Dual power source...

[galladanb]

I'm fairly certain this has not been asked about before, but?

Can I wire my overhead lights with two power sources?
I want the overhead lights to come on when the door opens just like factory default.

AND...

I want the overhead lights to come on when I use the "house" dimmer when we are in the back.

FYI, the factory config has the cockpit light, a switchable light by the side cargo doors,
And a third light back by the rear doors. All of these come on whenever any door is opened.
And that's ok, I want to retain that feature, as it can be controlled at the drivers position.
In addition, if we are doing our stealth thing, I want full lights if someone tries to enter while we are sleeping. I want to retain the factory default power system from the starter battery.

I also want to be able to either have full OR DIMMED lights when we want them from the back. I anticipate this new features power source will come from our new battery system, and not the trucks.

I plan on keeping the cockpit light as is, and changing the two cargo area lights out for cute little led pucks... ( By the way, has anybody got a link on an led replacement for the cockpit light bulb???)

So here is the questions...
Is this doable? 
Any problems expected?
Is it ok for a light fixture to have multiple independent power sources?
Am I freakin nurtz? 

Such Fun!

 

[StarEcho]

This is an interesting question! It makes me think of a transfer switch in an RV. Something that switches from multiple power sources to run electrical switches. In a transfer switch you have to determine which takes preference and if that is running and the other cuts in, it is ignored as a power source.

If you had your lights on by the house battery you wouldn't want the starter battery to add juice to the mix when a door is opened, right? Or is that even a worry? I don't know, that's why I think it's an interesting question and I'll be looking to see how the experts advise.

 

[mayble]

I went round with this issue myself.  The cargo lights in my van will stay on forever as long as the door is open.  Not so convenient for camping, when the door will be open most of the time.
I decided to replace one of the original cargo area lights with a switchable led light, so it will come on when a door is opened (as long as the switch is on) but I can switch it off when I want to.
I yanked out all the other cargo area lights and will be installing led lights run off the house battery.
It was the simplest solution I could come up with.

 

[Optimistic Paranoid]

I've been thinking about this since you first posted, and I really see no reason why it couldn't work.

Even if somebody opened the doors while you had the back switch on, it wouldn't double the current or voltage or anything like that, the bulbs would just have two paths to draw their ordinary amount of power from.

As far as LED replacements, you need to find the bulb numbers either from the bulbs themselves, or from the owner's manual.  Once you have the numbers,

https://www.superbrightleds.com/


Should be able to provide bulbs for you, Whether or not LED's can be dimmed, I have no idea.

As for your last question, this is not an either/or situation.  Just because it will work, that doesn't prove you're not nurtz.

 

[Almost There]

LED's CAN be dimmed. I have a commercially made LED strip light over the kitchen counter that has a dimmer switch on it. It's great for in the evenings when I don't need the bright glare of the full LED light that is needed for kitchen work.

I have no idea how or where to deal with a separate dimmer switch so I'm leaving that to the people who do.

 

[Trebor English]

Rather than make one set of lamps work from two sources yet keep the sources isolated you could just add new lights keeping the old function unbroken.

 

[tx2sturgis]

The answer is yes, or maybe, no.

Yes it can be done. Nothing is impossible, it just depends on how determined you are.

How handy are you at tracing circuits, figuring out schematics, installing relays and maybe diodes, and improvising?

Another fly in the ointment is this:

On many newer vehicles the lights are controlled by the main computer or a dashboard computer or power module.

You will know if yours is because the lights will be on a timed delay when you shut the doors, they may come on when you hit the keyfob 'unlock' button, and they may or may not slowly fade when they do turn off. This behavior of the interior lights means that they are under computer control.

An older vehicle wont do any of that stuff, unless maybe its a Cadillac or Lexus or something like that.

It would be far easier and faster to install separate light fixtures, that is what most of us do, and leave the factory wiring un-molested.

 

[galladanb]

Cool answers! THANK YOU ALL!

FYI, I have the dimmer all figured out, and I made sure the LEDs I bought were dim able.

And I want to replace the factory fixtures with my newer versions, and simply use the existing wiring! Then add my new wires from the new system.

I will update y'all in a few days as to what I end up with!

Such Fun!