Battery connections for light bar

[randomXY]

Hey all - what is the right way to connect the pos & neg leads to the battery for an aux light? Right now I'm wired straight to the battery.

I added a Diode Dynamics 18" light bar below the grill of my truck and wired the power directly to the battery terminals. But there is a lot going on from the factory around that positive terminal and the owners manual states not to connect the neg directly to the battery to avoid messing with the BMS. I couldn't find any info in the manual about all those connections under the red dust cap on the positive side. [My previous vehicle was a 99 Jeep Cherokee which lacked any 'sophisticated' postive terminal setup.]

I don't plan to add any other electrical accessories so I don't need wireless switch relays or anything like that (though I will never run another wire through the firewall grommet - that was awful). Bonus points if there is an easy connection that times out with the lights or only works with the key on.

Thanks!

Sponsored

 

[Trigganometry]

If you’re powering a light bar you should use a fuse tap and pull your positive from that. You should use a relay in your setup. So load side, lights and signal side is your switch.

 

[Colo_Ranger]

Never use the battery terminal after the 225 amp fuse. If you blow that, you lose all electronics. Ask @AndyMedic how he knows...

Run one of the other posts on the positive side of the battery and install a fuse close to there.

 

[AndyMedic]

Never use the battery terminal after the 225 amp fuse. If you blow that, you lose all electronics. Ask @AndyMedic how he knows...

Run one of the other posts on the positive side of the battery and install a fuse close to there.

he’s not wrong. It’s not fun. 1 star would not recommend. Definitely use a different post.

 

[Frenchy]

Thanks to the BMS you want to have the ground on the Chassis. Not directly on the negative post of the battery. As for the power a relay setup is always great with a fuse. It may be possible that the power feeding the light(through the relay) can be connected on the positive battery connector, but not after the 225 amp fuse. You will want it on the post behind it(up in the picture). As for the control side of the relay still use a chassis ground and use a fuse tap. A fuse tap makes the job reversible.

 

[randomXY]

Thanks for the input - wiring is definitely not my wheelhouse. I used the wiring harness that came with the Diode Dynamics light bar which does have a relay and 30 amp fuse.

Good to know about the 225 amp fuse - I had no idea. Realized I circled the wrong Pos connection post in the image, corrected to show where I've actually got it connected which I believe is before the fuse (corrected image attached).

Not familiar with fuse taps. Examples I found online show connections to fuses lower than 30 in the cab (not the second fuse block in the engine bay). The wiring harness had a pre-wired switch which I already dismantled the dash to install

 

[Frenchy]

Again with the ground you do not want to go directly to the negative post. Go to the chassis for ground only. If you do not it can mess with the computers in the vehicle

 

[randomXY]

Thanks again for the help. This is what I've ended up with for battery connections. Positive connection before the 255 amp fuse and negative behind the BMS module. This is a far as I could separate the leads without needing to splice in additional wire. The harness came with a relay and 30 amp fuse already.

For anyone interested, this is their Stage Series LED 18" Lightbar Kit. I also swapped the factory fog lamps for their yellow plug & play Elite Series Fog Lamps. Both items were Christmas gifts from my wife last year (after I chose, ordered and gave them to her to wrap).

 

[Colo_Ranger]

That should work just fine. Looking forward to a night picture with that bar.

Sponsored