Correct Wire Gauge for Onboard Air?

[Snippy]

Hi All,

Looking to mount this ironman air compressor (same one as the smittybilt I think) in the rear right corner of the bed.
The specs are 12-13.5v and 45A.

I don't have a lot of electrical knowledge so I'm trying to understand what gauge wire I'd need. Using this calculator I inputted the above specs, accounted for 2% voltage loss and 25ft of cable.

It recommends 2awg cable. I know thats a thick cable, so is that correct. Additionally, I feel like I'd need to add a fuse near on the cable near the battery? Thanks

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[EricR]

You seem to be heading I the right direction.

Based on the small amount of experience I gained adding lithium batteries to our RV, here are some thoughts that might help as you determine the correct wire gauge:

• Looking at the specs I didn't see the actual amperage draw, just that it had a 45A fuse. See if you can get a PDF of the manual or otherwise confirm the actual draw (it is probably 30A or so).
• Can you make the run in less than 25 feet? Maybe make your intended wire run with some twine and measure it. Use this in your calculations. Even 2-3 feet less could help.

For example, for a 22 foot run at 13.8V and 30A the calculator shows you could use 6 guage wire.

Regarding a fuse, look into a MRBF fuses (Marine Rated Battery Fuse) and a related fuse block/holder. Very compact and some of the fuse blocks available mount right on the battery terminal bolt.

To my understanding the fuse should be 125-150% of the amperage draw of the device being powered. You are protecting your wire run, not the device.

Buy an extra fuse and put it in your tool box or glove box. You won't find MRBF fuses at Wamart or a typical auto parts store.

-Eric

All of the above is non-professional feedback -- use at your own risk.

 

[Bluesman]

Here is a good marine guide that should offer some insight.

https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

 

[My 2ND Ford]

Hi All,

Looking to mount this ironman air compressor (same one as the smittybilt I think) in the rear right corner of the bed.
The specs are 12-13.5v and 45A.

I don't have a lot of electrical knowledge so I'm trying to understand what gauge wire I'd need. Using this calculator I inputted the above specs, accounted for 2% voltage loss and 25ft of cable.

It recommends 2awg cable. I know thats a thick cable, so is that correct. Additionally, I feel like I'd need to add a fuse near on the cable near the battery? Thanks

Why don't you mount the compressor in the front of the bed. You will save on wire cost and the compressor will be less in the way. Yes to the fuse mounted nearest to the battery and I would stick with the 2 gauge. I worked for NAPA and we always carried this gauge, along with the connectors in stock. The wire is available in black and red and it is very flexible. I will warn you that buying 50 ft of cable, along with the fuse block and connectors will be very expensive, unless the cost has come down. Shop around , but you want a welding style jacket on the wire. The wire ends can be crimped or soldered on, make sure you also buy heat shrink to seal the end.

 

[My 2ND Ford]

Why don't you mount the compressor in the front of the bed. You will save on wire cost and the compressor will be less in the way. Yes to the fuse mounted nearest to the battery and I would stick with the 2 gauge. I worked for NAPA and we always carried this gauge, along with the connectors in stock. The wire is available in black and red and it is very flexible. I will warn you that buying 50 ft of cable, along with the fuse block and connectors will be very expensive, unless the cost has come down. Shop around , but you want a welding style jacket on the wire. The wire ends can be crimped or soldered on, make sure you also buy heat shrink to seal the end.

I just looked at the ironman compressor and you will spend more for the wire than the cost of the compressor. I would just lengthen the wire that comes with it and keep it portable. If you want to mount a compressor , head over to you tube and search out Big Truck Big Rv. Search for his episode on bed mounted compressors and you may get some better ideas. I thought the compressor was larger, so the probably will not need the 2awg, you may be able to use smaller gauge to save money.

 

[Snippy]

Thank you everyone for all of your feedback!

Given the length etc, I'm thinking it may be best to bolt down the compressor behind the right rear seat (where the jack usually goes).

If so, I think I could go to a 4AWG cable. The compressor's max draw is supposedly 45A as you know, and from what I read the fuse should be 1.1 - 1.5x that.

Would this 50A inline fuse holder work?

 

[Snippy]

Small update, I've been planning and think I'll be proceeding with the following:

• Windynation 6AWG Kit (I think I need less than 14ft)
• WindyNation ANL Fuse Holder + ANL Fuse (2pcs 60A Fuse)
• Anderson Power Products SB50 Connector Kit, 50 Amps, 36V Gray Housing, w/ 6 AWG, 6319 (Pair)

My Plan:

1. Remove scissor jack and mount and mount air compressor in place.
2. Cut alligator clips from air compressor and put on Anderson SB50 connector
3. Add SB50 connector to 6AWG cable on one end to connect to air compressor.
4. Connect new ground wire near air compressor (most likely one of the nearby bolts).
5. Run positive wire along bottom under door sill etc and through the firewall rubber grommet
6. Attach ANL fuse holder 6in from positive battery terminal.

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