Control Flow of Current when using Multiple Power Sources

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  #1  
Old 01-18-11, 01:15 PM
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Control Flow of Current when using Multiple Power Sources

I'm trying to wire my car's headlights to come on with the unlock feature. I know this isn't the Auto section but this is much more related to the electrical section.

Basically all I'm wondering is how to prevent power from going from my new power source from going back up the stock wires. I have made a diagram to show how everything will be wired.

http://img213.imageshack.us/img213/3...krev3switc.jpg
Everything highlighted in green is the new wiring I will be doing, not highlighted is stock. The red box is where I am worried the power will go back up the lines. The black arrows (diode symbol; I was guessing that's what I need but know almost nothing about) are the only direction the current can flow.

Thanks ahead of time, I hope I can find my solution.
 
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Old 01-18-11, 01:38 PM
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A diode is an electrical check valve if you're more familiar with that terminology. In a DC circuit, current can only flow one direction through a diode.
 
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Old 01-18-11, 06:38 PM
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I'm still puzzled as to what I need to put where I marked the diodes. Is that correctly where they should be? What size/type do I need?
 
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Old 01-18-11, 09:47 PM
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One wire will power or trigger the headlights from the device. That's the wire into which you want to insert the diode. The current rating of the diode (in amps) depends upon how much current is passing through the wire.
 
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Old 01-19-11, 09:25 AM
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We'll say 60 watts at 14 volts max going to the headlights, so about 4.25 amps. Would that mean I need a diode that supports 4.25 amps, correct? Would these work:
6A, 50V Rectifier Diodes (4-Pack) - RadioShack.com
 
  #6  
Old 01-19-11, 09:34 AM
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I dont believe any diodes are required. Wire the relay normally closed contacts in series with the factory headlight trigger. When the relay is energized it will break this contact.

I install remote starters which power the parking lights and tap into the + parking lights and do not diode isolate anything. No problems whatsoever
 
  #7  
Old 01-19-11, 09:40 AM
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Originally Posted by Danny7633 View Post
I dont believe any diodes are required. Wire the relay normally closed contacts in series with the factory headlight trigger. When the relay is energized it will break this contact.

I install remote starters which power the parking lights and tap into the + parking lights and do not diode isolate anything. No problems whatsoever
Could you make me a quick diagram of what you mean by "Wire the relay normally closed contacts in series with the factory headlight trigger."? Or do you mean what I already have done in my diagram (minus the diodes)?
 
  #8  
Old 01-19-11, 09:57 AM
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assuming you are using a SPDT relay

go to the headlight switch and find locate which wire controls the headlights. Cut that wire. connect the cut wires as follows: load side (headlightside) to 30, and the headlamp switch side to 87. Under normal conditions these contacts will be closed (continuity). If they are a neg trigger wire 87A to -. If they are a positive trigger, wire 87A to +. Then wire your coil 85 and 86. What will trigger this? Negative or pos? Place your trigger on 85. If your trigger is -, connect 86 to a + source and vice versa. When your trigger is energizing the relay, it breaks the oem headlamp connection and prevents backfeeding
 
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Old 01-19-11, 10:13 AM
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Originally Posted by Danny7633 View Post
assuming you are using a SPDT relay

go to the headlight switch and find locate which wire controls the headlights. Cut that wire. connect the cut wires as follows: load side (headlightside) to 30, and the headlamp switch side to 87. Under normal conditions these contacts will be closed (continuity). If they are a neg trigger wire 87A to -. If they are a positive trigger, wire 87A to +. Then wire your coil 85 and 86. What will trigger this? Negative or pos? Place your trigger on 85. If your trigger is -, connect 86 to a + source and vice versa. When your trigger is energizing the relay, it breaks the oem headlamp connection and prevents backfeeding
I understand what you're saying now, I have an idea that slightly modifies this. I'm going to re-make the diagram and post shortly. Thank you for the advice.
 
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Old 01-19-11, 02:56 PM
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After you editted your post I understood it better and turns out I believe I did exactly what you recommended. Here is the new diagram but does anyone think the 2 amp fuse is necessary? Any other fuses I should include?

http://img543.imageshack.us/img543/6...knewrelayr.jpg
 
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