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Author Topic: 24VDC generator UPDATE:  (Read 8221 times)
gr8njt
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« Reply #45 on: January 28, 2007, 03:23:44 PM »

[Gee. you do not run any air conditioning? In most of my 150,000 miles of travel in a conversion, the A/C was the most important appliance. Without it, all the others were of little benefit when I could not get comfortable. Travelling throughout most areas in the summer, the A/C run 24/7 for days on end.

the house bank is depleted down to 80% so as NOT to annoy the Walmart security guard or idle-free rest areas during the night..
If your batteries are only depleted 70 0r 80%, you will not be able to use a "Fast DC Charging" system without boiling your batteries. Even when the batteries are depleted to 50%, it is hard to maintain a fast charge with out boiiling them.

A well designed genset installation, properly quietened will meet all your requirements listed. I have never had a WalMart guard or idle free rest area guard question the operation of my quiet genset.
Richard
Richard,

Like most RV'ers, I am also a slave to the comforts of air-conditioning. In fact, when on the road, my bus air-conditioner freezes my buns off untill we get  plugged-in  at the camp ground destination, then the rooftop air-conditioners takeover and run 24/7.

What makes us (wife & I) different from other converters is the type of useage we do with our bus conversion. We have no plans to "full time" in any bus. We never intend to dry camp in any wilderness. We use the bus less than 5,000 miles a year. We love the shore and all our bus destinations are either ocean or lakefront campgrounds. Although I had made reference to Walmart parking lots and rest areas, we have never experienced overnight stays at these locations.  The possibility of it happening is remote but still possible so I think one night of no air-conditioning is tolerable till we get going very early the next morning.

As a last resort option however, if air conditioning is absolutely needed at Walmart parking lot, a properly geared/belted 175 amp 24V alternator can be spun by the small watercooled,  sound enclosed Kubota to keep a huge AGM battery bank  (400-600Ah@24V)  fresh to supply a Xantrex SW4024 to run one of my energy efficient 10A rooftop airconditioners.

We built the bus to travel in style and this bus is our "shore home" during these travels.  My wife and I have agreed that whenever we take the bus out to drive, there will be no pressure of time, traverse no more than 400 miles a day and drive only during daylight. We always plan our trips ahead of time so that we have educational/shopping/dining/relaxation stops along the way. Our destination/s are reserved a year ahead of time and are mostly 50 amp full hook-up service. 

Everyone has to understand that his is a "bus converters world" where only the imagination sets the limit to the possibilities.
That's why I built my own bus conversion the way I did. Does that make others wrong? NO. Not in a million years.
Richard, your bus design, use, and RV lifestyle is yours to be very proud off. 
I am just planning a system that will fit in our own type of bus use and type of stored (battery) energy consumption. 

However, in my persistent search for DC generator information, it seems that I had offended a few disciples of the AC generator God which is the farthest of my intentions. Neither do I want to debate AC vs. DC power generation. If I am not convinced to change my mind to switch to an AC generator, it is because I have already weighed my options and made up my mind as reflected in the first post of this thread.
 
In the 1st sentence of the 1st post of this thread I said: "I have decided to use a DC (24V) generator VS AC in my conversion".
My motive to harvest DC information is clearly reflected by my question at the end of the same post:
............................"Does anybody have a personal experience with DC generating?"
I started this thread to elicit useable info to support my project from knowledgeable, experienced busnuts in this type of undertaking, and busnuts like Niles500 that led me to Bill, Gary (Boogiethecat) with his 36 volt hybrid vehicle, Bill (Homegrowndiesel) who has the same Kubota motor and set-up as I was planning and who can unbelievably run his air-conditioner for 6 hours without running any generator, Stan with his dual 12 volt alternator suggestion, TomC for his battery type recommendation and everybody that chimed in with all useable technical info needed, Thank you.
Though it wasn't easy to keep my questions on track, this was a very productive info-gathering thread for me.



« Last Edit: January 28, 2007, 05:34:37 PM by gr8njt » Logged

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DrivingMissLazy
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« Reply #46 on: January 28, 2007, 05:23:59 PM »

Great. Now that I understand a little better your application then what you are doing makes perfect sense. Since my lifestyle was so much different, it was hard to imagine that you could be comfortable with what you planned.

BTW, although you would like to have a DC generator, there is no such animal in existence to my knowledge. Every rotating device produces AC power.
What is done with that AC power after it is produced makes the difference. Most available alternators generate the power at a higher frequency and take the AC and process it thru a full wave bridge rectifier to produce the DC power that you want. The AC is generated at the proper AC voltage level so that the DC output from the rectifier is the proper voltage to charge your batteries and operate your inverter and then operate your AC appliances

I personally prefer generating the AC at a standard voltage, and the proper frequency, so that it can be used to operate any of the AC appliances directly. Then use a step down transformer to reduce the voltage to that required for re-charging batteries. To me this eliminates the total dependence on an inverter, eliminates one level of inefficiencies and overall provides a higher level of reliability. It also, in my opinion, makes my concept much more attractive to a future owner.

But that is why we all elect to do some things differently. I think you have a good idea, for what you need, and wish you the best of luck in implementing it.
Richard
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gr8njt
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« Reply #47 on: January 28, 2007, 06:13:22 PM »

Great. Now that I understand a little better your application then what you are doing makes perfect sense. Since my lifestyle was so much different, it was hard to imagine that you could be comfortable with what you planned.
BTW, although you would like to have a DC generator, there is no such animal in existence to my knowledge. Every rotating device produces AC power.Richard
Richard,
The AC genset is your choice and I hope it keeps you comfortable and happy
No disrespect, but as I have said in my previous post, I have no interest to argue or debate the merits of using an AC genset to charge a huge (12/24VDC) house battery bank or supplying your 110AC needs directly.
I am also not looking for someone to convince me out of my current DC project.
I am, however, in search for helpful information  about efficient DC charging of a huge battery bank.

FWIW, check this link: www.stock-number.com/HUMMV-HMMWV-control-box.php
Apparently, they have Government and Military contracts and sell DC generators to the general public.
But then again, they could have misrepresented themselves.

Although not suited for my particular application, here's an interesting link for a "rotating device" that produces 24VDC.
It is used by the military to recharge batteries in their communication systems when out in the frontlines:
www.rfcomm.harris.com/products/tactical-radio-communications/12027-0000-01.pdf
« Last Edit: January 28, 2007, 07:17:11 PM by gr8njt » Logged

****1982 MCI-9 Crusader-II Bus Conversion****
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smooth side kit, dash-board kit, one piece siding
DrivingMissLazy
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« Reply #48 on: January 28, 2007, 07:16:13 PM »

No there is no mis-representation in the information as far as i can see from the information they provide.
The first device is a high frequency AC alternator whose output is directed thru a full wave bridge rectifier where the AC is converted to DC.
The second device is, I believe, closer to a DC device. It is similar to the old units we used to use to power the EE8 field telephones in the military and also similar to the generators on early automobiles. As Stan explained in a previous post, the output is AC and is converted to DC by use of the commutator segments and carbon brushes. A rotating armature device. The other device is a rotating field device. But both are generating an alternating current which is converted to DC by two different methods. At least that is my belief. LOL
Richard


Great. Now that I understand a little better your application then what you are doing makes perfect sense. Since my lifestyle was so much different, it was hard to imagine that you could be comfortable with what you planned.
BTW, although you would like to have a DC generator, there is no such animal in existence to my knowledge. Every rotating device produces AC power.Richard
Richard,
The AC genset is your choice and I hope it keeps you comfortable and happy
No disrespect, but as I have said in my previous post, I have no interest to argue or debate the merits of using an AC genset to charge a huge (12/24VDC) house battery bank or supplying your 110AC needs directly.
I am also not looking for someone to convince me out of my current DC project.
I am, however, in search for helpful information  about efficient DC charging of a huge battery bank.

FWIW, check this link: www.stock-number.com/HUMMV-HMMWV-control-box.php
Apparently, they have Government and Military contracts and sell DC generators. But then again, they could have misrepresented themselves.

Here's another link for a "rotating device" that produces 24VDC used by the military to recharge batteries:
www.rfcomm.harris.com/products/tactical-radio-communications/12027-0000-01.pdf
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« Reply #49 on: January 28, 2007, 07:40:43 PM »

... As Stan explained in a previous post, the output is AC and is converted to DC by use of the commutator segments and carbon brushes. A rotating armature device. ...


The link below is a site that has a nifty little demonstration of how this works and demonstrates through a simple JS controlled animation the differences between how an alternator and "dc generator" work (and how you are both right).

http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/generatorengl.htm

Most DC generation is now done with alternators using the previously described solid state circuits to rectify the AC into DC.   In a DC generator like once was used in cars,  the AC is rectified mechanically by the commutator.  In either case, rotating wires through magnetic fields produces alternating current and it is being converted to direct current. 
« Last Edit: January 28, 2007, 07:54:06 PM by HighTechRedneck » Logged
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« Reply #50 on: January 28, 2007, 07:51:49 PM »

Ray,

Here is a link to a site that has some useful informaiton on what you are doing.  The project used as an example appears to be smaller, but it covers a lot of the issues like pulley sizing for belt driven implementations and parts for direct driving.

http://theepicenter.com/tow123199.html

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« Reply #51 on: January 28, 2007, 09:00:37 PM »

One thing is the SW4024 that will help you out because then your options are open.  It'll monitor and handle it all for you.  It was originally designed to sell power back to the grid and run buy itself for long periods of time  Once you have it your options are open  just remember it has an efficiency curve and is really ineficient at low draw, can run in standy by when needed.  It can monitor the batteries and start/stop generator as needed all while you snore or prance around the museum Cheesy  It has a built in 60amp trancfer switch and will do the ac synchronizing for you, pole or genny.  And it will draw from battery if shorepower needes help.  One argument for AC genny is that the the SW4024 will operate for you.  However, if you have start/stop relays, then it may work it anyway. you have options to generate DC via solar, windmill, running on veggie oil, or whattever your contraption is and let the bus at least pay your power bill while it's parked out back.

remember you only have half the amphours that your stickers on you batteries say and then look at the effeciency curve on the trace.  that way you want be disapointed whith what you really have.

Do it your way!! Smiley
« Last Edit: January 28, 2007, 09:06:12 PM by NewbeeMC9 » Logged

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DrivingMissLazy
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« Reply #52 on: January 28, 2007, 10:05:19 PM »

WOW. What a neat referral. I wish I had known about this earlier. Thanks very, very much. As is often stated, a picture is worth a thousand words.
Richard


... As Stan explained in a previous post, the output is AC and is converted to DC by use of the commutator segments and carbon brushes. A rotating armature device. ...


The link below is a site that has a nifty little demonstration of how this works and demonstrates through a simple JS controlled animation the differences between how an alternator and "dc generator" work (and how you are both right).

b]http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/generatorengl.htm[/b]
Most DC generation is now done with alternators using the previously described solid state circuits to rectify the AC into DC.   In a DC generator like once was used in cars,  the AC is rectified mechanically by the commutator.  In either case, rotating wires through magnetic fields produces alternating current and it is being converted to direct current. 
« Last Edit: January 28, 2007, 10:09:05 PM by DrivingMissLazy » Logged

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« Reply #53 on: January 29, 2007, 12:54:19 AM »

HighTechRedneck to the rescue!  Very nice link. 

 http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/generatorengl.htm

If you go there and click on 'with commutator' in the upper right corner you will see what a simplified DC generator wave form looks like. It has been repeated several times in this thread that a DC generator somehow converts AC into DC by using the commutator.  Huh  There is no AC, just pulses of DC which the battery very effectively filters to nice smooth DC. 

Does not really matter since the only reasonable way to charge batteries using rotational forces today is with an alternator. Grin

So how long would I have to hand crank that 60watt rig to start my Jimmy diesel if the batteries were dead!!!!!  Cry Cry
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gr8njt
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« Reply #54 on: January 29, 2007, 04:20:53 AM »


Does not really matter since the only reasonable way to charge batteries using rotational forces today is with an alternator. Grin
You're absolutely right Don4107.
I don't know why there is a debate on the technical production of how a DC is created via a rectifier in an AC alternator.
All these technical info is helping us get educated on electrical production and it is greatly appreciated.
However, these arguments are bogging down the flow of right info I need to move my project forward.
I understand a lot of people know their electrical stuff, but how will all these technical info help this project?

The bottom line this project is:
>>>> I will be using an automotive type 12 or 24 volt alternator to directly charge my 24V battery bank
..................................... to be driven by a small water-cooled diesel fired Kubota engine
<<<<<<<
So some helpfull information would be: 
>>>1. How to move and store the 12 or 24 volt energy produced by the alternator to the battery bank.
>>>2. How to prevent unneccesary energy losses towards the storage bank.
>>>3. How to harness the most energy out of a 12 or 24 volt automotive alternator.
>>>4. How to keep/maintain the stored energy at safe levels.
>>>5. What storage batteries are best recommended for renewalble energy use in an RV
>>>6. You recommendations here......
« Last Edit: January 29, 2007, 04:28:47 AM by gr8njt » Logged

****1982 MCI-9 Crusader-II Bus Conversion****
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« Reply #55 on: January 29, 2007, 05:01:20 AM »

Don, I have to disagree with you. The AC is there and it is commutated to DC. Again I thank HighTechRedneck for such an excellent referral. This is the same thing that a silicon diode does in the current automotive alternator except the diode does it electrically instead of mechanically. This eliminates the requirement for the heavy carbon brushes and the commutator bars which were always a source of maintenance and failure.
Richard


HighTechRedneck to the rescue!  Very nice link. 

 http://http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/generatorengl.htm

If you go there and click on 'with commutator' in the upper right corner you will see what a simplified DC generator wave form looks like. It has been repeated several times in this thread that a DC generator somehow converts AC into DC by using the commutator.  Huh  There is no AC, just pulses of DC which the battery very effectively filters to nice smooth DC. 

Does not really matter since the only reasonable way to charge batteries using rotational forces today is with an alternator. Grin

So how long would I have to hand crank that 60watt rig to start my Jimmy diesel if the batteries were dead!!!!!  Cry Cry

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« Reply #56 on: January 29, 2007, 06:26:40 AM »

gr8njt: This is the best I can do on your six questions.

1 and 2: Are you asking for a recommendation on cable size.

3 and 4: According to an article I read yesterday in the newpaper (I can't find a website) the best way is elctrolysis to convert electricity to hydrogen, stored at low pressure and used in a fuel cell. I jnow that this has nothing to do with your project, but it is an answer to your question.

5: No opinion

6: A lot of your posts indicate that you are not receptive to recommendations for a different way,  but just want someone to do the technical design for your idea. You have done a lot of research on theory, but you don't seem to have started on the practical aspect of putting the theory to work. You have the cart before the horse by buying the engine first and trying to design a system around the engine instead of getting a prime mover (which might turn out to be an integrated unit)  last to fit the sytem.

My suggestion is that you get your design done and then ask specific questions that can be answered with a technically correct answer. That may be what you did in 1 and 2 above but the question is not clear.  You have to help us to help you.
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« Reply #57 on: January 29, 2007, 07:45:29 AM »

The bottom line this project is:
>>>> I will be using an automotive type 12 or 24 volt alternator to directly charge my 24V battery bank
..................................... to be driven by a small water-cooled diesel fired Kubota engine
<<<<<<<
So some helpfull information would be: 
>>>1. How to move and store the 12 or 24 volt energy produced by the alternator to the battery bank.
>>>2. How to prevent unneccesary energy losses towards the storage bank.
>>>3. How to harness the most energy out of a 12 or 24 volt automotive alternator.
>>>4. How to keep/maintain the stored energy at safe levels.
>>>5. What storage batteries are best recommended for renewalble energy use in an RV
>>>6. You recommendations here......

It appears to me that in between the discussions on clarification of terms and electrical generation methodology, that you have already gotten some pretty good information on the engineering of the system and battery types/sizes.  Here are a couple observations:

1-2:  Keep the low voltage DC cable runs as short as possible and use the largest available gauge of cable to minimize cable loss.
3  :  Design the pulleys to run both the engine and the alternator at their respective optimum RPMs.
4  :  Use a microprocessor based charge contoller that is programmed for your specific batteries.
5  :  There don't seem to be any definitive studies publishing efficiency ratings between different deep cycle batteries, but there have been several good reccomendations from experienced people already in this thread.  Also, do a forum search on "deep cycle battery" and it will produce results from other threads on battery banks that have been extensively discussed before.
6  :  Through this thread you have found a few people that already have or are currently doing the same thing you are.  They will be your best sources of advice.  To minimize distractions, you may even want to take up private discussion of the project with them.  Public discussion will get the widest range of ideas, which is good and we all benefit from it, but that diversity of ideas and opinions brings a certain amount of distraction with it.  That said, I hope you will keep your project discussion public as this is an interesting topic that everyone can learn from.
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captain ron
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« Reply #58 on: January 29, 2007, 07:49:42 AM »


BTW, although you would like to have a DC generator, there is no such animal in existence to my knowledge. Every rotating device produces AC power.Richard
Richard,
 
dynamo crank,  Maybe I'm wrong but is this not DC and does it not rotate?  Grin  Just for sh!ts and giggles could you possibly build a battery charger with this technology? A lot of gear reduction to make it usable I would presume.
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captain ron
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« Reply #59 on: January 29, 2007, 08:05:42 AM »

Here is a link on electricity storage. Don't know if it will help or not. Has different battery technologies.

http://electricitystorage.org/tech/technologies_technologies.htm
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