Newmar 115-12-20A Heavy-Duty Power Supply 115/230VAC to 12VDC 20A

The Newmar 115-12-20A (part 115-12-20A) is the heavy-duty 12-volt DC marine power supply built for commercial-vessel communication and navigation equipment installations where reliability isn't optional. Convert 115 or 230 VAC shore power input to clean regulated 12 VDC output at 20 amps intermittent or 8 amps continuous, drive the critical electronics on the boat (VHF radios, AIS transponders, chartplotters, autopilot computers, navigation lights, and the rest of the 12V load), and survive the marine environment through years of vibration, salt air, temperature swings, and the rough handling that commercial vessels routinely subject equipment to.

Heavy Duty Series construction. Newmar's Heavy Duty Series is the company's commercial-grade marine power supply line. Built specifically for the application where the boat depends on the power supply working: the captain's VHF needs to call out, the autopilot computer needs the boat to stay on heading, the chartplotter needs to display where the boat is. A power supply failure in those scenarios isn't a minor inconvenience - it's potentially a safety issue. The Heavy Duty Series construction (conformal-coated PC board, heavy-duty aluminum case with shock mounts, oversized heat sinks for derated thermal operation, heavy-duty over-protection circuitry) is engineered for the long service life and high reliability that those scenarios demand.

115 OR 230 VAC input, slide-switch selectable. The front panel has a slide switch to select between 115 VAC and 230 VAC input voltage. Same unit, same internals, just flip the switch at install to match the boat's shore-power voltage. For boats wired with 115 VAC shore power (most U.S. boats under 35 feet), select 115. For boats with 230 VAC shore power (most boats over 35 feet, European boats, commercial vessels), select 230. Input range tolerance: 105-125 VAC (when set to 115) or 210-250 VAC (when set to 230). Below those ranges (down to 110 VAC / 220 VAC), the supply derates to 50 percent output capacity rather than failing - useful for boats sitting at marina pedestals with weak shore power.

20 amps intermittent / 8 amps continuous output. Two output ratings cover two use cases. The 20-amp intermittent rating handles peak loads from equipment like radar transmitters, autopilot rudder corrections, and other intermittent high-current draws (intermittent = up to 20 minutes on time at 20% duty cycle). The 8-amp continuous rating is what the supply delivers indefinitely (24 hours per day at 100% duty cycle). For typical marine electronics installs the actual sustained load is well under 8 amps, with intermittent peaks well under 20 amps - the supply has plenty of headroom for typical loads.

Excellent regulation: 1 percent line and load. Output voltage stays within 1 percent of the setpoint regardless of input voltage variation (within the 105-125 / 210-250 VAC range) and regardless of load (from no-load to full rated output). 1 percent regulation is meaningfully tighter than budget power supplies (which often spec 5-10 percent) and matters for sensitive electronics that don't like input voltage variation. Marine VHF radios, GPS receivers, and other RF equipment in particular benefit from clean stable supply voltage.

Low ripple: under 40 mV peak-to-peak. Ripple is the residual AC waveform riding on the DC output after the rectifier and filter capacitors. Lower ripple means cleaner DC, which means less radio-frequency interference picked up by sensitive electronics powered by the supply. Newmar's 40 mV P-P spec is comparable to the cleanest commercial power supplies and well within the noise tolerance of typical marine electronics.

Polyurethane conformal-coated PC board. Conformal coating is a thin insulating polyurethane layer applied to the assembled PC board to protect against moisture, salt air, and conductive contaminants in the marine environment. Without conformal coating, salt-laden moisture eventually shorts adjacent traces or grows green corrosion that destroys the PC board. With conformal coating, the board survives years of marine humidity exposure without electrical degradation. The coating is one of the differences between commercial-grade and consumer-grade marine electronics.

Heavy-duty aluminum case with integral shock mounts. The case is heavy-gauge aluminum (corrosion-resistant in marine service, good thermal conductor for heat dissipation) with shock-mount features integrated into the case design. The shock mounts isolate the internal electronics from boat-borne mechanical vibration that would otherwise stress solder joints and wear out connectors over time. Mount the supply directly to the boat's electrical panel via the integral mount points - no separate vibration isolation hardware needed.

Large heat sink fins for cool operation. The semiconductor power devices inside the supply (rectifier diodes, regulator pass transistors) generate significant heat at full load. Newmar uses oversized heat sink fins on the case exterior to extract that heat efficiently and dissipate it to the surrounding air. Cool operation = long component life. The supply runs continuously at rated load without thermal stress.

Comprehensive protection. The supply includes overvoltage protection (shuts down if output voltage exceeds safe levels), current limit (protects the supply at 105 percent of intermittent rating - prevents damage from output short circuits), thermal overload (shuts down at 85 C case temperature to prevent component damage), and both input-side and output-side fusing. Combined, the protection covers all the realistic failure modes that marine power supplies see in service.

Internally adjustable output: 12.6-14.5 VDC. The default output is 13.6 VDC (the standard nominal voltage for 12V boat electrical systems running on engine-charged batteries). For applications where the powered equipment needs a different specific voltage, an internal trim pot lets the installer adjust the output anywhere from 12.6 to 14.5 VDC. Useful for floating connected batteries (set to 13.2-13.5 VDC for AGM or flooded float charging) or for matching specific equipment voltage tolerance windows.

Operating environment. 0 to 50 C operating temperature range. Derates linearly from 100 percent capacity at 40 C to 50 percent at 50 C. Thermal shutdown at 85 C case temperature (the safety backstop). For typical engine compartment installs where ambient can hit 50 C in summer, the derating means the supply still operates without damage, just at reduced output capacity.

Specs at a glance. Input: 115 or 230 VAC selectable, 50-60 Hz. Output: 13.6 VDC nominal (12.6-14.5 VDC adjustable). Output current: 20 A intermittent / 8 A continuous. Regulation: 1 percent line and load. Ripple: under 40 mV P-P. Dimensions: 5.7 H x 4.8 W x 16.3 D inches. Weight: 20 lb. Conformal-coated PC board, aluminum case with shock mounts, comprehensive protection.

What's in the box. The Newmar 115-12-20A power supply (with all internal protection and adjustment features pre-set to factory defaults), and the standard install / operations documentation. Required separately: AC supply wiring with appropriate fuse, DC output wiring sized for the actual load current.

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