Different Wisdom

Discussions about all things to do with buses, trucks, and the homes made within them.

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Lostranger
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Re: Different Wisdom

Post by Lostranger »

Sorry I can't contribute anything to the giant breaded prawn inquiry — would love to know more about that, by the way — but I have to talk about my latest bus epiphany. Just yesterday, nice folks on busconversions.com made me aware of a marvelous device called the APU. I'm certain that the rest of you already knew about that, but apparently I lead a sheltered existence. The down side of my new awareness is that now I have to own an Auxiliary Power Unit. At the risk of boring the rest of you, I'm going to recount the marvels of this treasure for my own benefit.

Dating back at least as far as WWII, APUs are found in every jet plane and in many military vehicles. The proliferation of anti-idling laws prompted their adoption by the trucking industry. A typical APU for an OTR truck consists of a small diesel engine (often 2 cylinder, around 12 hp, Kubota and Perkins seem popular, but other brands in the mix), a high capacity alternator (output might be 12 or 28v dc or 110v ac), an air conditioning compressor and a heat exchanger. I found a few with hydraulic pumps instead of AC.

Compact package mounted on the truck chassis. Usually the AC compressor and the APU engine coolant are routed to blower coils in the sleeper. Sometimes AC and electric are routed to a reefer box or trailer. Sometimes APU coolant is routed through the trucks cooling system. That way, the main engine is warm when the driver awakes.

Bottom line for me is that, after doing all that work refurbing my Kohler 4500 watt generator, now I'm not even gonna use it. Before another winter hits this part of the world, I will have an APU in my bus. As an old friend and dairy farmer used to say, "Even if I have to sell a cow." (I don't actually have a cow to sell, but maybe I could steal one.)

Apparently these things are available used in the "well under a grand" category. I think I can get more than that for my Kohler. An APU in this price range would likely need work, but I'm not afraid of a project.

Here's what I have in mind: Reading Rob Gray's build thread in 2010 is what convinced me that a bus for full timers can operate on a solar budget. Even he, however, has a small backup generator. (And recently bought a much larger generator to use at the home place.) In that thought process, I gave up the idea of two large roof air units and an 8K diesel generator. We lived through the last two summers with just fans, but it was not always pleasant.

Since we got the Gillig, I've been planning to cut a hole high in the rear bulkhead and mount the smallest room AC unit I can find above our bed. With the rear of the bus well insulated and shut off from the main living area, I believe we could cool bedroom/bath/laundry area with such a small unit AND not have to run a generator to do it. As of now, I'm still planning to do exactly that, BUT, now I'm also planning to put an APU where the generator was going to sit.

I'll mount a blower coil in the bedroom and maybe a small radiator on each side of the bed. That way we can be warm or cool with only that tiny diesel running AND charge the batteries at the same time. While I'm at it, I'll probably run lines to the AC blower in the dash and include selector valves in the system. We could have cabin AC when we're traveling without having to add another compressor to the prime mover. No, I'm not thinking of getting rid of the wood stove, but an APU will make a far better backup heating system than would radiant propane heaters. What's more, not using my generator will mean that I don't have to carry gasoline — petrol to the rest of the world. I like that idea.

Words cannot express my excitement at this development. Starting today, the hunt is on.

Here are a few shots of the generator with my homemade exhaust manifold in place:

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And have you seen my '85 square body? Scottsdale trim, 4x4, 3/4 ton. I like it:

Image
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stuartcnz
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Re: Different Wisdom

Post by stuartcnz »

Whilst I have had an awareness of APU's, that awareness certainly lacked the clarity that you have just added. Which does shed a different light on them to what I had. I was also of the impression that they were very expensive, which could also be why I had never looked more closely at them (They are not used in trucks over here). Even for a diesel engine of that size (very handy size for many boats), it looks like it could be a more affordable way of obtaining one.

Where are some places on-line to look at second hand APU's?
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Re: Different Wisdom

Post by Lostranger »

Stuart,

Check this link: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... NA:US:1120

Inadequate description says it is not working but no details. I've written the folks and as yet have no reply. From the looks of it, I'd say it has to be fixable. I've just begun my research, but I agree that this is the way to obtain a small diesel. What's more, I need to build a small walk in cooler for our organic vegetable business. I believe a second APU will find it's way into that setup. We've also decided that we want to finish our house truck after the bus is better in hand. The truck would make great intern housing, guest housing, and short term traveling platform. An APU would be IDEAL for that. The possibilities are literally endless.

I will keep you posted.

Jim in NC
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Re: Different Wisdom

Post by Graynomad »

Noticed you are in Gin Gin right now
Yep, we've dropped anchor for a while on our land.
something fried with a couple of small bowls of other stuff...would you have any idea what they might have that looks kind of like a breaded lobster without claws
I can't really tell but I suspect that is just a piece of battered fish that by chance has taken on the look of something else.
so was wondering if you have ever eaten there?
'Fraid not, I haven't eaten out for decades.
would Gin Gin be a place to add to the visit list if we ever make our way south? (Likely a long time from now....)
Apart from me there's not a lot to see around Gin Gin :) It is however on the main highway so it's on the way to all the stuff people normally want to visit in Queensland. If you want to try a spot of camping in the Oz bush, watch the wallabies and shoot the shit around a campfire feel free to drop into our place if you get down here.

EDIT: Same offer applies to any other busnuts and motorhomers visiting Oz BTW.
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Re: Different Wisdom

Post by Graynomad »

The truck would make great intern housing, guest housing, and short term traveling platform.
I've been thinking similar about Wothahellizat, if we move into the containers (and that's the plan) it could be used for guest accommodation, even a B&B although there are legal issues with that.
intern housing
What are you teaching to interns?
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Re: Different Wisdom

Post by Lostranger »

We grow organic vegetables for market. Our first ever intern is living in the house truck now. She's a rising senior at Warren Wilson College and is majoring in sustainable agriculture. It's working so well that we're planning to continue. We may be able to arrange with WWC for interns to get course credit. I understand that Samantha will at least get community service credit for this summer. We're 1/2 hour from the college, and we're gonna offer free housing during the school term if someone is interested in commuting from here. We're building a second greenhouse, and we'll have some gardening work year round.
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Re: Different Wisdom

Post by Lostranger »

[quote="Graynomad"]Wothahellizat... could be used for guest accommodation, even a B&B although there are legal issues with that. [quote]

I'm constantly surprised by the things governments stick their fingers into. Guess I shouldn't be. We have the best politicians money can buy. Sounds like you have more of the same.
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Re: Different Wisdom

Post by Graynomad »

Sounds interesting. I know nothing about growing stuff but I plan to learn a bit because we are going to stay here for some time and I'm setting up the property so we can be reasonably independent of the system. So far that means more technical stuff like a house and solar power etc, but food production is on the list as well.

Yes I'm sure our politicians are cast in the same mold as yours, also there would be insurance issues for a B&B, you can bet someone would stub their toe on a log and sue me for all I've got (approx $38).
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Re: Different Wisdom

Post by Lostranger »

Big news! I have acquired an APU. The price was right in spite of it being 500 miles away in Central PA. Bev and I are going after it next week. It's a ThermoKing Tripac. I've been able to find out a little about it. If any of you know more, please post. It's a Yanmar 2 cylinder. Has alternator, AC compressor and coolant loop for preheating engine. Online install manual says to use it with a cab/sleeper mounted heater that burns diesel directly. I believe I'm getting the remote heater in the deal, but my plan is to use the engine preheat loop to feed a pair of small radiator/blower units in the bedroom. And old friend who does truck repair has it, and he thinks it needs something fixed. He could not remember. I should know next week. I believe I'm getting the control unit and the AC condenser coil with the package. I'd love to know HP and RPM for this unit, but my research has drawn a blank on both issues.

I'm excited about the APU development. Definitely plan to put evaporator units in bedroom and at dash. Will include routing valves to select between the two. I imagine that engine start is controlled by the AC thermostat, but I don't yet know that. With such a small engine, either way is fine. Batteries will charge whenever engine is running. I may even buy the Magnum automatic engine start module that works with my inverter.

Stuart, I'm seeing several of these, in addition to just the engines, on eBay. Would be worth your time to search. If you can buy on the cheap, might be worth shipping from US. Especially if you're in no hurry. You have me thinking of the possibility of buying a small boat. (Not likely, but I can dream.)

Jim in NC
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Re: Different Wisdom

Post by stuartcnz »

Good news Jim.

I have no particular plans to buy one, though that may change in time, but very good to know about them, and I will start to keep an eye out from time to time.

The type of boat those motors would be good for, are small keeler yachts. They would be to small for most motor boats, with the exception of some micro tugs, which they would also be good for.
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Re: Different Wisdom

Post by Lostranger »

We're leaving in the morning to drive to Pennsylvania and pick up our used ThermoKing Tripac APU. Here is a spec sheet for the unit:

http://www.thermoking.com/products/prod ... RL=&cat=10

We've allowed an extra day for the trip because I'm confident that some of the hardware is still in the wrecked truck. I actually have a choice of two identical units, and I don't want to be rushed in the selection and uninstallation process.

I'm still getting my head around how this machine will interface with other aspects of our conversion. Heat and AC are mostly straightforward, but I'll need to charge our 24v house battery bank (490 amp hour) from a 65 amp, 12v alternator. Not sure how I should go about that. I don't want to replace the 12v alternator with a 24v version because I will also have to charge the starting battery for the APU. Any hardware suggestions? I can think of several possible routes, but I'd like suggestions. Dennis, this should be up your alley. I've also posed this question on http://www.busconversions.com

I'll post some photos of harvesting the hardware. Might even get to video it running.

Best to all,

Jim
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Re: Different Wisdom

Post by ol trunt »

Hey Jim. At the risk of hijak'in here goes. You are/were a part of a discussion on another forum regarding "grounding". Since I don't completely agree with several of the responses you got and since I find lots of people on that forum seem to have all the answers and little of the science behind the answers I thought I'd contact you here--hope that's OK. Jack

As a kid of 8 or so, I learned a painful lesson about electrical grounds. While playing one summer evening with a 120 volt spot lamp out on the dew wet lawn, I discovered the weak spot in cloth covered wiring. I'm old and the spot lamp was even older--out of the 1930's :lol: . Long story short. The lamp was two wire and when I got my hand grip around the bare wires, I, in my shorts and bare feet on the wet grass became the perfect ground. I still remember the burst capillary beds in my legs and one arm from the experience.. A fuse finally blue in the house or I guess I wouldn't be telling this story. I'm now very careful about grounds. I read every article I find and I have come to the conclusion that ground needs to go back to its source. If you are using battery power, the ground needs to go back to the battery. If you are using a genny, the ground needs to go back to it only. If you are using shore power, the ground needs to go back to it only. I'm not talking about neutral or common--just ground.

Here are a couple of examples of potential problem areas. Lets say you ground your 120 v system to the chassis of your bus and are using shore power. Lets next say that there is an open ground at the shore power post and a short in the toaster you are using in your bus. This happenstance will produce a "hot skin" on your bus and when you step from the bus to the camp site you will become the best ground with the resulting electrocution. It is always best to check shore power to be sure it is properly wired.

Your onboard generator (120 v) will undoubtedly be grounded back to itself but should be checked. Another situation arrises when one uses a portable generator to power their bus. Many portables including most Honda's and Yamaha's have what is called a floating ground and require a ground rod of some sort to be connected to their ground terminal. When these gennys are used in a bus they need to either have an external ground rod or be grounded back to themselves within the bus. One way to do this is to connect the neutral output to the ground bar of the genny and the ground of the various recepticals in the bus to the same bar. When shifting from shore to genny to inverter it is required that the ground be shifted (and isolated)to the appropriate ground. I choose to make these changes manually but there are electronic devices that can do this for you. Gennys with a floating ground can result in a "hot skin" situation in the event of a short circuit if they do not ground back to themselves. Hope this makes some sense. Jack
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Re: Different Wisdom

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ol trunt wrote:Hey Jim. At the risk of hijak'in here goes. You are/were a part of a discussion on another forum regarding "grounding". Since I don't completely agree with several of the responses you got and since I find lots of people on that forum seem to have all the answers and little of the science behind the answers I thought I'd contact you here--hope that's OK. Jack
Jack, your input is always most welcome in any forum. I, too, prefer the tone of this board, but I still get lots of info on "that other" one. The knowledge base there is extensive, and most of the folks are extremely helpful. It does require some intelligent sorting, however.

The question about grounding came to my mind during a different discussion on the other forum where I asked about charging a 24v DC battery bank from a 12v source. The APU I recently acquired has a 12v alternator, and all of its systems are 12v. Our house system is 24v.

Some of the posters in that discussion suggested that I merely run a 12v lead to each of my 4 8D AGM house batteries. Others claimed that doing so would cause a short to ground if those batteries are grounded to the chassis since the bank is wired series/parallel to get 24v. The claim about shorting the batteries did not make sense to me, but my ignorance is wide and deep in this area. I also did not like the idea of running a 12v lead to each of the four batteries for charging. Some suggested powering an inverter with the 12v alternator output and using the inverter to power a 24v charger. That solution seems expensive and inelegant at best.

My thinking at this point is to add a 24v alternator to the APU and a single 8D AGM for the 12v system. Then we could meet our small 12v needs from that battery, it would also start the APU and the APU systems would power from the 12v alternator when the motor is running.

But back to grounds: You said that you manually switch your ground bonding system when going from generator to shore power and back. Could you describe for me the particulars of that setup. I will be grateful. Last I checked, building codes require neutral bonding in a main panel but forbid bonding in a sub panel. I've always assumed that a bus panel would be considered a sub when hooked to shore power. We seldom use shore power, but I want to be prepared for that option.

Jim

P.S. I've not done much with my APU. Broke my phone on my way out of town to get it, so no pics of that sweaty process. Hope to have something to report soon. We're chin deep in vegetable work now.

P.P.S. I still don't have my mind around the best system for hooking up my two house battery banks. Right now I'm leaning toward chassis grounding every voltage, but I'm still researching and pondering.
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Re: Different Wisdom

Post by stuartcnz »

This is where Sharkey's presence is sorely missed. Electricity is his thing.

That said it may be worth a look in the archives of the Alternative Power section of the forum. Particularly for topics posted in by either Sharkey or AccordGuy.

Also have a look here: http://www.housetrucks.org/electrics.html It is a series that Sharkey wrote on electrics some time back. This is a very good primer on the topic.
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Re: Different Wisdom

Post by ol trunt »

Hey Jim.

" Last I checked, building codes require neutral bonding in a main panel but forbid bonding in a sub panel. I've always assumed that a bus panel would be considered a sub when hooked to shore power. We seldom use shore power, but I want to be prepared for that option."

Yup, that is exactly right--that way errant electrons are forced to go back to Ma Edison as they should. That being agreed upon, it doesn't follow to chassis ground your shore power (or the genny power or inverter power either) as doing so breaks this tenent and allows shorted current to "chose" its own path--not good. On the other hand, grounding battery power through the chassis and body makes perfect sense.

I have two separate electrical systems for the house, a 12 volt system and a 120 volt system each with its own fuse box etc. Working backwards from my 120 volt distribution box I have a 30 amp pig tail with a male plug. I have three 30 amp female recepts wired to 1) shore, 2) genny and 3) inverter. This allows me to chose my power source by moving the male plug to the appropriate location. Each of the female recepts is wired directly to its power source be it shore or genny or inverter as are their respective grounds. This way I have the final say as to where the power is comming from and where any shorts are going. Even if I were to have shore, genny and inverter power going at the same time there would not be any cross over because I can only use one power source at a time depending on where I plug in. Each 120 volt receptical or switch is hard wired back to the ground lug in the distribution center and the ground lug of the distribution center is directly connected to the appropriate ground depending on which power source I chose. None of the 120 volt grounds connect to the bus body or chassis thereby eliminating the possibility of a hot skin condition. Oh, and the male plug from the pig tail is never hot unless it is pluged into one of the recepts. I would strongly advise against using the chassis or body as a ground link for your 120 volt system as it will lead to a hot skin condition. Also, you will want to verify that the ground lug in your distribution center is electrically isolated from the bus and the distribution center itself or all your precautions will be for nothing. Jack

This is a pic of my three female recepts each made hot from separate sources. I chose the recept I want to use and plug in knowing the grounding for that particular recept flows directly back to the source. I see that my pic cuts off the third recept on the right but you get the idea. Image

This pic seems to show all three recepts. The pig tail is pluged into shore power in this pic. Image
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