Wiring a 5 pin relay "backwards"? (1 Viewer)

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I'm running electric fans on my LS swapped 80 series. And they pull alot of power - nominally 25A, but they pop 30A fuses. Uncomfortably close to the limit for the run of the mill 30/40 relay. a thought confirmed by some forum posts indicating relays weren't lasting to long with this fan.

So I picked up some heavier duty 80/60 relays, which also happen to be waterproof, meaning that the pigtail wires are sealed into the plug.

Which brings me to the question. Pretty much every relay wiring diagram you find shows the battery on pin 30 and the load on pin 87 (Normally Open). Example:

output-for-a-relay.jpg

relay_5pin_changeover_schematic.gif
This leaves pin 87a (Normally Closed) hot when the load is not in use. I typically just de-pin the 87a wire from the pigtail so it can't flop around and short out. But that's not so easy with this unit.

I could just tape up the end of course, but electrical tape doesn't last forever. So I was thinking, why not wire it "backwards" and put pin 30 on the load side and pin 87 on the battery side. That way 87a is never hot.

Electrically, it should be fine of course. I just wonder if there's something in the mechanical design of the relay that will make this prone to earlier failure or such.
 
that will be fine it doesn’t matter.
Also, a 40 amp relay shouldnt have any issue with a 25 am fan
Post up a pic of what relay you chose I am interested to see what it looks like
 
Here you go - that's a typical 30/40 relay on the left. The 60/80 definitely has more weight to it as well. The pinout is identical - if it weren't for the shroud, the pigtail from other relay would plug in fine. So I don't have to carry anything special as a spare.
IMG_20210307_133739.jpg


I haven't had any trouble yet, but I've only put on about 150 miles so far. But the fans are definitely pulling north of 30A - I'm running 40A fuses, since 35A are a little harder to come by.

Here's the pigtail - the wires are kind of potted in that blue plastic.
IMG_20210307_133809.jpg
 
have you checked to see if all your wiring is fine at 40A?
 
have you checked to see if all your wiring is fine at 40A?
Yea, I ran 12ga and it's only 3 to 4 feet from the fuse.
 
your fans are pulling more then 30amp each?? What fans are they? They should be at least 350watt each if they're pulling that many amps so hopefully you're getting your moneys worth out of them.
 
your fans are pulling more then 30amp each?? What fans are they? They should be at least 350watt each if they're pulling that many amps so hopefully you're getting your moneys worth out of them.

I'm assuming it's inrush current rather then steady state that's blowing the fuses, but I haven't tried to measure it.
 
what ECU are you using? You could PWM them, what be a neat project for you
O7 green/blue
I've seen kits for that, but I thought they had their own temp sensor. How does the ECU play into that?
 
O7 green/blue
I've seen kits for that, but I thought they had their own temp sensor. How does the ECU play into that?

I know it’s possible to do it with a stock ECU as there were LS Gm’s that had PWM fans, you’d have to segment swap your ECU to one of those models and maybe change some pinouts. Not sure as I haven’t done with this stock ECU. You can use a fan control module from a Dodge Caravan as a PWM controller to control any fan (or any DC motor) but you still have to feed it a PWM frequency duty cycle percentage
 

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