Why RFI Filtering Matters
A converter's basic job is simple: take 24 volts and step it down to 12 volts for equipment that wasn't built to run on the higher voltage. The problem with cheap, unfiltered converters isn't the voltage conversion itself, it's the electrical noise they generate while doing it.
Radio Frequency Interference, or RFI, shows up as static on a radio, a fish finder or GPS blanking out, or general electrical noise bleeding into anything sensitive nearby. In a truck or bus running two-way radios and navigation equipment, an unfiltered converter can quietly undermine the exact systems you're relying on. A properly RFI-filtered converter, built to New Zealand's Class B electromagnetic compatibility standard, avoids this entirely.
Sizing the Right Converter
Add up the wattage of everything the converter needs to power, then check the converter's continuous current rating against that total, not just its peak rating. Peak ratings look impressive on a spec sheet, but the continuous rating tells you what the converter can actually sustain over time.
Startup surges matter too. Some equipment, particularly anything with a compressor or motor, can draw 2 to 3 times its normal running current for a moment at switch-on. Undersizing a converter to save a few dollars is the single most common reason a perfectly good installation fails within months.
Real Options We Stock
The SDC range covers most light commercial and truck applications, from a single radio and GPS unit on the SDC-8 up to a fuller accessory load on the SDC-20. All three carry genuine RFI filtering, so you're not gambling on whether the unit will interfere with your other equipment once it's installed.
Installation Basics
Mounting Location
Heat, vibration, and moisture are the three things that shorten a converter's working life. Avoid mounting directly in an engine bay where possible, use solid brackets rather than zip ties, and pick a spot with reasonable airflow rather than a sealed, enclosed space.
Wiring and Grounding
Use wire sized correctly for the converter's rated current and cable run length, since undersized wire causes voltage drop and heat. Ground to a clean, unpainted metal surface with a dedicated ground wire rather than relying on the vehicle chassis alone.
Testing Before You Rely On It
A voltage check with no load connected only tells you half the story. Test under actual load with your equipment running, and check for RFI by holding a simple AM radio near the installation while your 12-volt gear is operating. Audible static or interference means the filtering or grounding needs attention before you put the vehicle to work.
