Go with the flow

Hi Kevin,Non-duplex battery cables are fine for most boat wiring projects

I recently added a new set of battery cables to the boat wiring on my Smokercraft fishing boat.

My question is:

Are marine electrical cables directional? That is, do they allow current to flow either way – or do you have to orient them correctly so the juice goes where you need it?

Thank you for your help.



Excellent question.

As you probably remember from high school, DC stands for Directional Current. This means that unless you sprung for a set of expensive full-duplex cables, your new wiring will only let the current flow one way.

Most better quality non-duplex battery cables will have printed arrows to show the current direction. If these are absent, simply remember that the electricity will always follow the printing on the outside of the cable. Or as the old-timers put it, “if it reads from left to right, your battery will get charged tonight”.

The only exception is if your battery is higher than your engine alternator. Since electricity naturally flows downhill, a severe height differential – coupled with non-duplex cable – can cause it to stop moving altogether.

I hope that this is helpful…and that you enjoy this special day.