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Topic: On board air compressor - now 12v vs 120v (Read 12 times) previous topic - next topic
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On board air compressor - now 12v vs 120v
Yahoo Message Number: 148967
First, this is a personal opinion with little experience with 12v compressor units.  Weigh it accordingly.
 Think in terms of energy needed.  It takes the same amount of energy to fill a tire using 12v as 120v systems, assuming friction losses are the same.  However, it takes 10 times as much amperage at 12 volts to provide that energy as with a 120 volt system.  That increased current means much larger wires are needed to carry the needed current.  Heavier wire is needed in the motor coils, thus more heat.  More load is on the motor brushes, increasing the risk of burnt brushes.  The increase in copper adds to cost and weight, assuming equal energy needs.
 There is one downside to a 120v system that I can see.  If I am not plugged into shore power, I need to run my generator to use it, and that means a heavier carbon impact.
 Viewing it as an engineer, assuming I have the option, there is no way I would choose a 12v motor over a 120v motor for long run, heavy load functions such as running a compressor.

Ken F in NM
'08 MB
Re: On board air compressor - now 12v vs 120v
Reply #1 –
Yahoo Message Number: 148973
"Viewing it as an engineer, assuming I have the option, there is no way I would choose a 12v motor over a 120v motor for long run, heavy load functions such as running a compressor."

Ken

From an engineering point of view you are right, if long term durability is your goal.
If the 12-volt motor was being use often, I would agree but with good tires, adding air to the LD's tires, in the field, isn't something we do often, if ever. And 12-VDC motors can be very durable and powerful, our V10 starter motors are a good example.

Problem I have with most, if not all, 120-VAC compressors is their size and weight. Lugging a big, 40-lb compressor around on the off hand chance that air is so badly that it can't wait until we get to a service station safely is too much for my small rig.
With a TPMS, this shouldn't happen often, usually only if the tire has a leak. With a monitor, you can see when a tire is down a couple pounds, allowing you to safely wait to add air until the next time you refuel.
Now, if someone made a decent, reasonably priced small 120-VAC compressor, the size of some 12-VDC models, I would be interested. The 12-VDC compressor isn't very big and there are other important things to occupy our 23.5's limited storage space. YMMV
 There are excellent 12-VDC compressors that will inflate RV tires.  Both VIAIR and ARB sell high-end 12-VDC compressors that are used throughout the off-road community.
I have been carrying a compressor in our two LDs for twenty years and have never needed it to inflate one of our tires. It has been used to inflate bicycle tires, the Jeep tires, basketballs and a few friend's low LD tires.
To keep everything electrically happy, a 10-gauge extension cord is used with the compressor.

When it comes to needing air, the Jeep is another story. The BFG AT tires lose air much faster than the LD and the tires also get significantly aired down when we off-road. This is why the CO2 tank is carried. It can produce volume and pressure to vastly exceed any portable 120-VAC compressor that will fit in one of our storage bins. With the Jeep also equipped with a TPMS, I know when to top the tire pressure during refueling.
Other member here have used CO2 systems as their on the road inflators. a 5-lb tank would be more than adequate.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: On board air compressor - now 12v vs 120v
Reply #2 –
Yahoo Message Number: 148975
If you don't need a compressor but just a tire inflator consider this option: Husky 120-Volt Inflator-HY120 at The Home Depot

I have been using this for over 2 years with no problems. I connect it to city power if available, otherwise run extension cord to generator outlet. Weighs maybe 5 pounds and dimensions are small.

Bob 01 23.5 TK with toys
Re: On board air compressor - now 12v vs 120v
Reply #3 –
Yahoo Message Number: 148984
I am one of those people that hauls around a 120 volt compressor and in 12 years it has been used 3 times. (Once because my TPMS showed a tire very low and I was in the middle of "nowhere.")  My current compressor is a Campbell-Hausfeld unit with a  2 gallon tank and maximum pressure of 110psi.  The "restart pressure" for the unit is 75psi.  To fill 80 psi you must stop filling when the tank pressure gets down close to 80 psi, bleed the tank down to 75 psi to restart the compressor, and wait until the tank pressure gets to 110 psi and the compressor stops.  It takes 3 or 4 of these operations to raise the tire pressure a couple of pounds.  It is also pretty noisy and I hate to run it in campgrounds.  All things considered, particularly the infrequent use, I am thinking about replacing it with a quality 12 volt inflator of some type.  The inflator should weigh less and take less space in the storage compartment.  Hopefully it will also be more quiet.

Doug Baker
Re: On board air compressor - now 12v vs 120v
Reply #4 –
Yahoo Message Number: 148986
My current compressor is a Campbell-Hausfeld unit with a  2 gallon tank and maximum pressure of 110psi.  The "restart pressure" for the unit is 75psi.  To fill 80 psi you must stop filling when the tank pressure gets down close to 80 psi, bleed the tank down to 75 psi to restart the compressor, and wait until the tank pressure gets to 110 psi and the compressor stops.  It takes 3 or 4 of these operations to raise the tire pressure a couple of pounds.  It is also pretty noisy and I hate to run it in campgrounds.

---- Doug, I think we have essentially the same compressor, but yours is a lot newer. (Mine is an eleven-year-old CH FP2003; the newer ones are labeled FP2040 or FP 2840, I think.)

Yes, the compressor has its drawbacks of being slow, heavy, somewhat awkward to lift in and out of the compartment, and it's a bit noisy, but the thing has always worked reliably and the straight foot inline chuck I put on the pigtail hose allows me to get a grip! I detest those little cheeseball valve connectors on 12V inflators, but it seems they work for some people.

If possible, I'd try to someone who has a 12V inflator of a brand you might be interested in and do a test run to see if it would work for you. ???

Joan
2003 TK has a new home
Re: On board air compressor - now 12v vs 120v
Reply #5 –
Yahoo Message Number: 149018
VIAIR Corporation - 450P-Automatic Compressor (P/N 45043)

These units come with the air guns that have a decent gauge built in with trigger operation and the valve stem clamp.  Nice carrying bag holds everything.  13 pounds.  They also market a 440P-RV model to the RV community that is this compressor with an additional 35 foot hose and an extended-reach chuck for rear tires.

Dan
2007 IB-30
 
Re: On board air compressor - now 12v vs 120v
Reply #6 –
Yahoo Message Number: 149019
VIAIR Corporation - 450P-Automatic Compressor (P/N 45043)

VIAIR Corporation - 450P-Automatic Compressor (P/N 45043) Specifications  Performance Data Fill Rates - 12-Volt - Permanent Magnetic Motor - Duty  Cycle: 100% @ 100 PSI - Max. Working Pressure: 150 PSI - Max. Amp Draw:  23 Amps

View on www.viaircorp.com

right

These  units come with the air guns that have a decent gauge built in with  trigger operation and the valve stem clamp.  Nice carrying bag holds  everything.  13 pounds.  They also market a 440P-RV model to the RV  community that is this compressor with an additional 35 foot hose and an  extended-reach chuck for rear tires.


 Is the Viair worth the extra money. Cost $270.00. And keep in mind that it is something that you may never use.
I Got this 110 volt compressor from Harbor freight for $40.   http://www.harborfreight.com/3-gal-13-hp-100-psi-oilless-hotdog-air-compressor-69269.html       The foot print is about the same. I have carried it for 2 years and not used it yet

The HF unit puts out 1CFM at 40 PSI.
Viair puts out 1.31 CFM at 40 PSI but that is with 13.8 volts. You will be lucky to keep 12 volt even with the MH engine running. You will need to run the MH engine since the unit pulls 23 amps. That will put the CFM below 1 CFM. The HF 110 will not drop in CFM because it is 110 volt The HF unit will need the generator running but it will use less gas.

George

Retired plumber