CTD wiring questions from an Electrophobic

[Cummins Dog]

Please bare with me. I'm a confirmed Electrophobic and before I attempt to wire up some LEDs to the truck I just want to go over a couple things to avoid problems. As anyone who's worked with electricity knows you don't want to screw up and let the blue smoke out as that's usually an expensive mistake. Anyway, here goes.

#1 - on the CTD we have two batteries. I know its always recommended to take the ground off the battery when working on electrical parts so my question is do I need to take the ground off both batteries or are they wired in such a way that taking the ground off one disconnects the other?

#2 - once the ground is disconnected will my uconnect and dash info setting, programed radio stations etc. be lost or does taking the ground(s) off not affect that?

#3 - How can you tell how many amps a light will draw if there's nothing that indicates that on the box, light or instructions (if there is any instructions)? In other words how do you know what size (gage) wire and what amp fuse to use?

Thanks in advance for all you electrical experts (which I am not one of).

 

[Hootbro]

1. Your two batteries are wired in parallel. You will need to disconnect both battery grounds.

2. Your memory retentions for everything will be lost once the grounds are pulled from the batteries after a few minutes disconnected.

3. You need a amp capable multimeter or clamp meter rated for DC voltage. Use Google foo for how to do that. Once amp draw is determined, use Google foo again to find appropriate gauge wire to use. Make sure it is fused when installed.

 

[Galion]

#3 - How can you tell how many amps a light will draw if there's nothing that indicates that on the box, light or instructions (if there is any instructions)? In other words how do you know what size (gage) wire and what amp fuse to use?

You can calculate the amperage draw if you know the wattage and voltage (12v in this case). Usually for led's they will advertise how many watts they are so you should be able to find that from wherever sold it. Otherwise if it's a light bar 90% of them use 3w Led's so you can count the number of led's to find out. (If those two options won't work for you, a multimeter will be required to actually test it). Once you know the watts and volts simply divide total watts over volts to find amperage. (Watts/Volts=Amps)

As for appropriate gauge size here's a basic chart from google: