alternative to generator February 20, 2003, 11:05:16 am Yahoo Message Number: 19152Hello Gang,They say necessity is the mother of invention. Well, not having a big pot of money laying around or an endless supply of CCC has led me to look for alternative ideas. I started thinking about what I really needed a generator for and the pro's and cons of having one. The biggest cons are, I really only need it when I go on long trips in the summer time, but yet, I have to carry 200 lbs of stuff I don't need all of the time. Because cargo weight is something I really have to monitor, it makes a huge impact on CCC. So I started looking into portable a/c units. I figured I could find one that could keep the cabin temps bearable but yet not need a humongous inverter. Below are a couple I found that seem to fit the bill. The second one listed is a conventional type a/c unit, the first is something quite different. It's cooling capacity seems rather small, but if I isolate an area it may work. For example, put it either in the back lounge area and close the curtain door or put up front and open the bathroom door to close off the back area. The second option may be more effective because it would supplement the cab a/c. So opinions anyone? I'd like to hear your thoughts on using a portable a/c unit and the units below. I'm not set on going this route, but just want feedback on it's viability. http://www.kooleraire.com/Home.htm http://www.spotfree.net/aircon.htmlThanks,-Victor 91 26.5 MB
Re: alternative to generator Reply #1 – February 20, 2003, 11:25:35 am Yahoo Message Number: 19156VictorWe had the same problem in our '83 LD. The poor passengers in the rear of the coach cooked during summer travel. This is the major reason we wanted a generator so I understand your needs. I wonder if the kooleraire has the cooling capacity to make much of a difference a 26.6' LD. Where are you planning to get enough ice to keep it stocked? If it actually blows enough cold air, it will go through ice quickly. The spotfree will still require a 120VAC electrical connection to power. So you will still need a generator to power it. The engine`s alternator, combined with a large (expensive) inverter is not large enough to power it.I really do not see an alternative to having a genset for powering the rooftop A/C.Larry
Re: alternative to generator Reply #2 – February 20, 2003, 12:06:10 pm Yahoo Message Number: 19158Larry, I thought about the ice issue too. Figuring if the ice would last as long as a tank of gas, I could restock at a gas station. Trying to go with block ice if possible, it would last much longer.The smaller Spotfree unit runs at 800 watts, that doesn't seem to much for a decent inverter to handle. Or am I missing something?Thanks for the comments,-Victor
Re: alternative to generator Reply #3 – February 20, 2003, 12:45:40 pm Yahoo Message Number: 19160--- Quotesupplement the cab a/c. So opinions anyone? I'd like to hear your thoughts on using a portable a/c unit and the units below. I'm not set on going thisQuoteroute, but just want feedback on it's viability. http://www.kooleraire.com/Home.htm http://www.spotfree.net/aircon.htmlThanks,-Victor 91 26.5 MB Victor, I think the unit that uses the ice in the cooler would be totally unsatisfactory. To put it in perspective the factory installed roof ac is rated at 13500 btu per hr. This is equal to the cooling affect of melting about 94 lbs of ice per hr or about 11 gallons frozen water. It appears that the second unit may have only an exhaust for getting rid of the hot air removed from the space. If that is the case then the air for the exhaust will be removed from the conditioned space. This will cause warm outside air to be pulled into the space as the hot air is exhausted. That air will then need to be cooled. The factory unit does not require any of the conditioned air to be exhausted to the outside for the unit to operate properly. In other words the factory unit will be more energy efficient. Also, if you are planning on running the unit on an inverter I think the weight of the inverter and the extra batteries you will need will weigh more than the generator.Norm
Re: alternative to generator Reply #4 – February 20, 2003, 02:02:38 pm Yahoo Message Number: 19165"The smaller Spotfree unit runs at 800 watts, that doesn't seem to much for a decent inverter to handle. Or am I missing something"VictorA/C unit require at least twice the run wattage for starting. This probably would require a 1500-2000 watt inverter. The Spotfree draws 890 watts. Allowing some power loss in the inverter and wiring, this is atleast an 80-amp load on the alternator. Your Ford has, I think, a 130-amp alternator. Automotive alternators only provide full output when cold. The output drops off considerably as it warms up. Your alternator may not have more than 100 amp capacity after warm up on a warm day. This is not enough to handle the load of the engine and the inverter especially since you will also be operating the dash air, which uses a bit of power for the compressor clutch and the fan. Even if it would provide that much power, it would require continuous full output, which will lead to its early failure. The installation of a larger alternator and wiring could be done but once again is a very expensive alternative. I still thing a genset is the best way for to go if you can figure out how to keep from overloading the chassis.Larry
Re: alternative to generator Reply #5 – February 20, 2003, 02:14:54 pm Yahoo Message Number: 19166My two cents' worth: 1 cent: The Kooleraire is a joke. Don't waste your money. I doubt it could cool your shower stall, let alone the rear of the coach. 2 cents: As has been pointed out, the Liberty Design portable 8,000 BTU unit draws almost a thousand watts. Yes, you can get a 1,000W inverter (actually, you'd probably need more than that to handle the A/C compressor's heavy startup draw), but inverters don't manufacturer power--they merely take it from your batteries and change it to another form. So the real question is: how much power do your batteries store? LD's standard batteries give you 220 ampere-hours of capacity. At 12V, that's 2,640 watt-hours. Since an inverter is only about 90% efficient, let's say 2,500 watt- hours. So...if you drain your batteries completely (which will ruin them), you can run that portable A/C unit for a little less than two and a half hours. If you only drain them halfway (the maximum recommended), you can run the A/C for a little over an hour. I think you get the picture. Battery-powered air conditioning isn't practical. The fundamental fact to remember is that almost anything involving heat--either generating it or moving it around, as with an air conditioner--takes massive amounts of electricity. You can't get nearly enough juice from batteries--even LD's optional heavy-duty batteries--even Gertie's FOUR heavy-duty batteries!--to run a meaningful air conditioner for a meaningful length of time. If you must have A/C, you need a generator or shore power. And if you're going to use an air conditioner, you might as well use the one on the roof. It'll do a much better job than that underpowered roll-away portable, and you won't have to cut a hole in the wall for the vent tube.Andy Baird :-)
Re: alternative to generator Reply #6 – February 20, 2003, 02:21:32 pm Yahoo Message Number: 19168QuoteLarry,I thought about the ice issue too. Figuring if the ice would last as long as a tank of gas, I could restock at a gas station. Trying to go with block ice if possible, it would last much longer.The smaller Spotfree unit runs at 800 watts, that doesn't seem to much for a decent inverter to handle. Or am I missing something? In the ad for the air conditioner it tells you the power to size a UPS - this would be similar for an inverter, which is what is built into a UPS. The air conditoner is sized small, and likely not designed for the amount of airflow a roof air unit produces. It will need 18"X17" of floor space - a lot!, and needs venting out an open window - a pain. Insulation even in a LD is no match for a house, so 8000 btu's may not keep up on the worst days.You can get and plumb in swamp coolers for a vent location, if your LD does not already have one. The temperature may not be quite as cold as ice will produce, but the improved efficiency of design likely will give better results - without a big cooler sitting in the middle of the floor. It will also work without needing icemaker access - just water in your tank. They don't do well while the vehicle is in motion, though - a consideration. Either design will load your dash air a lot, due to increased humidity.Steve
Re: alternative to generator Reply #7 – February 20, 2003, 02:42:07 pm Yahoo Message Number: 19178Victor,Of the two devices the KoolerAire would be the better of them. It won't cool down the back that much but it will send cooler air circulating than just a standard fan and the kids could have some cool drinks in the cooler close by as well to help keep them cooled off. The portable A/C unit even at 890w of AC would still draw over 80 amps of 12vDC on an inverter and that's assuming you get the "optimum" efficiency from the inverter running it. That rarely ever happens believe me! The inverter companies would like you to believe that's the average but if you really read their specs it clearly says "optimal" efficiency not "typical" or "average". Even today's higher efficiency inverters typically get about 80% overall, of course it depends on the type of device being powered and the load it draws. It would more likely draw closer to 90 amps and you would also be running the dash air and other items like maybe the radio or TV or both and charging the house batteries or other things so it could put a big strain on your alternator to run one.Those portable units do a decent job of cooling an area but do need to vent to the outside to send the heat they extract from the area being cooled out of that area. That means gettingI've found that with the shades down on the side the sun shines through the windows and running the dash air along with 2 12vDC fans keeps the entire coach comfortable enough. I have one clip to the center of cab on the cabover bed overhang in the folded/stored position. We keep all dash vents pointed up and the center ones positioned straight back but in the upward position. This fan blows the cool air to the back better. The second one is in the back low blowing forward or toward the passengers but in a forward direction to help improve the convectional flow of air. If that doesn't work for you then you could try 2 in the back or a total of 4 (2 in the cab blowing back and 2 in the rear blowing forward). This would still draw far less current. If your dash A/C is working correctly even in very hot weather that should keep the entire rig cool enough to be comfortable. That is provided you don't have the sun shining in through the windows to help raise the temp even more. Even if you close the shades 3/4 of the way it helps a great deal and you don't have to readjust as often due to turns and the changing sun angle. I've also found that if the coach is pre-cooled just the 2 fans work fine even with our dash A/C not on the coldest setting or the highest fan speed. Even when starting out with a hot interior if we vent as much as possible with the vents, windows, and doors open and Fantastic fan on first then closing everything except leaving the FF going along with the 2 additional clamp-on auto type the rear gets comfortable within an hour or so. We then turn-off the FF and close that vent but leave the other fans blowing and it's fine. Of course we do live in Fl so we are more used to hotter weather especially in the summer. If it's anywhere between 75-80 degrees it's comfortable to us when we're wearing few clothes and not in the direct sun. Even more so when there is a cool breeze blowing or a fan moving the air aroound you or blowing directly on you.Do you have any insulation in the roof vents when traveling? What about insulation on the above floor level storage compartment doors? These areas should be addressed to help with cooling or winter heating because a lot of heat/cold comes in via them. The generator would be the best option if these things don't work for you but you should try them first. Most RVers rarely use a generator once they have one and it's a lot of extra weight for as little as they are used when you don't have a lot of CCC to start with. Your rig is one the E350 so that is a major concern for a 26.5 motor home especially with 4 or more traveling.
Re: alternative to generator Reply #8 – February 20, 2003, 04:04:33 pm Yahoo Message Number: 19182Thanks guys for clearing up what was unclear to me. I now see the light. I think I will take Mike's suggestion on insulating the coach better and getting my cab a/c checked out to make sure it's okay. The idea about the fans is something I had already thought of, but I see I can always go with more fans.Thanks again guys.-Victorp.s. - I love this list. It helps me look smarter to my wife. :-)
Re: alternative to generator Reply #9 – February 20, 2003, 10:02:38 pm Yahoo Message Number: 19195Victor- Your best choice for a small A/C would be the Coleman Mini Mach Roof Airconditioner http://rvcomfort.com/RVP_pdf/mini_US.pdfIt's 7100 BTU and nominally draws 8.2 Amps. It's much more efficient than the ones you cite because the roof venting carries away more heat than the vent tube.However, I don't think that's enough cooling for your LD. And
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