On Board Air blowing fuses

Well crap...

“If it is necessary to mount the air compressor further away from the battery in the bed of your truck, use a minimum 8AWG positive lead wire for remote installation.”

damn it.

 

If they gave you 20' of 12 gauge wire, it shouldn't make a difference where you mount it. Now, if you had to extend the loom for whatever reason, then it would advisable to upgrade to 8 gauge wire. 20' of 12 gauge wire will still have the same resistance whether its straight laid end to end or curled up in a spool.

-J

 

You need a fuse rated for more than the pump draws, not exactly what it draws.... I use a 50a breaker for my 30a compressor. All you're really doing is protecting the wires against a short.

You didn't mention an on/off relay. Most cheap switches will fuse shut switching a 30a load. Maybe it's in the grey housing?

 

There is a on/off relay in the grey pressure switch. Off at 145psi. On at 110psi. I have it wired to a manual remote switch that connects into the pressure switch - it’s part of the air gauge display at the far right in the first picture.

and here:

At this point, it is working fine with a 25Amp fuse. I have a spare 25 and a spare 30. I’m leaving it as is.

Thanks everyone for your input!

 

I realize things seem to be working now, but I am going to encourage you to go to a) thicker wire and b) a circuit breaker instead of a fuse. I initially ran 6g for an ARB dual in the bed and had the exact same problem with fuses. Ultimately I ran 4g to the bed with a breaker and havent reset it since.

The lesson i have learned when it comes to wiring something like this is that it's generally better to spend the extra couple bucks on thicker wire given the time and effort to run power from the battery to the bed. Honestly I wish I had gone with 0g so I could support another secondary fuse panel in the bed for my bed camper setup. Just my .02 cents.

 

Can you hear the pressure release just as the compressor stops?

 

no...pretty sure it doesn’t have one. Probably why it was a good deal.

 

OP you're about 3 feet too long with 12 gauge wire, put a 30 amp fuse in it and leave it as is forever.

 

when the 25Amp blows...the 30Amp spare is in the coin cubby ready and waiting

 

Lol...I know it's been suggested by other members and I'm not saying it won't work, but you do know that replacing a blown fuse with a bigger one is like the epitome of what you're not supposed to do, right? I'm not trying to be a jerk here, but the whole point of the fuse is to make sure you're not drawing more power than the wires can handle. I mean you should be fine going from 25 to 30, but if the 30 amp fuse starts blowing, sticking in a 40 or 50 amp fuse is probably not the BEST solution and could potentially result in the truck fire you're trying to avoid. Going back to the wiring chart that was previously posted, 20ft of 12G wire with 25 amps is the upper limit of what the wires can handle. Thicker wires is the answer...not a higher amp fuse.

 

one more thing to consider, if you continue to blow fuses, you may want to try to run a fused power wire directly from the battery to the compressor (bypassing the fuse block). It looks like a blue sea fuse block which is only rated at 30a per terminal. if the compressor actually maxes out at 28a you should be fine but if it happens again, id bypass the fuse block just to rule that out as a potential bottleneck.

 

Do not just throw a bigger fuse on it and expect everything to work out okay.

You're essentially taking a wiring system that maxes out at 25amps (based on the wire gauge you have, and the chart posted earlier), and going to a 30 amp fuse, which means you'll max out the wire before the fuse blows.

I can't say why you were given 12g wire in that kit, but that honestly is a bit undersized, especially if you're throwing a 30 amp fuse on it. That chart is really showing you the minimums, when in doubt, go bigger.

I'd run at least 10g, probably 8g if there's ever a chance you'd upgrade to a bigger 40a compressor.

 

This is a really good point too...I would not recommend running something like a compressor off a blue sea fuse block. Run it directly to the battery with proper size wires and fuses or circuit breaker.

 

lol...yeah I have questionable judgment but I get it. I actually have 2 spare 25Amps and 1 30Amp in the coin cubby.
And three fire extinguishers in my truck. You can see one in the previous picture.

I will likely only use the air system a few times once a year to use the blow gun to blow the dog hair out of the bed but it’s fun to hit the little switch and see the gauge needle rise.

 

Doesn't really matter if you have 20 fire extinguishers.

A few feet of 8g wire will always be cheaper than repairing fire damage.

 

^ This

 

Maybe I'm being a bit pedantic, but that's not the main purpose of a fuse. Fuses have tons of uses protecting equipment from overloading, so a power surge or overloaded motor doesn't blow your multi thousand dollar PCB. I'm guessing a compressor motor has a little more tolerance for over amperage than other components, but there is more to picking a fuse than what wiring you are using.

Generally if you aren't an EE(or at least studied in the field) and have some very specific knowledge on the electronics you are dealing with, the best course would be to ask the manufacturer what their recommended fuse is. Then figure out your wiring etc. based on that. It seems half the advice in the thread is working backwards.

All that being said if the manufacturer included a 40A in the kit I'm not sure why this is a thread.

 

So I think we finally know enough to understand the issues here. First off, this needs to be a relayed harness, not direct wired through a switch. As mentioned, It should be directly off the battery, not the fuse block. With the distance between the battery and the bed, it should be wired with a minimum 6 awg wire, and 4awg would be better. That size is not so much for safety, but to prevent a voltage drop. A voltage drop will cause the compressor motor to run hotter, and reduce the performance of the compressor. It will also shorten the life of the compressor motor. That wire should run through a minimum 80A relay. The switch is only used to activate the relay, and the wires from the switch to the relay can be 16awg. There are lots of wild guesses in this thread about wire size. There is only one right answer. Measure the length of the wire from battery to compressor. Find the amp draw of the motor. Plug the numbers in here using 2% drop: https://www.wirebarn.com/Wire-Calculator-_ep_41.html That is the true size you need.

You should have a release valve, also called a "blow-off valve" or "unloader valve". Whoever sold you the kit should know if one is there or not. If not, get one. You can find mechanical valves or electronic. Here is a good electronic valve (recommended): https://www.extremeoutback.com/product/electronic-blowoff-valve-12v-application/ Here is a mechanical valve: https://www.ebay.com/itm/CA-12-Load...8-Self-Unloading-Check-Valve-New/281915550936 This improve the function of the unit and keep it running a LOT longer!

 

Replacing an undersized fuse with a correct size fuse poses zero threat of a fire.

It probably came with a 40 amp fuse and 12 gauge wire because of the electrical surge a previous poster commented about. Wire ratings are for continual amperage draw and not spikes in the amperage draw. A 40 amp fast blow fuse (standard vehicle fuse) will blow just as quick as a 30 amp fuse with a dead short in the system with a 12 gauge wire. His truck has about 17' of wire and not 20'. It's amperage draw is 28 while running with a max load and not 25 amps. Lastly, a thicker wire will do absolutely nothing to prevent blowing a fuse that's too small to begin with.

Bypassing the fuse block with that amount of current draw is an excellent idea which I personally would do but I don't think it's a mandatory must do job.

All of these fire comments have me laughing my ass off. The OP's situation ain't even close to anything near catching fire lmao!!! You're fine OP, leave it.

I've completely rewired 10 cars, everything from the headlights to the taillights and everything in between. I've completely rewired at least 15 boats, probably over 50 trailers, easily over 7,000+ car stereo amplifiers, several winches, probably over 20 off road lights, 10,000+ car alarms...

Oh f___, an engineer posted lol I'm out, they're the freakin worst... oh snap he's bragging about his degree lmao see ya'!