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Old 07-10-2013, 04:32 PM   #41
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Re: Generator versus idling small diesel?

chromisdesigns: Thanks! Interesting. I wonder if AmplePower will use a smaller alternator pulley to increase alternator rpm, since the 7.3L diesel does not really like to operate much above 2000 rpm.

Chance: Are you good with the schizophrenic turn your thread has taken? I am still a proponent of you idling a 2014 Ford Transit 3.2L diesel for the times you need Air Conditioning. I really dislike the idea of having to duplicate systems on the house side which already exist on the van side. Big rigs have done this for decades. I don't see why you can't. But please post info on the carbon monoxide alarms and other safety devices you believe will protect you while sleeping.
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Old 07-10-2013, 06:09 PM   #42
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by E350
....cut.....

Chance: Are you good with the schizophrenic turn your thread has taken? I am still a proponent of you idling a 2014 Ford Transit 3.2L diesel for the times you need Air Conditioning. I really dislike the idea of having to duplicate systems on the house side which already exist on the van side. Big rigs have done this for decades. I don't see why you can't. But please post info on the carbon monoxide alarms and other safety devices you believe will protect you while sleeping.
Absolutely. Iím perfectly OK with any direction it takes. Many of the issues discussed have been great food for thought even when they were not directly addressing my initial questions of idling versus generators.

My primary goal remains figuring out the best way to occasionally provide air conditioning at night when shore power is not available. Initially I figured a generator or idling were the only real options that were reasonable and/or common-enough to ask about. However, the discussion of much higher capacity alternators (like yours) made me reconsider battery power; which I had considered for my present van many years ago. I have to admit being a little surprised about the many expressed concerns due to the noise and exhaust of ďbothĒ generators and idling. Regardless, itís all good to know.

The main reason I went with a low-capacity window A/C mounted inside my present van was because I wanted to be able to run it on a small inverter using batteries. And since I had estimated 5,000 BTU/hr was plenty for nighttime cooling, the low 600 to 660 watts (more or less) of required power made a lot of sense. However, now that my wife is retired we will be traveling much more often (including summers) and weíll need A/C during the day too, so much greater cooling capacity will be needed. A 5000 BTU/hr unit is probably not large enough for most vans no matter how small or well insulated if parked in the sun in a 100F day.
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Old 07-10-2013, 07:22 PM   #43
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by E350
chromisdesigns: Thanks! Interesting. I wonder if AmplePower will use a smaller alternator pulley to increase alternator rpm, since the 7.3L diesel does not really like to operate much above 2000 rpm.
I thought redline on those engines was close to 4000 rpm -- not that you'd ever want to run it that fast for very long...!

In any case, yes -- we had our Balmar on an old English Ford 4 cylinder slow-speed diesel, and then moved it to a Yanmar 4JH when we repowered, which had a redline around 3600 rpm. On the Ford, we sized the alternator pulley for about 120 amps at 600 rpm, on the Yanmar, we upped the size to give us the same output at about 850 rpm (IIRC, it's been a long time). In either case, it was intended to be a "fast idle" speed for that particular engine.

The key is to make sure you will never exceed max alternator rpm at the top end of your engine speed. Since these alternators can turn pretty fast, that's generally not a problem. Stock installs (as you already know) have the opposite problem; they don't turn the alternator anywhere near fast enough to give real power at fast idle speeds. You fix that with the pulley size.

Our install was v-belt driven, so we used duals to be conservative about belt loading; also that meant if we ever broke a belt, we were not completely out of commission until we could change it. With a timing-belt / serpentine belt drive, a single belt can handle more load.

You would want to consult the alternator vendor about pulley sizing, in any case.
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Old 07-10-2013, 09:25 PM   #44
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by Chance
I went with a low-capacity window A/C mounted inside my present van was because I wanted to be able to run it on a small inverter using batteries. And since I had estimated 5,000 BTU/hr was plenty for nighttime cooling, the low 600 to 660 watts (more or less) of required power made a lot of sense.
Do you have link or picture or make and model for this 600 to 660 watts low-capacity window AC? And maybe a picture of where and how you mounted it in your van? Very intriguing.
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Old 07-11-2013, 08:08 AM   #45
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by carringb
I see no reason to run a dedicated alternator for the house batts. I can't think of any advantage to that over a good isolation relay. FWIW the factory Ford aux battery setup won't charge the house batts until the starting battery has a full charge.
When running the Starcool or Danhard A/C, your house batteries are draining all day, even with the engine running. Add on top of this the fridge, lights and any other power draw items you have.

The stock alternator can't keep up, both because of its limited power and because of the nature of charge system.

Theoretically, adding a 250-300 amp second alternator, the house batteries would never take a big hit with the A/C on (or microwave) since the incoming power from the second alternator could exceed its requirements.

This also has the benefit of not over tasking the OEM alternator and keeping the systems separate for easier troubleshooting.

Of course, alternators cannot charge our house batteries much beyond 80-85% capacity anyway, since there is no smart controller for multiple stage charging. Does anybody know if any manufacturer has come out with a smart controller for battery charging from an alternator?
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Old 07-11-2013, 09:21 AM   #46
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by JoeyNick
Does anybody know if any manufacturer has come out with a smart controller for battery charging from an alternator?
Check out chromisdesign's link to Ample Power. Their alternators have a "smart" regulator which goes at least from absorption to float and has battery temperature compensation input and has an option of a remote LED monitor for the alternator and its output. Pretty friggin' cool!
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Old 07-11-2013, 02:50 PM   #47
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Re: Generator versus idling small diesel?

Hey Guys,

With reference to idling the 6.0 at low load for extended periods of time it is not something IMO that is idea.

My experience comes from working professionally as a yacht captain and yacht engineer from time to time, I sleep with a diesel generator running 250+ night per year.

We work very hard to avoid running the generators at low load. Anything less than 30% of rated output is a no no. It glazes the cylinder walls leading to premature oil burning and low compression and can cause wet stacking which cokes the turbo. http://en.wikipedia.org/wiki/Wet_stacking

With reference to super high output alternators IMO they are problematic as well. The horsepower required to turn a large alternator is more than you might think. A single belt driven system can only go so far. A dual belt system (we run them everyday) goes further but even these can be probalamatic. Belt dust, and bearing wear driven by high belt tension.

Last, obviously I feel very comfortable sleeping with diesel generators running. If properly maintained they are extremely safe! CO detectors make even poorly maintained units relatively safe.

Jim

2006 Quigley 21' 4x4 RV 5.4
2005 UJoint 6" 4x4 EB 6.0 PSD
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Old 07-11-2013, 06:25 PM   #48
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by E350
Do you have link or picture or make and model for this 600 to 660 watts low-capacity window AC? And maybe a picture of where and how you mounted it in your van? Very intriguing.
Itís a standard 5000 BTU/hr GE window unit I purchased at Home Depot or Lowes 7 years ago. The unit could have been rated at 5050 BTU/hr back them, not sure. I think I still have box in attic so if you need to know the model (although exact unit is probably no longer made today) I can look it up for you. It still works as when new and could probably be replaced for a little over $100. I selected the smallest unit I could buy so that the lock rotor current would be as low as possible. The LRA is 23 or 24 AMPS if memory serves me right. I wanted to be able to start directly from a mid-size inverter, and also for it to draw low operating current. Mine draws 5 to 6 AMPS depending in large part on outside temperature. When it first starts it draws less than 5 AMPS but then goes up as it operates for a few minutes which is normal.

Specs on similar but newer A/C units suggest they are even more efficient. I recently saw 5000 BTU/hr window A/Cs with energy efficiency ratings (EER) of up to 11. That would put their standard power draw in the range of 455 watts. As I understand it even an EER of 10 which is common today would only draw around 500 watts. Mine probably had an efficiency rating of about 8 or 9 back them. If powering from campground shore power then efficiency isnít all that important, but if trying to run on small generator or batteries Iíd recommend buying one with high EER if cost is not too high. Newer 5000 BTU/hr A/Cs are often rated below 5 AMPs.

I did a lot of bench testing with the A/C while designing the cabinet to vent to the outside (through the vanís floor), but itís probably more than youíd want to know. An important thing for you to know is that it doesnít meet the manufacturerís installation recommendation. I knew that when I bought it and was OK with taking the risk due to the very low cost of the A/C. The cabinet restricts air flow somewhat compared to what the A/C would see if installed in a window where the condenser is wide open on back. That slight air flow restriction can raise condensing temperature and pressure some, but based on my measurements I was satisfied that if the unit was factory rated to work at ambient temperatures up to 40 C, or 104 F, then it could work in temperatures up to 95 F or so without issues. So for night use itís well within its mechanical and thermal limits. And if I wanted to use it on extremely hot days, I can use a supplemental external blower to force more air over the condenser coil. But Iíve never needed to do so, not even when camping on the beach or Disney World in Orlando in summer. The unit has never tripped on high-pressure/high-temperature. Capacity is obviously limited but it works pretty well for its size.

Iíll see if I can figure out how to post personal pictures that are not being shared online. I took some pictures initially but mostly for documentation reasons Ė stuff that couldnít be seen later. And I canít seem to find them all after transferring them to a new computer. In any case, since itís a homemade conversion Iím not sure if itís appropriate to post pictures outside of that forum subsection. If so, Iíll just snap another picture.
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Old 07-11-2013, 07:39 PM   #49
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Re: Generator versus idling small diesel?

So what you're saying is that for $157.55, I could have shore-powered (and possibly, for short intervals) inverter-powered air conditioning?

Frigidaire FRA052XT7 5,000-BTU Mini Window Air Conditioner - with Remote Control

BTU 5,000 Amps 4.5 Watts 465 Weight 39 lbs. 12"/16"/15.25"



http://www.amazon.com/dp/B003KQUH0O

Works for me! I have some ideas for placement, but I would love to see your design and cabinet.
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Old 07-12-2013, 02:23 PM   #50
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Re: Generator versus idling small diesel?

Quote:
Originally Posted by E350
So what you're saying is that for $157.55, I could have shore-powered (and possibly, for short intervals) inverter-powered air conditioning?

Frigidaire FRA052XT7 5,000-BTU Mini Window Air Conditioner - with Remote Control

BTU 5,000 Amps 4.5 Watts 465 Weight 39 lbs. 12"/16"/15.25"



http://www.amazon.com/dp/B003KQUH0O

Works for me! I have some ideas for placement, but I would love to see your design and cabinet.
Just donít forget that 5000 BTU/hr isnít much capacity compared to typical RV A/Cs. It may be better than nothing but itís limited.

Anyway, in my case I screwed the A/C to a piece of plywood so I can move it in and out easily (remove in a few seconds and reinstall in less than a minute). The plywood is held in place by one wing nut for no-tool removal and reinstallation.

You have to be careful about sealing the A/C unit from leaking too much air from the front (van inside) although thatís not as critical. In my case I screwed aluminum angle to form the flange that bottoms against cabinet when A/C is pushed all the way in. That angle replaced A/C window mounting hardware. It also lets me know itís in all the way as far as needed to seal on back.

On the condenser side itís more critical that you seal it tight so that hot air discharged off the back of the A/C doesnít get sucked back to the supply side of the condenser fan (unless you include a supplemental blower). You can do that easily with a tight fit and some weather stripping along the edges. That allows the A/C to be taken on summer camping trips and removed if you know you wonít be needing it at all. I donít do that but in seconds could have a little more storage space by removing the A/C and leaving it at home.

Warning: Most window units work efficiently because they use condensation removed from the vanís inside to splash back on the condenser to get some evaporative cooling out of it. That reduces head pressure and makes the unit work better. In humid environment like I often use mine, the pan under the A/C will collect water that the condenser fan will splash on the condenser coil. By the way, thatís by design to make it more efficient. Anyway, if it is very humid, the pan will eventually overflow. In a window application it just drips out the back on the outside of the house, and why they tell you to tilt it backwards a little. In a van excess condensation could make a mess if you donít plan for it.

You could just drain it fully all the time so there is never much water in the pan (albeit at the cost of reduced performance) or you can let it overflow when it gets full just like in a house. In my case I didnít want the overflow to get the wood wet and warp things. For that reason I installed a slightly lower overflow tygon tube on the pan that drains to the outside through one of the 4-inch diameter openings on the floor. If I remove the A/C the very small tygon tube just comes out with it.

A couple of mornings after operation in extremely humid weather I could hear there was still water in the pan. In most cases Iíve allowed the unit to keep operating on fan mode for a while so the condenser fan would get most of the water out of the pan by splashing it onto the condenser and the fan blowing air across the wet coil. Once or twice under these circumstances Iíve removed the wing nut and slid the A/C forward to drain the pan manually. The A/C is not very heavy at all. Normally this is not an issue but Iím trying to make you aware of it. If I had to do it again I would probably fabricate a deeper impervious pan around the entire A/C and then drain that pan to the outside. In dryer weather this condensation issue doesnít come up in the first place. Also if doing it again I may try to place the A/C closer to the middle of the van and somewhat higher. Unfortunately in my case I needed to leave all windows unblocked.

If you want to keep things really simple, you can buy a ďportableĒ unit that has one or two hoses that vent to the outside of the van. In that case all you have to do is figure out how to connect the hoses to vent (or take suction from) outside. Even in that case I would use PVC fittings attached through the vanís floor because they are cheap, durable, and very easy to close off when not in use for extended periods of time. A portable unit only cost a few hundred more but may save you a lot of work and provide more cooling.

The greatest down side to a portable (versus smallest window) A/C unit is that they are typically larger and therefore draw more current; making inverter operation tougher. On the flip side the greater capacity would cool your van better when on shore power. As I mentioned before, 5000 BTU/hr is enough for us at night but leaves a lot to be desired during a hot day.

Anyway, good luck with whatever you decide to do.
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