Altronix MAXFIT3F Single-Output Expandable Power Supply with Battery Backup
Overview
The Altronix MAXFIT3F is a wall-mount, single-output power supply and battery charger designed for access control and surveillance installations that need reliable 12VDC or 24VDC power with automatic battery failover — all in a compact indoor enclosure. It delivers up to 6A of filtered, regulated DC output from a 120VAC/60Hz input, and accommodates up to four 12VDC/12AH sealed lead-acid or gel-type batteries internally, giving you real standby capacity without a separate battery cabinet. Browse the full Altronix power solutions line for compatible accessories and expansion options, or explore the broader security power supply category to compare form factors and output ratings.
Key Features
- Selectable 12VDC or 24VDC Output @ 6A: One unit covers the two most common DC voltages in commercial security — wire it for your access control readers, door hardware, or cameras without buying separate supplies for each voltage tier.
- Auxiliary 1A Unswitched Output: The aux output stays live regardless of the main output state, useful for powering monitoring circuits or request-to-exit devices that need continuous power even during a controlled shutdown sequence.
- Supports Up to Four Internal 12AH Batteries: Four 12VDC/12AH batteries fit inside the BC750 enclosure — no external battery cabinet needed on most mid-sized installations. That translates to meaningful standby duration when you calculate AH against your load. Batteries are sold separately.
- Instantaneous Failover on AC Loss: Switchover is immediate upon AC loss, so downstream devices — locks, cameras, controllers — see no interruption. For card-access applications where a power glitch can trigger a fail-secure or fail-safe lock state, that matters.
- Low DC Power Shutdown (Deep Discharge Protection): The unit cuts DC output terminals when battery voltage drops below approximately 71–73% (12V units) or 70–75% (24V units) of nominal. This prevents the kind of deep discharge that kills sealed lead-acid batteries prematurely and drives up maintenance costs.
- Form C Supervision Contacts for AC Failure and Battery Condition: Both AC fail and battery status report via Form C relay contacts — wire directly into your access control panel's supervised input zones for centralized alarm monitoring without adding a separate communication module.
- Fire Alarm Disconnect — Latching or Non-Latching: Configurable FAD supports both latching and non-latching modes with a 10K EOL resistor, making integration with fire alarm control panels straightforward and code-compliant on supervised loops.
- Overvoltage Protection + Filtered/Regulated Output: Clean, regulated DC protects sensitive electronics from line noise — particularly relevant when powering IP cameras or access control panels that can be damaged by voltage spikes on noisy commercial circuits.
- Operating Range 0°C to 49°C: Rated for standard indoor environments. Not suitable for unheated exterior enclosures or environments that exceed 120°F — plan accordingly for mechanical rooms or attic installations in warm climates.
Integration and Compatibility
The MAXFIT3F is compatible with the Altronix LINQ2 Network Communication Module, which adds remote monitoring and reporting of power supply diagnostics over IP — useful for large campuses where a technician can't physically check every panel. The unit is also compatible with eFlow series and MaximalF power supply/chargers within the Altronix ecosystem. For installations requiring expanded battery capacity beyond 12AH/12VDC, Altronix supports 40AH and 65AH configurations in a separate enclosure. Pair with a access control system or connect to existing NVR infrastructure for a fully monitored security power backbone. See the power planning guide for load calculation guidance on multi-door deployments.
Frequently Asked Questions
Q: How many batteries can the MAXFIT3F enclosure hold, and what type are supported?
A: The BC750 enclosure accommodates up to four 12VDC/12AH batteries. Supported types are sealed lead-acid or gel-type batteries. Batteries are sold separately.
Q: Does the MAXFIT3F support both 12VDC and 24VDC output?
A: Yes. The unit is field-configurable for either 12VDC or 24VDC output at up to 6A maximum supply current. You select the output voltage at installation — it is not dual-simultaneous output.
Q: What happens to the DC output when AC power is lost?
A: Failover to battery is instantaneous upon AC loss. Downstream devices continue to receive DC power from the installed batteries without interruption.
Q: Can the MAXFIT3F report power status to an access control panel?
A: Yes. The unit provides Form C relay contacts for both AC failure and battery condition monitoring. These can be wired into supervised input zones on most access control panels. Optional LINQ2 module adds IP-based remote diagnostics.
Q: What is the warranty on the MAXFIT3F?
A: Altronix provides a lifetime manufacturer warranty on the MAXFIT3F.
Q: Is the MAXFIT3F suitable for outdoor or unheated enclosure installations?
A: No. The unit is rated for indoor use only, with an operating temperature range of 0°C to 49°C (32°F to 120°F). Install in a conditioned or temperature-controlled space.
The MAXFIT3F is the unit I reach for on mid-sized commercial access control installs where you need genuine standby capacity without dedicating wall space to a secondary battery enclosure. The BC750 cabinet fits four 12AH batteries internally — that is a real design decision, not a spec-sheet footnote, and it simplifies rough-in considerably on crowded IDF walls.
Technical Highlights:
- 6A Regulated Output: Enough headroom for multiple door controllers and readers on a single supply. The filtered, regulated output also protects sensitive access control hardware from the line noise that plagues many commercial buildings.
- Deep Discharge Protection: The unit cuts output at 71–73% of nominal battery voltage on 12V configurations. In practice, this meaningfully extends battery service life — deep discharging is the primary failure mode for sealed lead-acid in standby applications.
- Form C Supervision Contacts: AC fail and battery status both terminate on Form C relays. On a properly supervised panel, you will get an alarm the moment AC drops or a battery goes soft — no manual inspection required between service visits.
Deployment Considerations:
- The 3.5A input draw and 5A/250V fusing mean this unit runs on a standard 15A branch circuit with comfortable margin — no dedicated circuit required on most installations, but verify your panel schedule before rough-in.
- Operating ceiling is 49°C (120°F). Mechanical rooms with poor airflow or attic-mounted panels in warm climates can exceed this — check ambient temps before specifying.
This unit is a strong fit for multi-door commercial office or healthcare installs where you want supervised power reporting, internal battery standby, and the option to add LINQ2 remote diagnostics later without replacing the hardware.
