Altronix MAXFIT75E Dual-Voltage Expandable Power Supply with Battery Backup
The Altronix MAXFIT75E is a dual-output expandable power system engineered for commercial security installations that require simultaneous 12VDC and 24VDC power delivery — without compromise on either rail. Housed in a wall-mount BC750 enclosure with room for up to four 12VDC/12AH batteries, this unit is purpose-built for access control, camera, and mixed-device deployments where redundancy and supervision are non-negotiable. If you're specifying power for a panel room or IDF closet and you need both voltage rails with real failover and fault reporting, the MAXFIT75E belongs on your bill of materials.
Overview
At its core, the MAXFIT75E houses two independent single-output power supply/charger modules — one delivering 12VDC @ 10A, the other 24VDC @ 10A — operating simultaneously from a 115VAC/60Hz/7.0A input. This isn't a shared-output unit that splits capacity across rails: each output is independently regulated and filtered, meaning your 24VDC access control hardware won't starve when the 12VDC camera load spikes. The enclosure fits neatly on any interior wall, measuring 16.5"W × 20.5"H × 6.25"D, and weighs 21.2 lbs. — substantial but manageable for two-person installation on standard wall blocking.
Browse the full Altronix power supply lineup to compare additional expandable and distributed power options for your project.
Key Features
- Dual Independent Rails — 12VDC @ 10A and 24VDC @ 10A: Each rail runs at full 10A capacity without sharing headroom with the other. A mixed panel room running 24VDC magnetic locks alongside 12VDC cameras no longer requires two separate power supplies — one enclosure handles both loads cleanly.
- Instantaneous Failover on AC Loss: When AC input drops, the unit switches to battery immediately — no brownout gap, no device reset. For card readers, door strikes, and access panels, this means the site stays operational through a grid event without a controlled shutdown sequence.
- Battery Supervision via Form C Contacts: The MAXFIT75E monitors battery presence and charge state and reports via dry Form C contacts. Wire these contacts to your access control panel or monitoring receiver and you'll get a discrete alert when a battery disconnects or discharges below threshold — before a power event exposes the gap.
- AC Failure Supervision via Form C Contacts: Separate Form C contacts report AC loss independently from battery status. This lets you distinguish between a utility outage (AC fault, batteries good) and a degraded-battery condition — two very different service priorities.
- Enclosure Holds Up to Four 12VDC/12AH Batteries: The BC750 enclosure accommodates up to four 12AH sealed lead-acid or gel-type batteries internally, for up to 48AH of on-board reserve. For longer standby requirements (40AH or 65AH), a separate external enclosure is supported — plan for that before closeout if the AHJ mandates 24-hour or 60-hour backup.
- Over-Voltage Protection, Filtered and Regulated Output: Both rails include over-voltage protection and active filtering. Sensitive access control electronics and IP cameras are protected from transient spikes that could corrupt flash storage or reset microcontrollers mid-event.
- Three-LED Status Panel (AC Input, DC Output, Battery): The front panel gives any technician an immediate visual read: green AC present, DC output powered, and battery status (discharged or disconnected). No multimeter needed for a first-pass health check during commissioning or a service call.
- 5A/250V Fusing: The input fuse at 5A/250V is a replaceable, field-serviceable component. When a fault blows the fuse, a trained technician can restore the unit in the field without swapping the entire assembly — a meaningful service-cost difference on a multi-year maintenance contract.
- Operating Range 0°C to 49°C (32°F to 120°F): Covers typical indoor mechanical room and IDF closet environments. The 49°C ceiling is worth checking against your closet's peak summer temperature if it's an unconditioned space — HVAC failure in a hot climate can push a sealed room past this limit.
- Thermal Dissipation 184 BTU/Hr.: With both rails fully loaded, the unit pushes roughly 184 BTU/Hr. Factor this into your room heat load calculation, especially if you're stacking multiple MAXFIT units in a small enclosure room.
Integration & Compatibility
The MAXFIT75E is designed for integration into commercial security power supply architectures. The Form C dry-contact outputs on both the AC failure and battery supervision circuits are compatible with virtually any access control panel or central station receiver that accepts normally-open/normally-closed trouble inputs — Altronix does not lock you into a proprietary monitoring topology. The dual-voltage output is particularly well-suited to mixed installations: 24VDC for electrified hardware (strikes, maglocks, readers) and 12VDC for IP cameras or ancillary devices powered off the same panel room. Battery selection is open: any sealed lead-acid or gel-type 12VDC/12AH battery fits within the enclosure capacity — source locally or specify a brand you have under existing maintenance agreements. For projects requiring a complete access control power solution, pair this unit with your door hardware and panel to eliminate a second supply entirely. If standby runtime requirements exceed what four internal batteries provide, Altronix supports expansion to separate battery enclosures supporting up to 40AH or 65AH configurations.
Frequently Asked Questions
Q: Can the MAXFIT75E supply 12VDC and 24VDC at the same time, or is it one or the other?
A: Both rails operate simultaneously and independently. The unit delivers up to 10A on the 12VDC rail and up to 10A on the 24VDC rail at the same time — each output is a separate regulated supply/charger module within the same enclosure.
Q: What batteries are compatible with the MAXFIT75E, and how many fit in the enclosure?
A: The enclosure accommodates up to four 12VDC/12AH sealed lead-acid or gel-type batteries, providing up to 48AH of on-board reserve capacity. Batteries are sold separately. For larger standby requirements (40AH or 65AH), a separate external battery enclosure is required.
Q: How does the MAXFIT75E notify me of an AC failure or battery problem?
A: The unit provides separate Form C dry-contact outputs for AC failure supervision and battery supervision. These contacts wire directly to your access control panel or monitoring receiver to generate discrete trouble alerts. LED indicators on the front panel also show real-time status of AC input, DC output, and battery condition.
Q: What is the warranty on the MAXFIT75E?
A: Altronix provides a lifetime warranty on the MAXFIT75E.
Q: What are the physical dimensions and weight of the MAXFIT75E enclosure?
A: The BC750 wall-mount enclosure measures 16.5" W × 20.5" H × 6.25" D and weighs approximately 21.2 lbs. (9.6 kg). Shipping weight is 26.6 lbs. (12.1 kg).
Q: Can I use the MAXFIT75E in an unconditioned utility closet?
A: The operating temperature range is 0°C to 49°C (32°F to 120°F). Most conditioned interior spaces fall within this range, but verify your closet's peak summer temperature — an unconditioned mechanical room in a hot climate can exceed 49°C during HVAC outages, which is outside the rated operating envelope.
The MAXFIT75E is the unit I spec when a project has both 24VDC electrified hardware and 12VDC cameras sharing the same panel room and the designer wants one supply entry on the BoM instead of two. The simultaneous dual-rail architecture — 10A on each output, independently regulated — means neither load competes for headroom, and the instantaneous battery failover protects door strikes and card readers through grid events without a restart cycle.
Technical Highlights:
- Dual 10A Independent Rails: 24VDC @ 10A and 12VDC @ 10A run simultaneously from a single 115VAC/7.0A input — no shared current pool, no rail-to-rail interference on transient loads.
- Form C Supervision Contacts (AC + Battery): Two separate sets of Form C dry contacts give you discrete trouble signals for AC failure and battery fault. Wire these to any panel with a normally-closed supervision input and you get differentiated alarm categories — utility outage vs. degraded battery — without custom firmware or additional monitoring modules.
- Four-Battery Internal Capacity: The BC750 enclosure holds up to four 12VDC/12AH sealed lead-acid or gel cells — up to 48AH on-board. For most access control holdover requirements (4–8 hours at partial load), four internal batteries is sufficient; for 24-hour AHJ mandates at heavier loads, price out the external enclosure option at spec time, not during AHJ inspection.
Deployment Considerations:
- At full dual-rail load, the MAXFIT75E dissipates approximately 184 BTU/Hr. — account for this in your panel room heat load calculation before stacking multiple units in a small IDF closet without supplemental cooling.
- The 49°C (120°F) operating ceiling is tight for unconditioned mechanical rooms in warm climates. If the room loses HVAC seasonally, measure peak ambient temperature before commissioning — the unit is not rated for operation above that threshold.
For a mid-size commercial office or campus building with mixed access control and camera infrastructure — where the electrical room is conditioned and the AHJ requires supervised battery backup — the MAXFIT75E consolidates your power architecture cleanly and gives the service tech a three-LED front panel that makes health checks fast during quarterly inspections.
