wiring camper shell dome light to battery

Hey everyone. i’m having some trouble with wiring my dome light provided with my camper shell to my battery. in theory I thought I had it correct, it works, but kills my battery and requires a jump start overnight. even when the light is almost always off.

This here is the dome light, both the dome light and the 3rd brake light are wired into a fuse box.

The chassis at the bottom pointed at by the blue arrow feeds 3 wires, black, solid red, and white and red.

all labeled in the photo. black is my ground, red & white is my brake light, and solid red is my dome light. I have the dome light fed underneath the taillight compartment and wired to the frame underneath my truck directly to my battery.

As I said, it works as it should, but kills my battery overnight, and sometimes will die as soon as I park it not allowing me to even lock it with my key fob. toyota gave me a new battery recently due to the factory battery giving me a ton of issues, it was replaced a month ago and has not given me any issues until connecting the dome light to it, so I doubt the battery is the issue. I know there is still a current traveling even when my truck is off, but is it enough to kill my battery? what is my issue here? is it possibly my ground? it is barely hanging onto a bolt in the tail light compartment but that idea was given to me in a youtube video. The dome light is something I would love to keep as an option because I go camping a lot and it is super convenient. electrical is clearly not my strong suit even on a simple job like this, so any help or advice is greatly appreciated!

 

Why is the ground wire barely hanging on to a ground lug in the back of your truck? That doesn’t sound safe in that the resistance caused by doing that could cause the wire to heat up. Do you have a meter that you can measure the amps across the battery and the hot wire from the light when everything is turned off to see if there is current flowing between them? Simply unscrew the light’s positive wire from the battery and put the two leads from the meter (set in amperage) across from the positive battery post to the positive light wire. It should have 0 Amps.

Your battery should not be draining over night just from the light in back when it’s turned off. I suspect that the battery is not fully charging or something else is drawing power from it.

Your ground should look like this back there:

 

Prior to having my shell installed I pulled a wire and added dedicated power to the bed. I did this for two reasons I knew I wanted to add power for my fridge. But most of all I didn’t trust the company installing the shell running the wires to the battery. I have a Switch-Pros and all kinds of things wired under the hood.

It looks like we have the same dome light for the shell and the same fuse box. I have a Leer 100xr.

When they installed my shell , I just asked them to wire it directly to my fuse block.

Here are some pics of my set up. I know it doesn’t help much now, but I can try to pull the light and trace all the wiring tomorrow, depending on when I get home from work if that helps.

This was prior to having the shell installed.

 

going to agree with this. That light should not be enough to drain the battery.
Also the OP made a comment about sometimes the battery is so drained you can’t lock the doors, you got other problems. There is no way a small light should be over working you charging system and the battery.
I would charge the battery with a charger, not the truck and disconnect the wire going to your shell light and start troubleshooting the amp draw on the battery.

 

@Puppypunter or @kmorgan3 sells a breakout harness. Could help ya out.

 

Is it possible it is the ground alone? it clearly is pulling power 24/& whether it be enough to kill it or not. but the battery is brand new and I have tested it. the day it died as soon as it parked to where I cannot lock it was minutes after jumping it. the connection has been removed from my battery since posting this and I have had no issues with the battery since. is it possible I need a relay? I watched a youtube video: ( https://www.youtube.com/watch?v=OPsz3iLbitM&t=189s ) he has the same setup as mine. all except at 3:05 he has fuse on the wire by the battery, is that something you think would fix it? I personally have never seen that so i'm not sure where I would even pick that up. any thoughts or suggestions are extremely appreciated, I lord willing would love to have this resolved before my camping trip this weekend. thank you for helping!

 

A fuse won't fix the problem but you should have one. You should also have a good solid ground. Do you have a multimeter? You need to see if it's still drawing power when the light is off and do some trouble shooting from there.

A parasitic drain test will help you to identify what's drawing the power. I just had to do go through this with my Mustang and it's not fun. Whatever is drawing enough power to kill a battery overnight will show a large pretty easy to find draw.

But if you need it this weekend maybe just get a battery (AA/AAA) powered LED dome light as a temporary solution until you can get this sorted out?

 

I would
1) make sure you have a good ground. Do you have an ohm/continuity meter to test it?
2) check the wire running to the battery, are there any connection in that line, are they good? Are there any spots where the wire could be grounded? Again if you have a ohm/continuity meter to check it against a ground.
3) After 1 & 2 are done, with the light turned off, just place the positive wire on the battery, are you getting a spark of any kind? If you are, then that light is still drawing current and I would wonder if the light itself has a problem. As for the spark check, in the garage in darker conditions helps a person see it. You can try this with the light on and off to see if there is a difference.

 

Is that the 6 circuit w/negative bus? 10awg wire from the battery? The fused wire in the picture is for the switch/volt/cig panel above? Can you show me your current setup (you said this was prior to the canopy and assuming you have it by now 6+ months later)

 

Instead of the spark test, you can also buy a volt meter from Harbor Freight for under $10 that can also tell you if the light circuit is drawing power. While many people will say this cheapo voltmeter is junk, it is good enough for what you are trying to check here and even be useful for other projects as well.

 

Fyi This is an old thread I bumped that’s related to some research I’m doing