Altronix MAXFIT75FE Dual-Output Expandable Power Supply with Battery Backup

Overview

The Altronix MAXFIT75FE is a dual-output, UPS-capable power supply/charger system designed for access control and security installations that demand simultaneous 12VDC and 24VDC distribution without deploying two separate enclosures. Drawing 120VAC at 8A, the MAXFIT75FE delivers 12VDC @ 10A and 24VDC @ 10A concurrently — enough headroom to power a mid-size access control panel, door strikes, card readers, and ancillary devices from a single wall-mount box. The BC750 enclosure accommodates up to four 12VDC/12AH batteries internally, giving you meaningful standby runtime without external battery cabinets cluttering the IDF closet.

Browse the full Altronix power supply and access control lineup to compare enclosure sizes and output configurations across the MaxFit family.

Key Features

• Dual 10A Outputs (12VDC and 24VDC simultaneously): Most single-supply installs force a compromise — run everything at 12V or step up to 24V and use converters. The MAXFIT75FE eliminates that trade-off: 10A per rail gives you enough current for a full door controller plus electric strikes and readers on a single supply. If your panel runs 24VDC and your strikes run 12VDC, this unit handles both natively.
• Up to Four 12AH Internal Batteries: The BC750 enclosure holds 4 × 12VDC/12AH batteries internally. That's 48AH of standby capacity on-board — enough to sustain a typical access control door group through a multi-hour outage without a separate battery enclosure. Batteries are sold separately, so you spec what the job requires rather than paying for capacity you don't need.
• Instantaneous AC Failover: Upon AC loss, switchover to battery is instantaneous. For access control applications, this matters — a delay during failover can momentarily drop a magnetic lock and log a false alarm or grant unintended egress. There is no detectable gap in DC output when mains power fails.
• Supervised Fire Alarm Disconnect (Latching or Non-Latching): The unit supports a supervised fire alarm disconnect — configurable as latching or non-latching — with a 10K EOL resistor. This means the MAXFIT75FE can be wired into a fire alarm loop and will cut DC power to door-hold devices on alarm, satisfying life-safety code requirements without an external relay module.
• Form C Supervision Contacts for AC Failure and Battery: Both the AC failure condition and battery condition report via Form C dry contacts. Wire these into your alarm panel or BMS and you get remote monitoring of power health without polling the unit — a straightforward way to meet the supervision requirements on UL-listed installations.
• Deep Discharge Prevention: The unit shuts down DC output terminals if battery voltage drops below 71–73% (12V units) or 70–75% (24V units). This protects sealed lead-acid batteries from deep discharge damage that would otherwise cut standby life from years to months — an often-overlooked spec that has real impact on total cost of ownership in battery-backed installations.
• Auxiliary Power-Limited Output @ 1A: A separate unswitched, power-limited 1A auxiliary output is available for powering low-current peripherals like request-to-exit sensors or status indicators — devices that shouldn't share a rail with higher-current strikes or controllers.
• Over-Voltage Protection, Filtered and Regulated Output: The DC rails are filtered and regulated with over-voltage protection. Card readers and access control panels are sensitive to voltage spikes; clean, regulated DC prevents false reads and protects controller electronics on long wire runs.
• LINQ2 Network Communication Module Compatible: The MAXFIT75FE is compatible with the optional LINQ2 module, which adds network-based monitoring of power supply diagnostics. For enterprise deployments with centralized infrastructure monitoring, LINQ2 lets you check supply status, battery health, and alarm conditions remotely — without dispatching a technician to the IDF.

Integration and Compatibility

The MAXFIT75FE is built around Altronix's eFlow series power supply/charger modules (eFlow102NB and eFlow104NB), which slot into the BC750 enclosure. Fuse ratings are matched to the module installed: 5A/250V for the eFlow102NB and 6.3A/250V for the eFlow104NB. The enclosure's wall-mount design suits server closets, electrical rooms, and secured utility spaces where floor space is at a premium.

For installations requiring network-supervised access control power supplies, the optional LINQ2 module (sold separately) integrates with Altronix's LINQ user portal for remote diagnostics. Pair this unit with a compatible access control system — the dual-voltage output makes it well-suited for mixed-technology deployments where both 12V and 24V devices are present on the same door group.

Need to plan battery runtime for your specific load? Altronix's online battery/load calculator is a practical pre-design tool for sizing the number and capacity of batteries before you commit to an enclosure size. Review our power supply selection guide for guidance on matching output current, battery capacity, and supervision requirements to your project scope. If your installation requires PoE-based power distribution alongside DC power, pair with a PoE switch for IP device power.

Frequently Asked Questions

Q: Can the MAXFIT75FE supply 12VDC and 24VDC at the same time?

A: Yes. The MAXFIT75FE runs two independent power supply/charger modules — one providing 12VDC @ 10A and one providing 24VDC @ 10A — simultaneously. Both rails are active concurrently, so you can power 12V and 24V devices from a single enclosure without any switching or manual reconfiguration.

Q: Are batteries included with the MAXFIT75FE?

A: No. Batteries are sold separately. The BC750 enclosure accommodates up to four 12VDC/12AH sealed lead-acid or gel-type batteries internally. For higher battery capacity (40AH or 65AH), a separate external enclosure is required.

Q: What is the warranty on the MAXFIT75FE?

A: Altronix offers a Lifetime Warranty on the MAXFIT75FE, as stated on the manufacturer's product page.

Q: Does the MAXFIT75FE support fire alarm integration?

A: Yes. The unit includes a supervised fire alarm disconnect that can be configured as latching or non-latching, with a 10K EOL resistor. This allows the MAXFIT75FE to be integrated into a fire alarm loop so that DC output to door-hold devices is cut on alarm, in compliance with life-safety code requirements.

Q: Can I monitor the MAXFIT75FE remotely over a network?

A: Yes, with the optional LINQ2 Network Communication Module (sold separately). LINQ2 is compatible with the eFlow series and MaximalF power supply/chargers used in the MAXFIT75FE and provides remote monitoring, control, and reporting of power supply diagnostics via the Altronix LINQ user portal.

Q: What happens to the DC output when AC power fails?

A: Failover to battery is instantaneous upon AC loss. The unit's Form C supervision contacts simultaneously signal the AC failure condition to a connected alarm panel or BMS. DC output to connected devices is maintained without interruption as long as battery charge permits.

Jerry Tildsen

The MAXFIT75FE is the unit I reach for on mid-size commercial access control jobs where the door schedule mixes 12V and 24V devices — electric strikes, maglocks, readers, REX sensors — and the customer wants everything in one enclosure rather than two separate supplies crammed into the same closet. The dual 10A rails handle the load comfortably, and the four-battery bay inside the BC750 enclosure gives you real standby capacity without bolting on a secondary battery cabinet.

Technical Highlights:

• Dual 10A Rails (12VDC + 24VDC simultaneous): Both rails are live at the same time — you're not toggling between voltages. At 10A each, you have enough headroom for a full door controller group plus ancillary devices on each rail without approaching the current limit under normal load.
• Deep Discharge Cutoff (71–75% threshold): The unit shuts DC output terminals before battery voltage craters — 71–73% for 12V, 70–75% for 24V. In practical terms, this stops the batteries from being damaged by deep discharge during extended outages, which is the main reason sealed lead-acid batteries fail prematurely in access control applications.
• Instantaneous AC Failover + Form C Supervision: Switchover is instantaneous — no gap in DC output that could momentarily drop a maglock or log a spurious alarm. The Form C contacts for AC failure and battery condition wire directly into your alarm panel, so supervision is handled at the relay level without any additional modules.

Deployment Considerations:

• The BC750 enclosure is wall-mount, sized at 16.5″W × 20.5″H × 6.25″D and weighing 21.2 lbs without batteries. Plan your wall backing and clearance carefully — four 12AH batteries add significant weight, and the 6.25″ depth requires adequate standoff from conduit runs behind the panel.
• Batteries are sold separately and the unit supports sealed lead-acid or gel type only — verify battery chemistry before sourcing. If you need 40AH or 65AH capacity, those configurations require a separate external enclosure; the BC750 maxes out at 4 × 12AH internally.

This supply is a strong fit for multi-technology access control deployments in commercial office buildings or campus facilities — particularly where a single IDF closet needs to power both 24VDC panel hardware and 12VDC door hardware off one supervised, battery-backed source, with the option to add LINQ2 for facility-wide power monitoring over the network.