Electrical Help on Auxiliary Fuse Box

[Longhorn425]

Hi all,

I've been having some electrical issues lately on my aux fuse box.

Originally my setup worked flawlessly, but something happened that caused it to shit the bed, and now nothing works.

I'm running:

0 Gauge wire from + Battery to 'Battery' on a 100 AMP Circuit Breaker


8 gauge wire from 'Aux' C.breaker to 30 Relay

8 gauge from 87 on Relay to + on Aux Fuse box

16 gauge from 86 on Relay to internal IGNITION Fuse

16 gauge from 85 to - on fuse box (also has a 0 gauge wire running to battery)

0 gauge wire from Fuse Box to - Battery


I checked all accessories with a direct connection to the battery and they all work. I also checked the voltage and am getting 12V throughout the entire fusebox.

I thought it was a bad ground, but I played with the - terminals a million different ways and still no luck.

Has someone run into the same issue and have a solution?

 

[AMLOR]

Hi all,

I've been having some electrical issues lately on my aux fuse box.

Originally my setup worked flawlessly, but something happened that caused it to shit the bed, and now nothing works.

I'm running:

0 Gauge wire from + Battery to 'Battery' on a 100 AMP Circuit Breaker


8 gauge wire from 'Aux' C.breaker to 30 Relay

8 gauge from 87 on Relay to + on Aux Fuse box

16 gauge from 86 on Relay to internal IGNITION Fuse

16 gauge from 85 to - on fuse box (also has a 0 gauge wire running to battery)

0 gauge wire from Fuse Box to - Battery


I checked all accessories with a direct connection to the battery and they all work. I also checked the voltage and am getting 12V throughout the entire fusebox.

I thought it was a bad ground, but I played with the - terminals a million different ways and still no luck.

Has someone run into the same issue and have a solution?

I'm not an electrical engineer, and i don't even play one on TV, but based on the way I have always set up relays the pins are used as follows:

87 is battery power IN
85 is ground
86 is switched power IN (to activate the coil)
30 is battery power OUT to accessory

A relay is just a switch. A low power circuit (ignition on for example) goes to the internal coil through the 86 pin. the corresponding ground pin is 85
Once the coil is switched ON (ignition on) the power flows through the coil, allowing battery power to flow from the 87 pin to the 30 pin and out to the accessory.
I think you MAY have smoked the relay. I looks like the 30 and 87 are reversed in your diagram. I will stipulate that they may work perfectly well this way.
However, how much amperage is the battery putting out? Using 0 GA wire carries a S**t load of power. Shutting that power off is a serious shock load on the relay coil. I see no diode between the 86 and 85 pins to absorb the spike of the collapse of the coil's electromagnetic field, which will cause damage to the device controlling the coil.

As an example only, I have a roof mounted light bar that will pull 40A. I use a 70A relay with a clamping diode mounted in reverse bias across the relay coil. I use 16ga with a 1A fuse to activate the relay through a manual switch. I run 8ga from a powered positive buss with a 60A ANL fuse. I also use 8ga up to the light.

Try replacing the relay with a new one and see if it all starts working again. personally, I would switch the 30 and 87 from the way your diagram shows, and find a relay harness with a diode across the 86/85 coil trigger.
Good Luck,
AMLOR

 

[Longhorn425]

Thanks for the advice!

I did check everything again. I'm oddly getting 18V at the circuit breaker when the IGN is OFF; 12v when IGN is ON. Weird.

But I checked all my wiring, and finally found the culprit...

Due to the extreme heat here in CA, my 0 gauge + wire terminal completely melted off the battery. Had to make a new one and solder the sh!t out of it.

Everything works now (but I feel really stupid)!