Question about air compressor

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Oryguntroutbum

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Location
Central Oregon
I have one of the Masterflow
Style 12 volt portable air compressors. It's the kind with the jumper cable type attachments that go to ones battery.

I was thinking of cutting off the spring loaded clips and attaching the compressor more permanently to one of my AGM batteries inside my camper. In essence, I would be creating an "on board" air system.

Has anyone tried this? Any issues with keeping it hooked up to the battery?
 
Additionally, the amount of amps that the air compressor draws should be taken into account.
Most of these are very high draw ampeage units and may draw down your camper battery faster than you can believe.

When I use my 15 amp Vair air compressor, I always have the truck engine running for the entire compressor usage time and I keep the truck engine running for awhile after the compressor usage time... to top off my truck battery (either by driving, or just running the engine if not driving).
 
You could do it but as others stated, it will draw down the battery pretty fast (which take longer to charge) and you lose the benefit of moving it. I can't see the benefit.
 
I forgot about Alley-Kat's point. Viair recommends having the engine running when using the compressor. I'm using the Viair 400P.
 
I have a Viair 450P and recently added ARB on board air for my rear lockers. I much prefer the onboard air, I added a chuck outside the vehicle so I don't even have to pop the hood when using and all I have to unpack is the hose. It is hooked to the truck battery, though, and not the camper - as others have said they draw a lot of juice.
 
Oregon Troutbum....No, you do not want to setup your air compressor as you described. An air compressor draws a lot of amps. When you run a compressor attached to a vehicle battery, you run the engine so the alternator is supplying the amps, not the battery. A vehicle battery's sole job is to crank the engine. Once the engine is at idle RPM, the alternator supplies electricity to the vehicle's electrical system, not the battery. Even if you have alligator clips attached to the crank battery, the alternator is supplying the amps.

Tie an air compressor into the camper batteries and stored energy will drop very quickly. You will need shore power to restore them to full capacity.

I use an Extreme Aire compressor wired into one of my F-350's upfitter switches.

Not sure about my comments? Attach a multi meter to crank battery without engine running. A fully charged battery in good condition should register ~12.6V and rated stored amps, not CCA.

Start and idle engine, if alternator in good condition, multi meter should register ~14V. Amps should register the rated alternator output minus the amp draw of any activated electrical systems.

Ford F-250 and F-350 models have a dual alternator option for owners needing a lot of amps for installed electrical components.
 
I looked up your Masterflow. As I thought it appears to be the same as the MV50 compressor I have. They're sold under various names.


These are actually made to be hard mounted as an option. Mine came with instructions for that.

They do draw some amps But I've never felt the need to have the engine running when airing up my off road tires. It's never been a problem. However I personally would hard mount under the hood off the truck battery. Not in the camper off that battery.

I had thought about hard mounting mine in my trail truck. A while back I bought one of these for inflating tires around the house.
http://www.aircompressorsdirect.com/Campbell-Hausfeld-FP2048-Air-Compressor/p328.html?gclid=CJqLs9j_8M4CFY07gQodoRcNkg

I figured for the price it had a limited lifespan and when the compressor died I would use the pressure tank on the truck compressor. A small pressure tank will greatly increase what you can use a small compressor for.

Other things things to think about. Those MV50 compressors use a non standard air fitting. Longer hoses don't just snap on. It is possible to drill and tap for a standard 1/4" NPT fitting. Many have done that.

Other things to watch for. These compressors often have a badly crimped fuse holder which makes for high resistance (the fuse and wires should not get warm) and cause them to blow fuses. I replaced the one on mine the 1st day I had it. The reed valves are also known to break occasionally. Many have used a feeler gauge blade to repair that. Otherwise a great bang for the buck.

But I think hard mounting in the camper would be limiting the use you get out of it. Better under the hood.
 
(LOL....It's funny to see how quickly this thread is going. While writing up my response I've seen at least four other replies... but I'm gonna post anyway!!!)

Other thoughts (in addition to the draw issue)

- is the location you're thinking of putting it well ventilated? I'm thinking if it's a small space it could heat up quick. Perhaps not a problem for a routine use but an issue for an extended one?

- is the space your mounting it important for other storage? (if you're taking it out, you only need reserve space for the packed-up unit. If you're going to run it in place you need to reserve space around it (perhaps), or move stuff out of the way before starting it)

- I'm seeing some Masterflow compressors online appear to have the gauge on the compressor. If that's the case with yours, does it matter to you?

- check to be sure the hose routing works (I don't think mine would make it)

- is the on/off switch vulnerable to being jostled on without your knowledge? (by shifting gear, etc)

Possible arguments for going ahead....

- the worst-case usage is expected to be light enough for the draw not to matter
- you have a great location not suitable for anything else and it would work for the compressor
 
Hmmmm...good timing on this...about to purchase the 450P to carry in truck...doubtful if it will see much use...concur with comments about why not to try and mount it inside the camper or use the camper batteries to run it..


Phil

Ps...Sagebrush, when are you going to Utah? We are planning to be in Escalante area 10-7 to 10-21. First trip there with Hawk.
 
Squatch said:
I looked up your Masterflow. As I thought it appears to be the same as the MV50 compressor I have. They're sold under various names.


These are actually made to be hard mounted as an option. Mine came with instructions for that.

They do draw some amps But I've never felt the need to have the engine running when airing up my off road tires. It's never been a problem. However I personally would hard mount under the hood off the truck battery. Not in the camper off that battery.

I had thought about hard mounting mine in my trail truck. A while back I bought one of these for inflating tires around the house.
http://www.aircompressorsdirect.com/Campbell-Hausfeld-FP2048-Air-Compressor/p328.html?gclid=CJqLs9j_8M4CFY07gQodoRcNkg

I figured for the price it had a limited lifespan and when the compressor died I would use the pressure tank on the truck compressor. A small pressure tank will greatly increase what you can use a small compressor for.

Other things things to think about. Those MV50 compressors use a non standard air fitting. Longer hoses don't just snap on. It is possible to drill and tap for a standard 1/4" NPT fitting. Many have done that.

Other things to watch for. These compressors often have a badly crimped fuse holder which makes for high resistance (the fuse and wires should not get warm) and cause them to blow fuses. I replaced the one on mine the 1st day I had it. The reed valves are also known to break occasionally. Many have used a feeler gauge blade to repair that. Otherwise a great bang for the buck.

But I think hard mounting in the camper would be limiting the use you get out of it. Better under the hood.
Click to expand...
X2 I have mine hard mounted under the hood. Ron
 
As someone has stated a very timely topic!

I am thinking of following Dave (of American Adventurist fame) and installing an Air Lift kit to raise the rear end a bit. The Air Lift kit does have an option for an on board compressor but I would like to make sure that the compressor can also be used to pump up the ties when needed..
 
I too have the same comment as Old Crow. Those things heat up and you need ventilation when running. Even under the hood mount want to pop the hood to cool. Under hood mount could get heat soaked if it is hot and performance drops when they are too hot.

I would not have a problem hard mounting them if you have:
Good ventilation around the compressor.
Have proper wire size to battery and minimize length of wire for voltage drop.
Have hoses that will reach all 4 tires and a trailer if you are towing.
Storage area for said hose and accessories.
 
Like others have said, I would not wire it to the camper battery(ies). Underhood or somewhere else pulling power from the truck battery(ies) is the better bet. Even with two big starting batteries I start the truck before airing up. Much easier to start the engine then than after you've drawn the batteries down too far.

We carry an MV-50 as a back-up, but have a bigger DC compressor mounted under the truck bed on the side of the frame forward of the rear left tire. It pulls power off the 6 ga. power to the camper, but unless the VSR is closed it can only pull from the truck batteries. Power for the pressure control circuit is off the IGN switch. Heat comes not only from the compressor itself, but also from the discharge air. I used 3/8" copper tube to create a heat exchanger for the discharge air.
i-FLthQ6t-L.jpg


I used 3/8" Push-to-Connect DOT Air Brake tubing and fittings from mcmaster.com to put an air hose QD at the front and the rear of the truck.
 
Lol. Thanks for the replies. Didn't expect so many responses. I guess I should have clarified that the compressor will rarely be used. Only for air bags and if I ever need to air down/up tires for sand or mud.

I am leaning toward the hard mount under the hood. The current set up is a little bit of a pain to get it out for a minutes worth of air. Thanks for the responses.
 
My Viair compressor looked weather resistant so I placed it under the truck along with a 2.5' gallon tank. Still need to do the plumbing and electrical wiring. To be followed by the ARB rear locker.
 

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It's hard to tell in the pics, but if that unused fitting is the air inlet I think it's too small. Adding a filter and/or remote mounting it is a great idea, but use as big of a hose as you can make fit. Small intake hoses of fittings will strangle the compressor and make it work much harder than it needs to.
 
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