Ok to use this terminal for " 12V Ignition " source?

[AZ59apacheguy]

So I am ramping up for my electric fan install and have question about hooking into "12V ignition ". The picture below shows where relay 302 resides in the fuse block. Per owners Guide, this relay controls " Trailer Tow Battery Charge Relay ". I am not using this function and there was no relay there to begin with. I would like to use the one terminal on that relay socket for " 12V Ignition " source for my fan controller. I have verified ( looking at the picture ) that the top terminal is an " ignition source ". I do not want to have to rip into my dash and splice wires to accomplish this. Does any one see an issue with me using this terminal for ignition source? Thanks

 

[stamp11127]

What is the controllers current draw in amps? You size the wiring and fuse to the current draw(load) plus a few amps for margin.

 

[AZ59apacheguy]

Hi. There is two inputs into the controller. Terminal #1 goes straight to the battery terminal, this wire ( 20 AWG ) requires a 2A fuse inline. Terminal #2 is the " Ignition " feed , I believe it's just used to tell the controller to " wake up ", there is no fuse requirements on this wire ( 20 AWG ); should I fuse it just to be safe? The controller is capable of supplying currant draw from the fans up to 125A, my fans will only require less than 50A max. Your thoughts

 

[AZ59apacheguy]

Here is the link to their webpage if interested:
http://www.autocoolguy.com/#!home/mainPage

 

[stamp11127]

Adding a fuse would only be necessary if the fuse protecting the circuit you are branching off of is rated higher than what the controller draws on that ignition wire.

Example: If the source circuit is protected by a 30amp fuse but your new branch circuit will only draw 5amps, then you are not protected. In this case you need to fuse it. You are fusing a 5 amp circuit with a 30amp fuse.
The flip side of this with the same scenario is the main circuit draws 25amps, the factory fused the circuit with a 30amp fuse. You now add a branch circuit that draws 7.5amps. Total draw on the circuit is now 32.5amps. You will start blowing fuses when both circuits are on. Plus you have eliminated the built in buffer from a slight overload of the main circuit.

Connect per their install instructions then read the current draw on that circuit and fuse appropriately.

 

[AZ59apacheguy]

So what do you think about me using the terminal on that solenoid receptacle for " ignition sourced " 12V? In the first pic, it's the one at the top ( 12:00 ), in place where the Trailer Tow Battery Charge Relay is supposed to reside

 

[stamp11127]

Could you tap a branch circuit there - yes. But that isn't the best way to do it. If the battery junction box has a positive lug on one end you could tie the circuit in there and run the wire with the existing harness, just zip tie it in place.

For terminals, use only the higher quality "crimp - solder - heat shrink" type. These are almost indestructible if attached correctly but cost more than the junk terminals most auto parts stores carry.

 

[AZ59apacheguy]

Could you tap a branch circuit there - yes. But that isn't the best way to do it. If the battery junction box has a positive lug on one end you could tie the circuit in there and run the wire with the existing harness, just zip tie it in place.

 

[AZ59apacheguy]

Hi, thanks for the reply. Could you explain why that's not the best method of doing it this way. Also, hooking the " ignition feed wire " to the positive lug wouldn't be considered iginition power.

 

[stamp11127]

From a professional standpoint there is nothing to secure the wire to inside the box other than where it plugs in and then at the harness. Neatness counts.

Do you have the wiring diagrams for the power distribution?

I'll give more info later, been driving all day picking up another project car - I'm not 18 any more.....this Ga heat & humidity is zapping the snot out of me today.

 

[AZ59apacheguy]

LOL. I hear what your saying about the heat, we in AZ know ALL about that, just not the humidity..

 

[AZ59apacheguy]

I'll give more info later, been driving all day picking up another project car - I'm not 18 any more.....this Ga heat & humidity is zapping the snot out of me today.

Any chance you could give an update? Thanks

 

[SlabPlox]

on one of the ''repair'' i did on my expedition i needed a 12v switched source, this is what i used: https://www.napaonline.com/napa/en/p/BK_7822226/

 

[stamp11127]

I'll update this probably later tonight.

I've been cleaning up by my recent "steal" to see if it is worth fixing or using as a donor car for parts. After a quick wash it turns out to be in better shape than the way it looked.

Change of plans...going to swap in a manual while searching for a diesel donor for the other "project".

 

[stamp11127]

To most people this doesn't matter, BUT....from a professional standpoint you want to have separate circuits for the various loads, keeping branch circuits to a minimum. In the event of a problem you lose only that circuit, not the additional add on branches. When possible you always try to source power from a hot lug then fuse accordingly.

Getting power from the trailer relay socket will work and feel free to do so, but in the future should you decide to enable the tow function and use the relay, you have a slight problem.

Here is what to avoid:
https://www.google.com/search?q=school+bus+wiring&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjpp--BoY3OAhVF4CYKHY0pAxoQ_AUICSgC&biw=1120&bih=617#imgrc=zh1bHTk1Euy_2M:

Compared to the professional layout:
https://www.google.com/search?q=bluebird+school+bus+side+panel&biw=1120&bih=617&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiutqTHoo3OAhXG3SYKHTTwDyIQsAQIGw#tbm=isch&tbs=rimg:CbmSULZHrtTqIjiWD0VSAI0ovOqCqTWMHEuPxTng7icCsKU68NM945pqqmVQPD8FOgC7-Qbk34nrVQ4cTcvLm4R3OyoSCZYPRVIAjSi8EZO2UPM_1_1b3KKhIJ6oKpNYwcS48RYnQeZB1_11ToqEgnFOeDuJwKwpRHSV5zWMvlUzioSCTrw0z3jmmqqEe0hUS2wEwM2KhIJZVA8PwU6ALsRVX2TYJkS6-AqEgn5BuTfietVDhHSV5zWMvlUzioSCRxNy8ubhHc7Eba9lUTv4si7&q=bluebird school bus electrical panel&imgrc=uZJQtkeu1Op7YM:

Do yourself a favor, and trust me on this, do not use the crappy crimp only connectors that the run of the mill auto parts houses have. Only use the crimp-solder-heat shrink connectors. Yes they are more expensive, but done correctly they are trouble free.

 

[AZ59apacheguy]

Do yourself a favor, and trust me on this, do not use the crappy crimp only connectors that the run of the mill auto parts houses have. Only use the crimp-solder-heat shrink connectors. Yes they are more expensive, but done correctly they are trouble free.

Thanks to both of you for the reply's. I will definitely not turn the truck into something like those photos in the link you provided, I like my work neat and tidy. I just order an assortment of those crimp/solder/heat shrink style connectors, should have them same day from amazon prime
I am going to start a thread on the electric fan install for my truck, since I have found no threads with anyone using a Autocool III. I'll post it when I am done

 

[stamp11127]

If you haven't used those connectors before they follow a similar procedure as the junk connectors but after crimping you heat the connector with a torch. This will melt the solder and shrink the heatshrink tubing, bonding it to the wires insulation.

 

[AZ59apacheguy]

If the battery junction box has a positive lug on one end you could tie the circuit in there

Is this the battery junction box you were referring to? If it is, can I use this lug to power the fans and controller instead of going straight to the battery terminal itself?

 

[stamp11127]

Nope. That is the starter relay. You could test the lug in the foreground to see if it is "hot in run" though.

 

[AZ59apacheguy]

Nope. That is the starter relay. You could test the lug in the foreground to see if it is "hot in run" though.

You mean the one up in front of the picture? That's my fused junction box to hook up power to both the fans and fan controller. Should I just hook this up to the battery terminal then?