Altronix MAXFIT77F Dual-Output 24VDC Power Supply with Battery Backup
Overview
The Altronix MAXFIT77F is a dual-output, 24VDC centralized power solution built for commercial access control and surveillance installations where redundancy and supervision are non-negotiable. Housed in the BC750 wall-mount enclosure, it delivers two independent 24VDC @ 10A outputs — 20A of combined capacity — alongside battery backup, Form C supervision contacts, and fire alarm disconnect, all from a single compact footprint. If you are sizing power for a multi-door access control panel or a cluster of 24V cameras and need clean, monitored DC with battery failover in one box, this is the product to evaluate from the Altronix power supply line.
Key Features
- Dual 24VDC @ 10A Outputs (20A Combined): Two fully independent power supply/charger modules each rated at 10A give you the flexibility to separate loads — run panel hardware on one output and locking devices on the other — reducing single-point failure risk across your access control power infrastructure.
- 120VAC / 9A Input, Filtered and Regulated: Draws 9A from a standard 120VAC 60Hz circuit. Regulated, filtered DC output protects downstream electronics from line noise and transient voltage spikes — relevant when running sensitive card readers or IP-based controllers.
- Battery Backup with Low-Battery Shutdown: Supports up to four 12VDC/12AH sealed lead-acid or gel batteries within the enclosure (batteries sold separately), providing localized UPS-style failover the instant AC drops. The low-battery shutdown threshold at 70–75% of 24V prevents deep discharge, extending battery service life and reducing replacement costs over a multi-year deployment.
- Form C AC Failure and Battery Supervision Contacts: Dedicated Form C dry contacts for both AC failure and battery status integrate directly with panel alarm inputs or a building management system — no guesswork on power health during an audit or after a utility event. Pair with the optional LINQ2 network module for remote SNMP-style diagnostics.
- Auxiliary 1A Power-Limited Output: An unswitched 1A auxiliary output handles ancillary loads such as REX sensors or small panel accessories without tapping into your primary 10A rails — keeps your load accounting clean.
- Fire Alarm Disconnect — Latching or Non-Latching: Supervised fire alarm disconnect with 10K EOL resistor meets code requirements in commercial installations where locking hardware must release on alarm. Configurable latching or non-latching behavior covers both fail-safe and fail-secure scenarios.
- BC750 Wall-Mount Enclosure — Indoor, 16.5"W x 20.5"H x 6.25"D: The steel BC750 enclosure mounts directly to a wall stud bay. At 21.7 lbs product weight, plan for a two-person hang during rough-in. The 6.25" depth accommodates up to four 12AH batteries internally, eliminating a separate battery cabinet in most installs.
- Over-Voltage Protection: Output OVP circuitry prevents voltage excursions from damaging downstream devices — important when the load includes microprocessor-based access control hardware with tight voltage tolerances.
Integration & Compatibility
The MAXFIT77F is designed for integration with Altronix's broader ecosystem. The optional LINQ2 network communication module (sold separately) enables remote monitoring and diagnostics over IP, compatible with Altronix eFlow and MaximalF series platforms. Form C supervision outputs connect to virtually any access control panel with alarm input terminals. For larger battery capacity requirements — 40AH or 65AH configurations — Altronix supports separate enclosure expansion, which requires purchasing a separate battery enclosure outside this unit. Review your access control system panel's input current budget against the 10A per-output rating before finalizing load calculations; panels with extensive reader and REX loads can push close to the rail ceiling when door counts scale up. Consult the power supply selection guide for multi-output load planning on larger deployments.
Frequently Asked Questions
Q: How many batteries does the MAXFIT77F support internally?
A: The BC750 enclosure accommodates up to four 12VDC/12AH sealed lead-acid or gel-type batteries. Batteries are sold separately. Larger capacity configurations (40AH or 65AH) require a separate external enclosure.
Q: What is the warranty on the MAXFIT77F?
A: Altronix provides a lifetime warranty on the MAXFIT77F per manufacturer documentation.
Q: Can the MAXFIT77F be monitored remotely over a network?
A: Yes, with the optional LINQ2 network communication module (sold separately). LINQ2 enables remote control, monitoring, and reporting of power supply diagnostics and is compatible with Altronix eFlow and MaximalF series platforms.
Q: What happens to the DC outputs when AC power is lost?
A: Failover to battery backup is instantaneous upon AC loss. The unit continues supplying 24VDC from the installed batteries. A Form C contact activates to signal AC failure to the connected panel or monitoring system.
Q: What is the low-battery shutdown threshold?
A: The MAXFIT77F shuts down DC output terminals when battery voltage drops to 70–75% of the 24V nominal level, preventing deep discharge and extending battery service life.
Q: What is the operating temperature range for the MAXFIT77F?
A: The unit is rated for 0°C to 49°C (32°F to 120°F) operating temperature. For indoor wall-mount installations in conditioned or semi-conditioned spaces, this range covers the vast majority of commercial environments.
The MAXFIT77F earns its place in commercial access control closets specifically because of its dual independent 10A rails — not just the combined 20A headroom, but the ability to isolate panel logic from locking hardware on separate outputs. That separation matters when you are troubleshooting a load fault and do not want to drop an entire door bank to isolate one circuit. I have specified this unit on mid-size multi-door installs where a single-output supply would have required either a second enclosure or careful load derating.
Technical Highlights:
- Dual 10A @ 24VDC Rails: Independent power supply/charger modules on each output mean a fault or overcurrent condition on one rail does not necessarily take down the other — a meaningful reliability argument on installations where uptime SLAs matter.
- Four-Battery Internal Capacity (12VDC/12AH each): Up to 48AH of sealed lead-acid or gel backup fits inside the BC750 without a satellite cabinet. For a typical 24V access control load of 3–5A, that translates to 8–15+ hours of runtime depending on battery condition and load mix.
- Form C Supervision on Both AC and Battery: Dry contacts for both failure modes wire directly to most panel alarm inputs. Combined with the optional LINQ2 module, you get network-visible power health — useful during quarterly testing or post-storm recovery checks without physically visiting the IDF.
Deployment Considerations:
- At 21.7 lbs without batteries, plan for a two-person installation during rough-in — each 12AH battery adds approximately 8–9 lbs, so a fully loaded enclosure approaches 55–60 lbs on the wall. Verify your mounting substrate (stud spacing, drywall anchor rating) before scheduling the hang.
- The 246 BTU/Hr heat dissipation rating at full 24VDC load is real — in a sealed IDF closet with limited airflow, that thermal output can push ambient temperatures toward the 49°C operating ceiling. If the closet runs warm, factor this into your HVAC or ventilation planning before signing off on the location.
The MAXFIT77F is the right spec for a 4–8 door commercial access control installation where the owner wants supervised battery backup, fire alarm disconnect compliance, and eventual remote monitoring via LINQ2 — all in a single wall-mount enclosure without a separate battery cabinet.
