Portable compressor for my camper?

[tbone1004]

@willo for reference, running the small ~3cfm compressors will be comparable to running a pair of 15,000btu air conditioners or single 30k btu. It's NOT easy on the electrical system and it's not something that is typically recommended to be done off of inverters and battery banks. Run it off of shore power or a generator.
Also remember that the numbers we are quoting are rough RUNNING consumption, similar to the air conditioners, their startup requirements are about triple their running currents.

 

[rjack321]

The battery bank for running a 240V 3hp compressor for any length of time is going to be massive along with the inverter. Most small (3hp single phase) compressors are pulling about 18amps at 240V. In theory a 10,000-12,000 watt whole house inverter would probably work assuming it has a 30 amp 240V output. Voltage drop (and heat) is going to be a serious issue especially since you are talking almost 100amps continuous at 48V and somewhere in the 250amp range at startup. And that's for a 3hp MCH-6

The MCH-16 is 11cfm and 7.5hp. Forget using that.

A gas engine powered compressor would be lighter, cheaper, and much more portable. The battery for your solar compressor is going to weigh more than all the rest of your scuba gear, tanks and compressor combined.

 

[АлександрД]

Please, read this thread

Check this message here Early Air Fills?
Cornelius compressor.
This ours analog КПВ-1Б had powering of 27 VDC, and 340 W of the power consumption...

and this message

Just a couple of points really to register my interest in small scuba compressors and this very interesting great topic.
But first for fun. Sitting on my office desk is a very small oil free and oil less High Pressure 4500 psi bottle filling air compressors (That are capable of compressing from ambient air) and are available in both 12 and 24 and 28 volt DC Just no one has thought yet that the yacht market would be a suitable application.

The “bottle” you lot call “tanks” is the little round silver thing on the end of my finger and its purpose is, once filled to 4500 psi to be attached to a device that really does kill tanks.
I will hook it up filling a standard 80 and find out tomorrow how long it takes but I expect most of the working day.
I dare say I have a better cheaper solution we are working out for a client with a catamaran mounting the scuba compressor upside down hanging it from the ceiling in the engine compartment and has a similar requirement but not as interesting. But for now just to show there are small HP 24 volt compressors around.

The air intake filter is the small 28mm polyester white disc on the middle right side
The power socket is the small Anphenol socket lower left and the long silver and black
"coffee" flask under my hand is the HP zeolite filter assembly.
Weight is under that of a small dog 11 kilos (24 lbs)
Power wise using a 19 to 32VDC range and 28VDC nominal
Draw is 6 amps worse case (at 269 bar) and 10 amp for one (1) second on start
(Peak current on start up is 25 amps for 15 seconds when the gas heater is operative)
Current between 15 seconds and 2 minutes is 10 Amps Maximum
Current over 2 minutes and 39 minutes is 9 Amps maximum
Current after 39 minutes running drops to 6 Amps worse case
The gas heater current is 3 Amps at 28 VDC
Operational range sea level to 10,000 ft
Excursions to 20,000 ft
Survival Sea level to 60,000 ft (18288m)
(all in height altitude in case anyone is foolish enough to ask verification.
Attitude: Roll Pitch 30 degrees
Design philosophy is the same 3 stage swash plate principle as the more commercial SA-6 160 LPM 6 SCFM design just smaller.

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[Cio]

As many are suggesting, this is pretty tough to do. Powering electric motors at or near the capacity of your electrical system is a recipe for disaster, I wouldn't think fire but you will lose motors or inverters. Most generator systems are sized 4-6 x the motor load to make it work, start up on a motor is 6x running amps min.
There is also the logistics , Where do you store it and how do you get it in and out of your camper? I bring a diesel Bauer junior 2 and get it in and out of the back of a work van, pretty much ideal and still not easy, need two pretty strong people. Installing it in your camper would be nice but will be quite a project and you need to get the heat out, not easy.
An easier solution is to make a little cascade system and, you can run some clacs and if you need to squeeze a little more out, add a booster, you can find 120V sierra boosters used or run a haskel with a little tiny low pressure compressor. weight wise it will be the same but it will be in pieces so you can get it in or out easily. You can make a simple cascade manifold out of hose and line valves that could fit in a small Rubbermaid bin. (add a regulator for safety)

Make friends at a local fire house that has a remote fill option and you can probably get fills for beer and not even have to remove the tanks from your trailer. 6K compressor aren't rare and getting fills shouldn't be a problem if you just look around.

 

[willo]

Thanks everyone!

Considering the logistics of this, I too think the gas unit is the way to go for portability.
If the compressor is in the camper, I'll probably piss off people near me. If I grab a unit I can put in the back of my truck, I can run it away from the camp ground. Seems to be the way to go.

Edit: I'm still gonna mess around with the electric idea. Too much fun.

 

[rjack321]

Thanks everyone!

Considering the logistics of this, I too think the gas unit is the way to go for portability.
If the compressor is in the camper, I'll probably piss off people near me. If I grab a unit I can put in the back of my truck, I can run it away from the camp ground. Seems to be the way to go.

Edit: I'm still gonna mess around with the electric idea. Too much fun.

You have to realize that the compressor itself is basically as loud as the gas engine. Electric would not make it any quieter anyway. And yes its gonna piss people off at campgrounds, they're louder than lawn mowers for sure

 

[willo]

Exactly.

 

[Cio]

6,000 psi. D.O.T. holds 510 cu ft.
1 bottle yields, 255 cu ft usable to fill 3,000 psi cylinders, so you can fill 3 alu 80's weighs 200 lbs and can be moved by one person. (doesn't have to be removed from your trailer)
2 bottles will fill 8 alu 80's (Low bank, down to 1,500 psi; = 382.5 cu ft usable + high bank to 3,000 psi. = 255 cu ft = 637.5 cu ft available)
every bank you add to the cascade yields more and more since filling efficiency is better with more banks.

The above calcs are conservative and assume empty tanks.

I work with this stuff, your cost for air out of a small unit is very high, I only use one because I can take it from work and it costs me nothing, paying someone else who has a bigger machine and low pumping costs is the most economical way to obtain air.

Putting a comp in your truck and then driving away to listen to a motor chug away for an hour or more will get really old really fast. don't forget about the hot fill which will need time to cool down and then be topped off so if you want "full" tanks you are taking another ride or just sitting around in the middle of nowhere for two hours.

Cascade filling is quiet, will never break down, lowest upfront and operating cost and for what you want to do, makes the most sense. The only thing it lacks is the coolness factor of having a compressor, which over time will loose its appeal. Think about how much gas you really need, if you can bring it with you, it is the best way, if it really is a lot, like thousands of cu ft, a compressor makes sense.