Newmar 32-12-25 DC-DC Converter 20-50VDC to 13.6VDC 25A

The Newmar 32-12-25 (part number 32-12-25) is the heavy-duty marine and mobile DC-DC converter that takes a 24V (nominal 20-50 VDC) input and delivers a tightly regulated 13.6 volt output at up to 25 amps intermittent and 20 amps continuous. Built by Newmar, the company that's been making marine and military DC power conversion gear for decades, this converter is what you specify when the load is mission-critical and when you can't afford to come back to the dock to replace a failed converter.

What it actually does on a boat. Most modern offshore boats and a lot of commercial fishing and tug applications run a 24V house bus for inverter loads and bow thrusters and big DC accessories, but the navigation electronics, the VHF radios, the bilge pumps, the cabin lighting, and the instrument backbone are still 12V. You can't just feed those 12V loads from the 24V bus directly. You need a DC-DC converter that takes 24V in and gives you regulated 12V out. That's exactly what this unit does, with the build quality to keep doing it for decades.

The 20-50 VDC input range is wider than what you'll see on consumer-grade converters, and that matters for two reasons. First, 24V house systems can sag well below nominal under heavy load (a sagging bank under a 100A inverter draw can drop to 22V or less), and the converter needs to keep delivering regulated output through that sag. Second, if you ever have a battery balancer issue or a cell failure that elevates bus voltage temporarily, the converter doesn't fault out. It just keeps working through the disturbance.

13.6 VDC output is the right voltage for 12V house electronics. It's the float-charge voltage for a typical 12V battery and matches the resting voltage of healthy 12V flooded or AGM batteries with the alternator on. Most marine 12V electronics are designed for this exact voltage range. The output is internally adjustable from 12.6 to 14.5 volts, so if you need to tune for a specific load (like maintaining a 12V backup battery at a different float setpoint), you can.

25 amps intermittent and 20 amps continuous is the right rating for a typical mid-size offshore navigation suite. A complete suite of two MFDs, a chartplotter, an autopilot, a VHF, an AIS, a radar interface, instruments, and the cabin lighting will pull about 12 to 18 amps with everything running. The 20-amp continuous rating handles that with margin. The 25-amp intermittent rating handles the brief surges when the radar transmitter pulses or the autopilot drive engages.

The build quality is what separates this from the consumer DC-DC converters that fail after a couple of seasons of marine use. Polyurethane conformal coating on the PC boards seals the electronics against salt fog, condensation, and humidity. The case is corrosion-resistant anodized aluminum, not stamped steel or painted mild steel that flash-rusts in a year. Heavy-duty shock mounts on the chassis isolate the internal components from hull-pounding vibration that destroys lesser converters in offshore use. Heat is dissipated through large heat sink fins on the case, with no cooling fan to fail.

Protection circuits cover the failure modes that matter. Current limiting protects the converter and the load from overcurrent faults. Automatic thermal shutdown protects against overtemperature events (the unit shuts itself down before damage and recovers when it cools). Short-circuit protection means a downstream fault won't blow the converter. Reverse polarity protection means an install error won't kill it. Overvoltage protection on the output protects connected electronics from a fault inside the converter. CE marked.

The performance numbers tell the engineering story. Output regulation is 1% line and load. Ripple is 150 mV peak-to-peak maximum, which is well under what most 12V electronics specify as their input ripple tolerance. Switching frequency is 40 kHz, which is low enough to avoid radio-frequency interference issues with VHF and HF marine radios. Efficiency is 85% typical, which means about 15% of the input power becomes heat that the case dissipates. Idle current is under 100 mA including the power-on indicator. Input/output isolation to chassis is rated 250 VDC.

Duty cycle ratings. Intermittent rating: 20 minutes maximum on-time at 25A with 20% duty (current limit set at about 105% of intermittent rating). Continuous rating: 24 hours at 100% duty at 20A. For practical use, run the converter at 20A continuous indefinitely, and tap the extra 5A intermittent margin for short surges.

This is a negative-ground converter for negative-ground vessels (the standard for almost all modern marine installations). For positive-ground installations (some older or specialized commercial vessels), Newmar makes the Isolated Series with a different topology. Pick the right ground polarity for your install before ordering.

Operating temperature range: 0 to 50 degrees Celsius (32 to 122 Fahrenheit) at full rating, with linear derate above 50 degrees C. For most marine engine room installs that's plenty of margin. For installs in extremely hot equipment compartments, consult the spec sheet for derate curves.

Newmar warranty terms. Service runs through the Newmar dealer network in the U.S.

Same-day shipping before 3 PM ET on in-stock units.