlights:
- Dual Independent 10A Outputs: Each rail runs through its own power supply/charger module — a fault on one zone doesn't cascade to the other, which is the architecture you want when separating access control from camera power in the same enclosure.
- Low Battery Shutdown at 71–73% of 12V: The cutoff threshold actively protects sealed lead-acid and gel cells from deep discharge, extending battery replacement intervals in installations where batteries may sit lightly loaded for months at a time.
- Form C Supervision on Both AC Fail and Battery: Dry-contact outputs for both AC failure and battery status connect directly to any standard alarm panel input — no proprietary protocol, no extra board, no software configuration required for basic supervision.
Deployment Considerations:
- The enclosure holds up to four 12AH batteries internally, but batteries are sold separately — build battery cost into your BOM from the start and verify cell dimensions fit the enclosure before purchasing third-party cells.
- At full load, the unit dissipates 123 BTU/hr. In small, enclosed security closets with multiple enclosures, thermal accumulation against the 49°C operating ceiling is a real constraint — verify room cooling before stacking units.
The MAXFIT55FE is the right call for mid-size commercial buildings — schools, medical offices, multi-tenant retail — where a single compact enclosure needs to carry independently supervised power zones with internal battery backup and fire alarm disconnect without running conduit to a separate battery cabinet or relay board.
