What Wire/Cable for my compressor

[barlowrs]

OK, well for my OBA compressor I am planning on running 6 AWG wire from the batt to the back of the truck. Unfortunately, this means I need a lot of it. I have a few questions:

1. For my aux fuse block I used 4 AWG marine grade cable, while it is great, it is very stiff, and expensive. Is there a better solution for my compressor project? Something more flexible, or cheaper? Would welding cable (more flexible) or audio cable work? Where is a good place to get it cheap?

2. With my winch, I ran power and ground all the way to the battery. For the compressor, do I need to run the ground all the way back to the batt as well, or can I ground it on chassis? This will save me 20ish ft of 6awg wire if I don’t need to?

THANKS!

 

[MotoDave]

I assume by marine grade wire you're referring to tinned wire. Its nice stuff, but not cheap. I've found its WAY expensive at my local marine store, 3x what I can find it for online.

Most OEM wiring will be regular 'primary' wire. For the most part I tend to think the electrical engineers at the OEM's know what they are doing better than I do, and I've had no problems yet using it.

Welding cable should be more flexible than battery cable, not sure of the price difference.

Lastly you should be fine grounding to the nrearest good ground point, that's how my compressor is run and I have no issues. I think its only for noise reasons that electronics are typically grounded back to the battery.

 

[slomatt]

Depending on how much current your compressor draws and how long the power wire will be you can likely use 8 gauge wire. I've had good luck with KLMX kable from KnuKonceptz on other projects.

http://www.knukonceptz.com/productMaster.cfm?category=KLMX Kable

Here's my OBA install that uses this wire.

http://wwww.blankwhitepage.com/automotive/2000-toyota-4runner/on-board-air

- Matt

 

[Life_in_4Lo]

Nice clean install slomatt!

How long does it take to air up a tire w/ that compressor?

 

[Antichrist]

What's the current draw of the compressor?

 

[Token]

Cheapest route I found was to get an audio amp wiring kit.. Typically you can get 8awg or 4awg and it comes with a inline fuse for under the hood.

I was putting a battery in the back of the truck as well, so I went with 4awg and ALSO put in an inline 80amp circuit breaker. Gives me the ability to disconnect the rear battery from the rest of the truck (except for the compressor which is also in the back)

Do NOT worry about the quality of audio wiring kits.. Those guys are brutal on wire specs.. For a 4awg kit you'll spend at least $80.. Anything you find for half that and less is crap and your 4awg cable MIGHT be a decent 10awg.. It'll look the same on the outside, but it's all jacket..

 

[Martyn]

Use 6 ga welding cable from the battery to the compressor. We use an 80 amp resettable water proof circuit breaker, place it in line as close to the battery as you can.

Ground the compressor to the chassis as close to the compressor as you can using 6 ga. Make sure you are down to good clean bare metal for the ground, in the long term bad grounds are the most common cause of compressor "failures".

Put a manual on off switch in the cab, place it somewhere you won't accidentally turn it on with you knee when you are getting in and out of the truck.

If you need parts just send me a list via e mail and I'll take care of everything for you.

 

[MotoDave]

Nice clean install slomatt!

How long does it take to air up a tire w/ that compressor?

I've got the same MV-50 compressor, i;d guess it takes me about 10-15 minutes to bring 4 33's from 15 to 32 psi. I usually end up waiting for the rest of the group to finish airing up, except for the guys that are using CO2 tanks.

 

[Antichrist]

In your other thread you said you were getting an AIM DC-7600, then looks like you settled on a Puma 1006. The latter, from what I can see, draws 30amps, the former 25.
Assuming 30 amps and a 15' run you'll be fine with #8, which will give you 0.32v drop which is fine. #6 will give you a .18v drop, and you can get #6 welding cable for a bit over $1/ft. If you're planning on hanging anything else off of it beyond the compressor that draws more then 10amp, I'd definitely go with #6.

I was putting a battery in the back of the truck as well, so I went with 4awg

Unless you have a 80amp or less alternator, or a good bit shorter run, 4ga is too small for that.

Do NOT worry about the quality of audio wiring kits.. Those guys are brutal on wire specs.. For a 4awg kit you'll spend at least $80.. Anything you find for half that and less is crap...

$80 is way too much.
It can be done with less than $25 worth of very high quality #6 welding cable.
Heck, it can be done with high quality #1 for only $62.
The price I quoted at the top for #6 is just standard welding cable which is fine if you cover it with the split loom stuff.

 

[barlowrs]

Depending on how much current your compressor draws and how long the power wire will be you can likely use 8 gauge wire. I've had good luck with KLMX kable from KnuKonceptz on other projects.

http://www.knukonceptz.com/productMaster.cfm?category=KLMX Kable

Here's my OBA install that uses this wire.

http://wwww.blankwhitepage.com/automotive/2000-toyota-4runner/on-board-air

- Matt

Nice install!...see below on current.

What's the current draw of the compressor?

In your other thread you said you were getting an AIM DC-7600, then looks like you settled on a Puma 1006. The latter, from what I can see, draws 30amps, the former 25.
Assuming 30 amps and a 15' run you'll be fine with #8, which will give you 0.32v drop which is fine. #6 will give you a .18v drop, and you can get #6 welding cable for a bit over $1/ft. If you're planning on hanging anything else off of it beyond the compressor that draws more then 10amp, I'd definitely go with #6.

Yes I got the puma, and at steady state it draws about 30A, however, I hear that it can draw upwards of 60-70A in some cases (startup, etc). For this reason I have a 80A re-settable fuse. Although for steady state, I probably only draw the 30A, becuase I am using an 80A fuse, I want my wiring to meet/exceed that so the fuse would pop before the wires get overheated. Most research I have done use 6AWG for the Puma hard mounted.

 

[Antichrist]

Yes I got the puma, and at steady state it draws about 30A, however, I hear that it can draw upwards of 60-70A in some cases (startup, etc). For this reason I have a 80A re-settable fuse. Although for steady state, I probably only draw the 30A, becuase I am using an 80A fuse, I want my wiring to meet/exceed that so the fuse would pop before the wires get overheated. Most research I have done use 6AWG for the Puma hard mounted.

#6 certainly won't hurt and if you're more comfortable with that, it's just a little extra money.

Yes, you definitely need the fuse to be higher than the maximum the compressor will draw, or else a slow blow fuse.

As for the wiring melting, if the max draw is 30amp, other than at startup, it's not going to melt even a 10ga. I doubt it would melt even with 12ga. That 60-70amp would be a spike, not anything long enough to melt the wires.
Your biggest concern is volt drop, the smaller the wire the higher the volt drop. Anything over .5v is not good for a motor if it's more than momentary.

I've seen a lot of wiring discussions over the years and very few times do I see anyone actually do any distance/draw calculations, they just say "Go with x gauge" without any explanation behind their choice.

 

[slomatt]

We hard mounted a Puma in a friends Xterra and used 4g wire, it's been running fine for several years now. If I could fit my Puma in the truck I'd much rather have used than than the MV-50.

- Matt

 

[Token]

Unless you have a 80amp or less alternator, or a good bit shorter run, 4ga is too small for that.

$80 is way too much.
It can be done with less than $25 worth of very high quality #6 welding cable.

K.. Guess I should give the reason for the extra battery.. It's an accessory thing, mostly to give a bit more boost to the compressor.. The downside of hardwiring this compressor has been a shorter duty cycle.. Not on the compressor, but the built in circuit breaker on the switch.. I'm guessing the aligator clips that used to be on the leads limited current flow a bit. Being hard wired to the battery with only 3ft of cable has cut down the line loss and the compressor can easily overdrive the 45amp breaker in about 10 minutes (the one on the box deck, not the 80amp up by the battery).

For reference, prior to hardwiring, I could fill 2 sets or 35's from 15 back to 40 psi and never have a shut down. I typically get my 35's alone from 15 to 34 or so before I get the first trip on the breaker. I've actually got an AGM battery in the garage I've been meaning to swap in, due to it being able to provide a quicker discharge rate to the compressor, as well as a faster recharge rate.. Of course I'm pretty sure the last thing I need right now is the ability to shove more current through that breaker.

Any thoughts on the best way to cure that..?? I'm all ears..

Pricing for the Amp Kits seem high, but with the cable you also get the fuse holder, which are typically another $15 or so.. Still high compared to welding cable though I suppose.. But look at that cool blue color..:bike_rider:

 

[Antichrist]

Any thoughts on the best way to cure that..?? I'm all ears..

For the battery cable, I was referring to the length of run from the alternator to the battery. 4ga will cause too much volt drop for anything more than an 80a alternator (at typical output voltage), which isn't good for battery life.

If you mean there's a 45amp breaker on the compressor itself, that's likely for thermal overload protection so you don't burn up the compressor. I assume they designed the compressor with that in mind, so you can't go too large in the size of the power lead, only larger than you really need.
As long as the cable is sized so that you don't get more than .5v drop for the length of the run and load it's drawing, you're good.

 

[Token]

If you mean there's a 45amp breaker on the compressor itself, that's likely for thermal overload protection so you don't burn up the compressor. I assume they designed the compressor with that in mind, so you can't go too large in the size of the power lead, only larger than you really need

I was reasonably certain that's what it was for.. The smaller MV50 has it's thermal protection onboard the compressor itself and is fused inline (30amp). Since there's no inline fuse here, this is most likely a circuit breaker for overcurrent protection. For some reason I'm thinking it's a 45amp breaker.