Go Back   VetteMOD.com > VetteMOD Technical Discussion > Electrical & Ignition

Reply
 
Thread Tools
  #11  
Old 05-19-2020, 10:14 PM
BBShark's Avatar
BBShark BBShark is online now
United States | Garage Monkey
 
Join Date: Mar 2008
Location: Right here
Posts: 4,615
My Photos: (327)
Default

I like the idea of a soft start. But it's beyond my abilities. I did have both fans triggered by separate switches so at least it will be highly unlikely that they both turn on simultaneously.

After I was done with mine a friend asked me if I used diode protected relays. I never even heard of such a thing. So, I searched the internet for information about diode protected relays for radiator fans. Despite the incredible amount of "information" I found, I don't think I know anything more that I did a month ago.

I trust your opinion on this. Do you know if relays with diodes are needed?
__________________
Reply With Quote
  #12  
Old 05-21-2020, 02:39 AM
69427's Avatar
69427 69427 is offline
United States | The Artist formerly known as Turbo84
 
Join Date: Mar 2008
Location: Clinging to my guns and religion in KCMO.
Posts: 2,840
My Photos: (3)
Default

Quote:
Originally Posted by BBShark View Post
I like the idea of a soft start. But it's beyond my abilities. I did have both fans triggered by separate switches so at least it will be highly unlikely that they both turn on simultaneously.

After I was done with mine a friend asked me if I used diode protected relays. I never even heard of such a thing. So, I searched the internet for information about diode protected relays for radiator fans. Despite the incredible amount of "information" I found, I don't think I know anything more that I did a month ago.

I trust your opinion on this. Do you know if relays with diodes are needed?
Relays with diodes are more flexible regarding the switch that tells the relay to turn on, and are preferred when available. The winding part of the relay acts just like a miniature ignition coil when connected to a mechanical switch (which acts like a set of distributor points) or a transistor. When the mechanical switch is opened, the magnetic field in the relay winding collapses, causing a high voltage spike across the switch (just like a set of points will arc if the condenser isn't there). The diode, connected across the windings, lets the relay winding current recirculate through the windings, causing the magnetic field to collapse slower, reducing or eliminating the arc. This protects the contacts of the control switch (the fan temperature switch, for example), or the transistor in an electronic fan controller.

At a minimum, the relays should have a resistor across the relay windings (to allow a recirculation path), but a diode is certainly preferred.

Is there a "schematic" of the relay internals printed on the housings of the relays you're using?
Reply With Quote
  #13  
Old 05-22-2020, 04:23 PM
BBShark's Avatar
BBShark BBShark is online now
United States | Garage Monkey
 
Join Date: Mar 2008
Location: Right here
Posts: 4,615
My Photos: (327)
Default

That makes sense. The relays I am using do not have a diode.

It would be difficult to replace them at this point but probably easier at this point that trying to figure out if the fans are working or not a year from now. Thanks Mike.
Reply With Quote
  #14  
Old 05-24-2020, 01:36 AM
69427's Avatar
69427 69427 is offline
United States | The Artist formerly known as Turbo84
 
Join Date: Mar 2008
Location: Clinging to my guns and religion in KCMO.
Posts: 2,840
My Photos: (3)
Default What's the function/reason for the big wires?

Well, I'm running some wires for the electric fan, and while looking over the topography of the underhood wiring (to try to keep the wires as short as possible, and not running both left and right), I noticed the (if I'm correct) horn relay under the left fender. There's some pretty healthy size red wires going to it. Merely asking out of curiosity (as I haven't had the opportunity to look at the wiring diagram in my service manual yet), but what function is going on at that point that requires that big size wires?

Thanks for any enlightenment.
Reply With Quote
  #15  
Old 05-24-2020, 09:53 AM
BBShark's Avatar
BBShark BBShark is online now
United States | Garage Monkey
 
Join Date: Mar 2008
Location: Right here
Posts: 4,615
My Photos: (327)
Default

Thats how power is distributed through the car. Red wire goes from the starter solenoid B terminal and another from the alternator to the horn relay.
Reply With Quote
  #16  
Old 05-24-2020, 08:10 PM
69427's Avatar
69427 69427 is offline
United States | The Artist formerly known as Turbo84
 
Join Date: Mar 2008
Location: Clinging to my guns and religion in KCMO.
Posts: 2,840
My Photos: (3)
Default

Quote:
Originally Posted by BBShark View Post
Thats how power is distributed through the car. Red wire goes from the starter solenoid B terminal and another from the alternator to the horn relay.
Thank you!
Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 03:24 PM.
 


Design by: vBulletin Skins Zone
Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.