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CruiseAir run on Inverter ? MSW Trace ?
Hi folks,
Working on the CruiseAir analogue to digital conversion and learned some interesting things from the engineers at MicroAir.
First off they do make a retrofit kit to change the 3 knob CruiseAir control to a digital Intermittent system. Getting that and then….I learned about a new product – EasyStart soft start A/C compressor device that allows you to start a 13-15000BTU A/C unit ( split system or roof) on less than 20 amps initial load and then drop to the normal 10-15 amps continuous run depending on BTU rating…..
Normally the amp spike is as high as 75 amps when the compressor starts and most power sources like small generators or inverters can’t deal with that…they shut down.
So….with less than 20 amps soft start, it becomes feasible to start and run a 14,000 BTU CruiseAir off an inverter. Why do I want to do that ? Would like to use the Front Cruise Air A/C as a OTR air without starting the generator. The bus has a non operational dash air and the CC version of OTR air components are trash. The pipes and hoses are not worth replacing plus recharging the system is very expensive only toi find another leak in a few days.
The front CruiseAir is very powerful and cools the Salon and dash area very nicely. If more is needed, then the generator gets started and you have power for the other 2 CrusieAirs and much more.
The missing piece of the puzzle for me at this point is…..will a CruiseAir compressor and cooler fan run properly on a Modified Sine Wave inverter ? I happen to have a spare Magnum ME3112 – 3100W unit ( 26 amp continuous at 120V with 90 amp surge)
I heard that some 90’s and even 2000’s Prevost conversions have the ability to run 1 or 2 CrusieAirs on a pair of Inverters and they used the old 4000W Trace Xantrex Inverters. Back then, they were Modified Sine Wave (MSW) not Pure Sine Wave and I am told they worked fine….it that accurate ? Some say that normal motors and compressors do not like the MSW but if it worked with a Trace MSW, then it should be ok, right ?
I will have 6 8D AGM batteries. Will install this dedicated second inverter just for the purpose to run the front CruiseAir. This CruiseAir will be modifed with the SoftStart device and Digital controls. The 12v alternator on the 8v92 engine is 250 or 300 amps – should compensate plenty the amp loss while the Inveter is making 150 amps of 120V juice for the CruiseAir…..I think I can make all this work as long as the CruiseAir can run on a MSW Inverter….
Thoughts ? Any body that has first hand experience with MSW Inverters that had success or problems with A/C compressor running, please contact me. Thanks
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22 Replies
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I doubt you’ll be able to run a Cruiseair on that Magnum, a roof air would be doable.
Do do you need Lifelines or have you already bought something?
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Did not get batteries yet.
If I can not do the CruiseAir on inverter I will get 4 8D’s, if it works I will get 6 8D’s.
Can you PM me prices please ? Thanks
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Maybe this is thread drift, but why is there an aversion to running the generator? The experts from Inverter Service make it very clear that running A/C units from an inverter is hard on the inverter.
I have never seen the starting load on my Cruiseairs exceed about 30-35 momentary amps.
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Marius, to answer one of your questions, my bus is set up to run 2 Cruisairs off the inverters, so yes, it can be done. I have two Trace 4k 24 volt inverters, two 100 amp equalizers and one 300 amp isolator running through six 8D batteries. This settup works fine without any “soft start” system. Even though I can run the Cruisairs through the inverters, I look at the syestem as an emergency backup in case my generator fails. For the reason Jon mentioned, I just run the generator if I need house air. As you know, I used to have a 1990 CC similar to yours. I always used the gen on that bus as well, but I’ll admit that the CC setup allowed some generator noise to enter the bus while driving with it running. If you are worried about wearing out the generator, don’t. Mine had over 51,000 hours on it when I sold and it still ran fine.
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Thank you. That helps a lot !!
I will do a trial with the Magnum as soon as the retrofit kits arrive before I tear into the Romex circuits to add the Inverter the proper way.
I am not afraid that I will wear out the Generator…just don’t believe in waste and if I can make something work with power already generated by the engine, why not ?
That Generator besides being noisy as you drive down the road, will eat 1-1.5 gal/hr. If you need whole house AC, makes sense to start it and let it do what it is intended for……but if all you need is comfort in the salon and Dash from one unit, if it can run on an Inverter with juice replenished by the alternator, to me it makes the best alternative to repairing the dash AC that is totally inoperable in this bus.
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Something to think about…
Your air conditioners run off AC current. Your diesel generator generates AC.
Your bus diesel engine runs the alternator that produces AC current that is converted (with some loss) to DC. The DC goes to the batteries and to the inverter that converts it back to AC (with some loss).
Either way, you are burning diesel to produce the AC current needed for air conditioning. The fewer number of times the power is converted, the greater the efficiency.
For me, I like to have the output of the big diesel to get the coach up the hill and not rob part of the output to go through several conversions to run air conditioning. The inverter experts tell us the large load that air conditioners put on the inverters will lead to problems. Inverter repairs are not cheap.
I can understand the noise issue of not running your generator but the economic penalty can be significant.
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Ditto what Les said. When it comes to physics, there is no such thing as a free lunch.
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Marius,
I agree with what has said by Jon Les and others. You will be building a system that will inevitably damage costly components like inverters batteries alternator and the air conditioner itself. You will be working that system to its maximum potential. It obviously can work but at what real savings. Your generator is the cheapest most efficient way to cool your bus with house air. It’s like picking up a big load of stone or sand in your 3/4 ton pickup because the pickup burns less fuel than your dump truck. You may save a little fuel but you may need a new trans or suspension. Just my opinion. Jeff
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In regards to what Les said, it’s true it takes the same amount of fuel to support the load of that air conditioner minus loss in the inverter scenario. The only gain would be that with the generator you,re running a 20hp power plant and only using 1 or 2 of those horses for the ac unit. The main engine feeding an inverter will only consume extra fuel required to support the additional ac load.
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I wonder what the efficiency of the 12/24 volt DC to 120 volt AC conversion is. There has to be some loss, as the inverters create heat.
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Magnum inverter will not run cruise air units….If it is hooked up the it will damage the inverter and/or the cruise air unit….
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Marius,
This is not theoretical but a dose of reality.
Your CC is a 12 volt house and likely has the 12 volt, 270 amp gear driven alternator. If you disregard the fact energy is energy is energy and decide to use the engine driven alternator as the power source for your A/C that is OK. You just have to understand the 50 DN alternator is what is producing the power and in addition to the normal loads it handles without the A/C, running an A/C on a 12 volt system through it adds a 130 amp load (not counting the starting load) through the alternator. The greater the load on the alternator the hotter it gets and the more it has to work.
There is nothing on your coach that has an easier job of handling the A/C loads than the generator, and there is no better way to enjoy all the features of your coach. If you get used to running the generator all the time you are using the coach you have all the A/C units available all the time so the bedroom is not a sauna when you get somewhere, you can be a complete energy hog anytime you want using hair dryers, the TVs, making coffee, running the microwave, etc. and you probably will be unaware of the small amount of fuel used.
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Your generator fuel consumption is about .5 gah.
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Well….I guess I got what I asked for.
This group and the wealth of knowledge is fantastic…..or to use correct terminology for these days ” Wonderful, Amazing, Bigly, Tremendous and so on”….
I will upgrade the CruisAir controls to digital and remote sensors and leave the system alone to run on shore and Generator. WIll rebuild the insulation of the Gen compartment, new muffler etc.
Thank you all. I agree with what was said. Now I have to work on the Generator where I have an electrical problem. Your expertise in this area will be needed. Will start a new thread in the Generator section.
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I just hope everyone realizes we make all these answers up.
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