We can appreciate the confusion and complexities when it comes to different power sources and voltages on NMEA 2000 systems.
The standard dictates that an NMEA 2000 network will operate on 9-16VDC, so every certified product is built to this specification as a minimum. There was a point where the NMEA considered expanding the supported power supply range up to 9-24 or even 9-32VDC, however, there are some potential issues that can come with this such as Common Mode Voltage (CMV) differences going way out of tolerance, so the idea wasn’t implemented.
You may notice that some manufacturers support over 16VDC, such as Actisense products, but you should always stick to the spec where possible. The reason we don’t stray away from this when building networks is that we don’t know that every device is certified and capable of going over 9-16VDC, especially the cables and connectors being used. Cheaper NMEA 2000 lite cables will only take 3A max as per the spec, and anything over that will cause excessive heat and damage. Higher-grade cabling like Actisense and Maretron will handle higher power draws, but this is just the product being designed above the spec, rather than a dedicated requirement.
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