12V Wiring Help

  • HTML tutorial

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
I need a resistor, relay, or diode that will only let 12V power travel one direction.
A diode is probably your easiest solution if you don't mind the voltage drop inherent with them.

Please tell us more about the application to help with the determination.
 
  • Like
Reactions: M Rose

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
Looking to put several lights on one switch in one location (in Jeep) but still be able to switch individual at another on trailer.
See if this video helps you any:



I monkey around with diodes quite a bit so don't hesitate to let me know if I can help further. One main consideration is to be sure to use diodes with enough current capacity. Also, some diodes will reduce the voltage more than others. Schottky diodes may be a good choice because their voltage drop is often less than a standard diode.
 
  • Like
Reactions: M Rose

Jason Shelby

Rank VII
Member
Investor

Creator III

5,660
Lexington, Henderson County, Tennessee, United States
First Name
Jason
Last Name
Shelby
Member #

6080

Service Branch
TN National Guard
Looking to put several lights on one switch in one location (in Jeep) but still be able to switch individual at another on trailer.
See if this video helps you any:



I monkey around with diodes quite a bit so don't hesitate to let me know if I can help further. One main consideration is to be sure to use diodes with enough current capacity. Also, some diodes will reduce the voltage more than others. Schottky diodes may be a good choice because their voltage drop is often less than a standard diode.
Thanks, little deeper explanation of my situation. I have three sets of KC C-Series lights on my DIY camp trailer. I want to run them separately at the Trailer control panel, but run them together on one switch in the tent, so encase something happens during the night I can “light up camp”.
 
  • Like
Reactions: Neal A. Tew

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
Got it. I like the way you think!

Give me a bit to figure out the best way to get you a wiring diagram. But for now, is it safe to assume that the trailer lights are operated via relays and not straight from a switch? Also, are you going to run a wire into the tent or will you have a wireless remote?
 

Jason Shelby

Rank VII
Member
Investor

Creator III

5,660
Lexington, Henderson County, Tennessee, United States
First Name
Jason
Last Name
Shelby
Member #

6080

Service Branch
TN National Guard
Got it. I like the way you think!

Give me a bit to figure out the best way to get you a wiring diagram. But for now, is it safe to assume that the trailer lights are operated via relays and not straight from a switch? Also, are you going to run a wire into the tent or will you have a wireless remote?
The lights are currently just fused and switched, no relays, and I’ll be running a wire.
 
  • Like
Reactions: Neal A. Tew

M Rose

Local Expert
Mod Team
Member

Advocate III

5,584
Northeast Oregon, United States
First Name
Michael
Last Name
Rose
Member #

20990

Ham/GMRS Callsign
W7FSB
Service Branch
US ARMY Retired
You need one relay per switched circuit. The switch in the tent will control a relay that will control the rest of the relays bypassing the the other switches.
 

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
The lights are currently just fused and switched, no relays, and I’ll be running a wire.
Do you know what amp rating the lights are? It's easy to exceed the rating of the switch with a few lights. What model are the lights?

I crudely put this together before I saw your answer and I assumed you'd be using relays. See if you can follow it. I'll work on making another without relays.

In this diagram if two lines cross, but there is no dot at the intersection, there is no connection.

Again, I drew this with the assumption you presently had one relay per circuit:

1610128249216.png
 
  • Like
Reactions: M Rose

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
You need one relay per switched circuit. The switch in the tent will control a relay that will control the rest of the relays bypassing the the other switches.
Don't forget that he still needs the 3 trailer switches to work independently. If I understand you, you'll be tying those three together when you gang them together for the other switch. Right?
 

M Rose

Local Expert
Mod Team
Member

Advocate III

5,584
Northeast Oregon, United States
First Name
Michael
Last Name
Rose
Member #

20990

Ham/GMRS Callsign
W7FSB
Service Branch
US ARMY Retired
Do you know what amp rating the lights are? It's easy to exceed the rating of the switch with a few lights. What model are the lights?

I crudely put this together before I saw your answer and I assumed you'd be using relays. See if you can follow it. I'll work on making another without relays.

In this diagram if two lines cross, but there is no dot at the intersection, there is no connection.

Again, I drew this with the assumption you presently had one relay per circuit:

View attachment 182764
The only thing I do t like about diodes... if they fail in the trail, then no where to get new ones very easily... relays are sold almost every where.
 

M Rose

Local Expert
Mod Team
Member

Advocate III

5,584
Northeast Oregon, United States
First Name
Michael
Last Name
Rose
Member #

20990

Ham/GMRS Callsign
W7FSB
Service Branch
US ARMY Retired
Don't forget that he still needs the 3 trailer switches to work independently. If I understand you, you'll be tying those three together when you gang them together for the other switch. Right?
Yes... gang the three with one, so a total of 4 relays.
 

Neal A. Tew

US Rocky Mountain Local Expert
Mod Team
Member
Member

Member III

3,817
Pueblo West, CO
First Name
Neal
Last Name
Tew
Member #

12384

Ham/GMRS Callsign
N1TEW
I have the circuit drawn eliminating the relays, but decided against posting it because I strongly discourage against it.

You might get away with running those 3 sets of lights on 3 different switches without relays. But when you try to do that with a single switch combining all 3 you're very likely going to smoke your switch. You also don't want all that current going to the tent and back. You'd need to use a really big wire.
 

Pathfinder I

1,212
Canada
First Name
Craig
Last Name
PereferNotToSay
I can't help you on the 12V stuff, and I am not nearly as qualified to make suggestions compared to what's already been posted, but for your application there may be another way using a product like these:


They can be controlled via smartphone/bluetooth, so you can switch them individually from anywhere. The ARB Lynx system might also do this job for you with your KC Lights, but I've not looked into it much. I don't know if any of these allow you to group lights together to "light up camp" (great idea, btw), but I have app-controlled lights in my house and can do groups, individual lamps, etc. with a lot of customization so this might give you an alternative path to look at to achieve your outcome.

Granted, while it's potentially simpler to set up, it's VERY reliant on tech so I wouldn't suggest this is a "better" solution as depending on your needs, a wired connection may provide you with a lot more robustness, dependability, and repairability which might be critical for your use. So again -- not a "better" solution, just a different road on the map to a similar destination that I thought you might want to explore. I only found out about these a few weeks back myself.
 
  • Like
Reactions: Neal A. Tew

slomatt

Rank V

Influencer I

1,723
Bay Area, CA
One potential addition to Neal's diagram would be to use a single pole double throw (SPDT) switch with a center off position for the tent switch, with +12v wired to the center pin, the diodes+relays attached to one throw, and the +12v for the 3 trailer switches attached to the other throw.

This way when the tent switch is in the "up" position all the lights would go on. When it is in the "down" position the 3 trailer switches would control the lights. And in the center position the lights would be off regardless of the position of the trailer switches.