Saturday, November 20, 2021

Rewiring our LED lighting circuit

Protecting our LED Lighting Circuit

I recently completed the BoatHowTo 'Boat Electrics 101 - Safe & Reliable DC Systems' online Course and it was worth the time and effort, it will help me when I get into our rewiring job on Eximius.  With what I leaned from the course,  I recently upgraded our Auto Pilot which involved removing all of the old wiring and rewiring the Cockpit Instrument power supplies. That was due to the obvious bad wiring install that was done before we took on the boat.

As part of the Boat Electrics 101, a 'bonus' lesson was about LED lighting, it went way past what I needed to know, but, again, was worth the effort. I have a better understanding of the types of LED lighting and the various options as far as appropriate LED's for particular use. eg. Light temperatures suitable for use inside a cabin etc.

That last lesson also explained an issue with Cheap LED lighting strips, I use quite a few of those: Galley, Head, Cabin and in equipment lockers. The issue is that those low cost LEDs have no power management on the strips and so they receive whatever voltage is available at their connection. When the Batteries are charging, the voltage could be as high as 14v DC when they are designed to operate at 12v DC. This high voltage will reduce their life expectancy.

My initial thought was to install a voltage reducer with a constant 12v DC output between the Lighting Circuit Breaker and the lighting Circuit. But then I thought, what about the Navigation Lights( Bow Lights and Stern Light), Anchor Light, Deck and Steaming light? All of those are now LEDs and potentially suffer from the same issue - over voltage reducing their life expectancy.

That complicates things slightly, I'll have to check the current draw when all of the lights are on, including the Nav lights. If the current draw with all the lamps on is less than 6A, then I can simply create a sub-circuit supply to those circuit breakers which is protected by the Voltage Reducer. Worst case scenario is that I would need to add two of the reducers, one for the Interior lighting circuits and another for the exterior lighting circuits.

This 8V-40V to 12V 6A 72W Voltage Reducer converts whatever the input voltage is (between 8v and 40v DC) to a reliable 12v.

6A is more current than all of our interior LED lighting combined. I'll test it onboard before installing it just to make sure there's no radio interference.

At that time I'll turn all of the lights on the boat, interior and exterior to determine the total current flow ( our electrical management system shows the current flow both In and Out of the Battery) I'll turn off the Solar Charger to ensure we're getting a true reading of the current flow.

If I'm going to go to the trouble of protecting the LED lamps/strips, I might as well rewire them all so that if one shorts out it doesn't flip the breaker and turn off all of the Interior lighting. So the plan is to break the Interior lighting into separate circuits.

Here's my initial diagram for the Interior LED lighting with the Voltage. 
Note. Because some of the circuits, eg. V-Berth, have multiple LED lamps, the Blade fuses will be sized accordingly.
The Exterior lights have their dedicated Circuit Breaker, I'll have to figure those out later, I'm sure they jointly take more than 6amps which is the limit of this particular Voltage Converter. I don't have an issue installing multiple converters, but they do cost $27 on Amazon. I'll update the diagram when I figure out the current in each circuit.

See you on the water - and after another grotty weekend here in South Florida cancelled a long weekend cruise, it had better be soon!

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