Altronix MAXFIT77E Dual 24VDC Expandable Power Supply System
Overview
The Altronix MAXFIT77E is a dual-output expandable power system engineered for commercial security installations that need reliable, supervised 24VDC distribution with integrated battery backup. Housed in a wall-mount BC750 enclosure measuring 16.5"W x 20.5"H x 6.25"D, the MAXFIT77E runs two independent 24VDC @ 10A power supply/chargers simultaneously — giving integrators the headroom to power access control readers, door hardware, and surveillance devices from a single managed power point. Altronix carries a lifetime manufacturer warranty on this product line, which matters on infrastructure components you cannot easily swap in a live facility.
Key Features
- Dual 24VDC @ 10A Outputs: Two fully independent outputs each delivering up to 10A at 24VDC. Separate circuits mean an overload on one load group does not pull down the other — critical when access control and door strikes share the same enclosure with surveillance power.
- 115VAC / 8.8A Input with 5A/250V Fusing: Draws 8.8A from a standard 115VAC 60Hz circuit. The 5A/250V fuse provides primary protection without requiring a dedicated high-amperage branch — verify your panel allocation before commissioning.
- Instantaneous AC Failover: On AC loss, the system switches to battery without a detectable gap. For door-lock hardware and access panels that lose state on power interruption, this is the spec that keeps doors behaving correctly during an outage.
- Four-Battery Internal Capacity (12VDC/12AH each): The enclosure accommodates up to four 12VDC/12AH sealed lead-acid or gel batteries internally. Four batteries in series/parallel configuration extends runtime meaningfully on larger loads — and the design supports up to 40AH or 65AH in a separate enclosure if site code requires longer standby.
- Form C Supervision Contacts — AC and Battery: Both AC failure and battery fault conditions break out as Form C dry contacts. Wire these directly to your alarm panel or monitoring system for real-time fault annunciation without polling the unit manually.
- Over-Voltage Protection and Filtered/Regulated Output: Regulated DC output protects sensitive readers and control boards from voltage spikes. Unregulated or unfiltered supplies are a common root cause of intermittent access control faults — this eliminates that variable.
- LED Status Indicators: Dedicated LEDs show 115VAC present, DC output active, and battery discharged or disconnected — cuts commissioning time and simplifies field troubleshooting without metering.
- Operating Range 0°C to 49°C (32°F to 120°F): Rated for the thermal envelope of most indoor equipment rooms and IDF closets. The 246 BTU/Hr. heat output is modest but should factor into enclosure ventilation planning in tight telecom rooms.
Integration and Compatibility
The MAXFIT77E fits into any access control power distribution architecture requiring supervised 24VDC. Form C contacts integrate with virtually all commercial alarm panels and central monitoring receivers. The dual-output topology suits mixed deployments — one output for locking hardware, one for readers and peripheral devices — reducing cross-fault risk. Pair with a compatible Altronix power distribution module when you need to break out additional fused outputs per door. For sites evaluating battery runtime, consult the power supply sizing guide before specifying battery count. Note: batteries are sold separately.
Frequently Asked Questions
Q: How many batteries does the MAXFIT77E enclosure hold internally?
A: The BC750 enclosure accommodates up to four 12VDC/12AH batteries internally. For higher-capacity standby (40AH or 65AH), a separate enclosure is required. Batteries are sold separately.
Q: What type of batteries does the MAXFIT77E support?
A: Sealed lead-acid or gel-type 12VDC batteries only. Do not install wet-cell or lithium batteries in this enclosure.
Q: Does the MAXFIT77E provide supervision contacts for integration with an alarm panel?
A: Yes. Both AC failure and battery fault conditions are reported via Form C dry contacts, which wire directly to any compatible alarm panel or monitoring system.
Q: What is the warranty on the MAXFIT77E?
A: Altronix covers the MAXFIT77E under their lifetime warranty per manufacturer documentation.
Q: Can the MAXFIT77E be used outdoors?
A: No. The BC750 enclosure is rated for indoor wall-mount use only. Do not install in locations subject to moisture, condensation, or temperatures outside 0°C to 49°C.
Q: What is the heat output of the MAXFIT77E and does it require ventilation?
A: The unit dissipates approximately 246 BTU/Hr. at full dual 24VDC load. Factor this into rack room or closet ventilation design, especially in sealed enclosures.
The MAXFIT77E is the unit I reach for when a project needs two isolated 24VDC circuits with battery backup and supervision in a single wall-mount footprint. The instantaneous failover on AC loss is the feature that matters most in access control — that split-second dropout is long enough to reset some door controllers, and this unit eliminates it entirely.
Technical Highlights:
- Dual Independent 10A Outputs: Each output is fully independent at 24VDC/10A. Separating lock power from reader/peripheral power means a wiring fault on one circuit cannot starve the other — that isolation is worth more than the aggregate amperage figure.
- Form C Supervision Contacts: Both AC fail and battery fault break out as dry Form C contacts. On any monitored site, these feed directly into the alarm panel — you get real-time fault annunciation without any polling logic or additional monitoring hardware.
- Four-Battery Internal Capacity: Four 12VDC/12AH batteries fit inside the BC750 enclosure. At moderate loads that runtime is substantial; for code-required standby calculations, use the 40AH/65AH external option and size accordingly before final submittal.
Deployment Considerations:
- The enclosure draws 8.8A at 115VAC — confirm your branch circuit allocation early. On multi-unit installs in a single electrical room, panel capacity gets consumed faster than integrators expect.
- At 246 BTU/Hr. heat output and 21.7 lbs. product weight (27.1 lbs. shipped), plan your wall-mount backing and closet ventilation before rough-in. In a sealed telecom room with multiple units, thermal load adds up quickly.
The MAXFIT77E is the right call for mid-size commercial access control deployments — multi-door office buildouts, healthcare corridors, or education facilities — where you need supervised dual-circuit 24VDC power, battery backup, and panel integration in a code-compliant wall-mount package.
