Salt Air Corrodes Electronics, and IP43 Has No Defence Against It

At 18 months in a marina environment, salt air reaches the PCB of every IP43-rated controller. Here's what that looks like, and why it's not a defect.

Salt air isn't spray. It's the background, an aerosol of sub-micron salt particles that exists permanently in any harbour, marina, or coastal environment. You can't see it and you can't feel it, but at 18 months, it is on every unprotected surface inside a vented electronics enclosure: on the PCB, on the connector pins, on the solder joints.

How Salt Air Corrodes a PCB

The corrosion mechanism is straightforward: salt is hygroscopic, it absorbs moisture. Once salt deposits build up on a PCB, they pull moisture from the air onto the surface even when there's no visible condensation. That moisture, combined with salt and trace metals in solder and copper traces, creates a galvanic cell. Slow, consistent, invisible, until it isn't.

Research published in IEEE Transactions on Device and Materials Reliability (Verdingovas et al., 2014) documents this failure mode: NaCl contamination combined with humidity causes electrochemical failure of PCB assemblies at concentrations that are well within what any coastal environment produces. This is not a laboratory edge case.

Kim et al. (2023) measured corrosion lifetime of printed circuit boards in marine atmosphere environments. The paper confirms the 12–24 month failure window for exposed copper and solder in a marine-class (ISO 9223 C5-M) atmosphere, which is the corrosivity class for any harbour or marina environment.

Why IP43 Doesn't Help

IP43 means a maximum of 1mm wire can enter from any angle. It does not exclude aerosol. It does not exclude vapour. The Victron SmartSolar's IP43/IP22 rating is designed for the assumption that the controller is mounted in a protected indoor space. In that space, it will last. In a marina environment, even inside a deck box with cable glands, the salt air is already there.

The second digit of the IP rating (liquid protection) grades 0 through 9K. The test method for each digit defines what "protection" means:

Salt aerosol is not tested by any of these methods. It is a different failure mode entirely, sub-micron particles carried by air, not liquid water hitting a surface. IP43's liquid protection (digit 3: spray at 60°) does not address it at all.

The Documented Failure

Users in Victron Community and DIY Solar forums describe controllers failing in coastal installations and calling the outcome a product failure. It isn't. The IP rating is doing exactly what it says: protecting against water sprayed at up to 60° from vertical. The salt aerosol enters through the normal venting, deposits on the PCB, and the corrosion proceeds.

This is a specification mismatch, the controller is IP43 installed in a C5-M corrosion environment, not a manufacturing defect. The consequence is the same for the installer: a callback. But understanding the cause is what determines the fix.

The Fix: Seal the Enclosure

IP67 is the correct rating for any electronics in a salt air environment. 30-minute submersion to 1 metre. Fully sealed: no vents, no fans, no openings of any kind. Salt aerosol cannot enter because there is no path for it to enter.

This is why the MicroCore Marine Solar Charger is fanless. A fan housing requires a vent, which is an ingress path. Passive cooling via aluminium heatsink is the only architecture compatible with a genuine IP67 rating. The entire enclosure seals. The M12 connectors seal to the same rating as the enclosure. There is no weak point.

ASTM B117 salt fog testing (500h corresponds to approximately 5–7 years of marine exposure) will be part of the validation process for this product. Not because it is required for NZ/ANZ market entry, but because it is the evidence that actually answers the question: does this survive where the Victron doesn't?