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[Jon Wehrenberg]

John,

Welcome to the asylum. It is already clear we will be asking you questions, but unlike the standards we subscribe to, you will have to provide correct answers.

Actually you have likely noticed this site has a considerable body of collected knowledge and while we may not always be correct we try.

One question......since energy is energy is energy have you considered your DC powered AC unit will put a bigger load on the batteries and as such may compromise your use of shore power or battery power when not connected? I like to think I am creative and from time to time I even believe I can improve the wheel, but the reality is these coaches have evolved over time and the converters have really taken all the factors into consideration and come up with the best compromise. I'm not saying our coaches cannot be improved, it is just that there are many good reasons why they are designed and built as they are. Your roof airs for example are cheap, readily available, and the generator running them literally sips fuel.

[Jeff Bayley]

John-

I have the same year Royale as you and build number 193 or 7 units off from your you unit number 199.

I suspect even with the added efficiency of your design it is unlikely the batteries will make it through the night ; assuming that is one of the goals. You could use a smaller generator than what I proposed in the rest of this message that I'm PM'ing you if all you wanted to do was keep the batteries up but you’ll have a fuel tank capacity shortage unless you put a feeder tank (Marine style) Easier to just use the aux generator by that time but I'm getting ahead of myself. I presume that your goal is to A/C the bedroom while boon docking w/o use of the big on board generator. With my method you can run any one high draw appliance (water heater, washer or dryer, stove, etc) at one time and pick between zones of the A/C’s rather than being restricted to the one DC air conditioner in the bedroom.

RV parks are not my bag for various reasons. Cost is not one of them but it is cheaper for us and our particular style of traveling. We would rather pick our own view and boon dock. We have never made a reservation at an RV park in 8 to 9 years since I bought my first RV (this coach).

I did a LOT of trial and error before coming up with this solution which I am very happy with and is working great (for me and my needs). I have a large collection of different size generators to show for it but I've got other uses for them also. I have other buses for one thing including a second Prevost. I wonder why I'm broke?

While you and I both wait for your DC air (sounds up my alley) here is what will get you by in the meantime if you have your reasons (as I do) for not wanting to run the generator. My reason is paranoid of fire since the turbo burned up on my one time and almost caught fire but I was lucky and caught it before it flashed from all the oil spitting on the hot engine. So I can’t get a sound nights sleep with the onboard generator on. With the portable one OUTSIDE my bus I sleep like a baby. You can use a braided flexable lock to secure the generator to the front bumper.

I use the onboard diesel generator during the day usually and just use the portable one to make it through the night. As Jon brought out, our on board big ones are very fuel efficient use the same amount of fuel as the small gas ones so there is no savings in fuel nor is that my goal. My purpose is to boon dock, have one rear A/C (or heater if you not using the Aqua Hot), and not to worry about waking up to the bus on fire. If we are at some event (like the Oshkosh are show) and want to come back to a cool bus then I will leave that portable unit on and enjoy myself much better while away from the coach not having to worry about an unattended onboard generator catching fire.

I’ll PM you the long detail (did he just suggest this one was NOT long ?) on which generators are ideal for this considering price, fuel tank capacity, compact and low noise. If anyone else wants a copy of what I’m sending John, email me (I drift in and out of POG) and I’ll gladly send it to you. Too many others are disinterested in this and my messages are long and detailed. This is my short posting ! As I said I drift in and out in spurts and my poor fellow POG'ers are subjected to this (are you still reading guys ?).

Jack wrote: “Welcome John, It sounds like that you could design an AC unit but wouldn't it be easier to add an inverter for the rear AC unit or maybe just rewire the existing inverter to run the rear AC ?”

>>>> I rewired my House side panel and my Shore Power / Generator side panel with a toggle switch to do just that and I haven’t had to let the smoke out yet. I can run my roof A/C’s while driving if I wish to and it works good but forget about running an A/C off the batteries for more than 10 minutes before it kills the batteries. I have a 275 amp alternator that puts back what the A/C’s are taking for the roof airs when I’m truck’in.

I’m PM’ing you the rest. Sorry for the thread creep Donnie but John started it. I’m looking up where your located to stop at your place and get some free help with other issues. Just kidding about the free part. Wait, you don't have a profile. I think your in Florida maybe. Let me know so I can come pester you.

[johnklopp]

Wow, its going to be great getting to know you guys and collecting some of your compiled Prevost knowledge. Guess I started out wrong and took this thread in a different direction and I apologies for that. I should have started a new thread but I'm learning so I will try not to do it again.

I agree that the power management on the coaches is very well set up and is probably similar between converters. The thing that has changed is the availability of dependable brusshless DC motors. The best example would be to look at a hybred car. The Prius has a DC drive train and air conditioning compressor allowing the engine to be switched off some of the time. One of the advantages of a brusshless DC motor is that it can be easily speed controlled to match the load rather than turn of and on. My occupation has me designing DC air conditioning systems for the military to allow our troops to have a silent watch with low noise and heat signature to avoid detection by the bad guys. Almost every US military vehicle has DC powered air conditioning systems cooling the electronic loads.

It would be difficult to say that this is a cost effective approach at this time but is is more efficient. Brusshless DC motors are clearly in the future for many mobile applications. As an engineer, life is an equation and one of the factors is entertainment. This is entertaining for me.

[Jon Wehrenberg]

Even if you were able to double the efficiency of a 13,000 BTU AC unit and reduce the draw on batteries the available number of amp hours in a typical coach may increase your ability to run the AC from 1 1/2 to 3 hours at which point the batteries need to be charged.

Almost everybody (not an exageration) seems reluctant to run the generator. Those things will give tens of thousands of hours of service. It is not uncommon to see them exceed 30,000 hours of life. Under the load of the average coach with 2 AC units on all the time the fuel used is likely to be less than .5 GPH. We drag that generator around with us where ever we go and none of us really works one as hard or often as we should to get the life out of them. They are oversized such that we cannot overload one.

If you run AC units from DC power, you still have to replace the power consumed. If that means running the bus engine or a generator you still use fuel. If you have shore power available for recharging, why not just use shore power for the AC?

I am not being critical of your aspirations, but would like to engage in a serious discussion about the merits of your concept. One weakness right now with most conversions is the house AC units do need the generator to be running unless the inverters are set up to run the AC units. In that case power is used to run the AC units and the batteries may need a charge when connected to shore power. If that is the case that is shore power not available for something else. A low current draw DC unit will be an idea embraced by the entire RV industry, but it truly needs to be a low current draw. AC or DC energy is energy is energy.

Don't worry about thread creep. This site is known for the inmates of this asylum being incapable of keeping on point. It's kind of like we get ideas and they just fall out of our brain onto the post.

[Will Garner]

Jon,

As you know the very day I needed my generator that I have been dragging around (and using) for the past four years it quit on me. Also as you know it turned out not to be a problem with the generator but with the alternator used to charge the generator battery and supply sufficient electrical power to keep the diesel running. Funny, I had the generator serviced before leaving on the Maine trip so I was confident I would not have a problem. I run the generator when in my electricity-less but free storage building doing projects. Yes the building has plenty of ventilation - you can see holes in every wall and some in the roof. I also leave the doors open. Works for me. On my coach what I found was the commutator surface had been compromised, read destroyed, by one of the two brushes and in the process that brush broke off when it made it to the harder base metal. The good news was we found the source of the problem. The alternator was not putting out enough charge to keep the battery up and while at lunch it quit. The bad news was the alternator on my generator is no longer in production. There was one with 65 amp output vs. my puny little 37 amp unit but it could not be delivered to the Rockland ME NAPA store for three days. Big schedule impact. NAPA did hook me up with a local generator/starter/alternator rebuild shop. I dropped the alternator off at 4:45 PM and it was ready by 10:00 AM the next day. The coach generator is now very happy. Now if only it would fail when it was being run in the garage!

Exercise is the answer to living a long life.