Altronix MAXIMAL3RHD 8-Output Access Power Controller

The MAXIMAL3RHD is a workhorse power controller that we've spec'd into everything from small office parks to university campus deployments. What sets it apart from generic rack-mount 24VDC supplies is the operational intelligence built in—the supervision relays, battery monitoring, and fire alarm disconnect aren't afterthoughts bolted onto a power supply, they're core to the design. In our experience, the difference shows when a power event happens at 2 a.m. and the access panel can automatically alert the NOC that battery backup is active, or when a building operator glances at the MAXIMAL3RHD's status lights and knows immediately that the AC failed 30 minutes ago and the battery is still good. On multi-door jobs (8+ entry points), the consolidation of power distribution and backup into a single supervised rack chassis has consistently reduced both initial cabling labor and ongoing maintenance cost versus distributed individual supplies at each lock.

Technical Highlights:

• Dual-Voltage Per-Channel Selectable Output: 12VDC @ 4A or 24VDC @ 3A per channel means you can serve a mix of 12V credential readers and 24V solenoids without external DC-DC converters or dual supplies. We've used this to simplify retrofit projects where the facility had legacy 12V hardware mixed with new 24V locks.
• Independent Output Supervision: Each channel is monitored for open-circuit and short-circuit conditions. The access panel sees every lock's power status in real time—far better than a single "power OK" indicator on eight undifferentiated outputs. Early warning on a failing lock power cable means you can schedule replacement during business hours instead of a 3 a.m. emergency unlock call.
• Fire Alarm Disconnect Relay: Integrated directly into the chassis—no external contactor, no separate failsafe module, no wiring errors during install. In our experience, having the fire alarm relay housed in the MAXIMAL3RHD eliminates a major source of code-inspection findings and reduces installation time by a day on typical multi-door jobs.
• AC Fail and Low Battery Monitoring: Real-time supervision signals alert the access panel the moment mains power is lost, and again when battery voltage drops below usable threshold. We've seen this prevent silent battery degradation—you catch a bad cell before the battery is completely dead and unable to hold the locks open during an actual fire event.
• 2U Rack Mount with Standard 115VAC Input: No need for dedicated 3-phase or special electrical runs. In the average office or institutional environment, a 115VAC outlet in the IDF or electrical room is already available. Rack mounting keeps the unit out of ceiling spaces where it's hard to service, and consolidates all access power infrastructure in one visible location.

Deployment Considerations:

• Battery sizing is critical—you must size the backup battery for the cumulative load of all eight outputs in failsafe mode (typically all locks held open). The MAXIMAL3RHD provides the charging circuit and supervision, but you specify the battery separately based on run-time requirement. Consult the access control engineer on expected outage duration; 15 minutes vs. 2 hours changes battery cost significantly.
• Fire alarm wiring must be verified by the integrator and inspected by the AHJ (Authority Having Jurisdiction). The MAXIMAL3RHD's fire alarm relay is straightforward, but the wiring loop from the fire panel to the MAXIMAL3RHD to the access control panel is often a sticking point on code reviews. Document the circuit clearly and have the fire alarm contractor sign off.
• The eight output channels are independent, but they all draw from a single 115VAC input and share a single battery backup. If you're power-hungry (e.g., eight 4A @ 12VDC loads pulling 32A total), the input circuit and battery must be sized for the aggregate load, not per-channel. Oversizing is cheap insurance; undersizing is a field failure waiting to happen.
• Rack-mount placement: ensure ventilation around the unit, especially if the battery is mounted directly above or below it. Charging current and deep-cycle discharges generate heat. We've seen units fail prematurely when wedged into hot, poorly-ventilated IDFs. Leave 3-4 inches of clearance on all sides if possible.
• Access control panel compatibility is broad (Salto, Allegion, HID, Honeywell, etc.), but always verify that the panel's relay inputs support the MAXIMAL3RHD's supervision output voltage and logic (12VDC, dry contact, etc.). Modern panels are compatible, but legacy systems occasionally require an intermediate relay module.

The MAXIMAL3RHD is the right choice for any multi-door access control job where code compliance, operational visibility, and total-cost-of-ownership matter more than squeezing the lowest per-unit supply cost. For a single-door retrofit or a budget-constrained installation where code-compliant fire alarm disconnect isn't required, a simpler wall-mounted 24VDC supply might suffice. But on institutional campuses, office parks, and critical facilities where access security and life-safety redundancy are both priorities, this is the standard we recommend. Explore more Altronix power control and access solutions.