Constant 12V for Cap Lights?

Where are you guys pulling your constant 12V power source from to run interior LED cap lights? I could run all the way up to the battery, but it seems like a long way for a simple task.

 

As far as i know, the trailer light connector is not hot all the time, so running up front is about your only option. That's what i did for my strip lights.

For the small LED light that came with teh cap, i ran it to the cargo light switch in the cab, so it comes on/off with the doors but can be manually turned on from the cab as well (and will automatically turn off so it doesn't drain the battery).

 

You might want to consider a separate battery altogether.

 

Mine runs to the battery with inline fuse

 

Interesting suggestion. I could drop a small lithium ion or agm battery like I use for my ice fishing graph in one of the ammo boxes that are built into my Decked drawers. From there I should be able to tie into the trailer wiring and theoretically it will charge whenever the truck is running. The biggest benefit here is I never have to worry about draining the main battery leaving the lights on.

 

Check the #4 pin

 

I went straight to the battery. I wanted constant hot in the bed without having to futz with going to the cab to open door, turn on switch. key, nuthin...

I want to be able to turn on my strip lights, or plug in my portable shower and rinse after surfing, whatever... just open tailgate and BAM.

 

If you do go directly to the battery, be certain to put a fuse or circuit breaker really close to the battery. Last thing you want is a hot 12v 500+ amps non fused wire anywhere where it could become grounded. That could potentially be a fire starter. Not good!
Edit: same for secondary battery, short circuit protection!

 

Which brings up a good question;

I'm 61 years old (and kinda' hate anything beyond very basic electrical) I don't remember ever doing anything more than a fuse.

Fused hot, ground, switch, etc., fine. What determines when you need to start using relays, buss bars, etc.?

 

A relay is used between the power source and the item that is being powered. The switch powers the relay which is actually closing the circuit. Most automotive switches aren't designed to carry very much amperage and if used to close the circuit to power the item they can easily become hot and cause a fire. So to answer your question, when the amperage draw is getting up around 75% of the switch current rating it's time to use a relay rated for about 130% or more of the current that will flow between the power source and the item that will be powered. Sorry for the very brief explanation, quite busy ATM. Be safe and BTW, happy to see your recovery!

 

Thanks very much, I appreciate that. Especially that last part!

So as a gross oversimplification, the fuse is still there to protect the entire circuit, while the relay is more to protect the switch?

 

Yeah

 

Hey, look at that!