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I have decided to use a DC (24V) generator VS AC in my conversion.

My research pointed the fact that DC generors are much more efficient than AC generators.
There is MINIMAL wasted energy everytime the DC generator is running because all the amps are directed to the house batteries for storage and the inverter produces the AC power needed in the coach from that stored energy.
They are apparently more preferred by the marine industry.

Additionally, when on the road, the 270 amp Bus alternator can fully charge the 24 volt house batteries.

My search took me to the G24/175 made by Ample Power (http://amplepower.com/products/genie).
This DC generator (G24/175) is an ideal partner(sold separately) to the Trace SW4024 (4000 watts Sine wave),
and produces 5000 watts of DC charge to keep up with the SW4024 inverter demand.

Does anybody have personal experience with DC generating in general?
Any other options on DC generators?

To my knowledge, DC generators have not been manufactured in many many years. All the DC components on any vehicle for the past 30-40 years have been alternators instead of generators. The alternator is an AC device that internally rectifies the AC produced to DC.
Richard

Quote from: DrivingMissLazy on January 23, 2007, 06:01:50 PM
To my knowledge, DC generators have not been manufactured in many many years. All the DC components on any vehicle for the past 30-40 years have been alternators instead of generators. The alternator is an AC device that internally rectifies the AC produced to DC. Richard

Ample Power presently makes 24Volt DC gensets (http://amplepower.com/products/genie) (up to 175 amps DC) to charge any House battery bank. They also make enclosures (optional) for quiet operation. Click the underlined link for more details of this product and scroll all the way down to the bottom of the page.

I do understand that the bus (or any vehicle in the past 30-40 years) uses an alternator to charge the bus battery bank when on the road.
However, when properly equipped with an "Isolator" between the bus battery and the house battery, the bus alternator can charge both battery banks simultaneously when the bus engine is running.  When the bus engine is turned off, the "Isolator" automatically separates the bus battery bank from the house battery bank so that the bus battery bank does NOT get depleted during dry camping.  At this point, both banks are fully charged.

Like I mentioned earlier, the DC genset sends ALL of the amps generated to the house batteries. In comparison, AC gensets have minimal DC amp charging (although some use inefficient inverters/chargers for more amps to the battery) and it would take hours to fully charge a HUGE house battery bank while running the AC genset at optimum rpm.

The DC genset is very efficient and dependable in the Marine industry. Has anyone used this system in a Bus Conversion?
Any info will be appreciated.

gr - Bill Glenn has been toying with the same idea - you might contact him from the board profiles and see if he has can be of any help - handle is "homegrown diesel" - HTH

How do they cool the unit pictured?  Looks like a marine unit.    Do they have a "stationary" radiator package that could be supplied?  How much will that add to the cost of the unit? 
I have one of those tiny Kubotas, but it has a belt driven water pump where that spigot is located on the pictured engine.   
I can attest that the little Kubota twin will run on diesel fumes.   It'll also crank in 10* weather without aids.
Also add that they are noisy unless very well isolated. 
Interesting angle!
BTW, the Chinese are producing Kubota "style" engines that are to be avoided at all cost....be sure that you're buying a genuine Kubota.   
You could buy a Kubota industrial engine and attach it to a 24V bus belt driven alternator and have a similar item...output would be DC of whatever size alternator you buy.   
Unlike the critical speed governing of 120 VAC generation units, the engine RPM could be anywhere within reason using an automotive or bus alternator. 
JR 

Did you read the AD? It specifically states that they use AC alternators.
Richard

Quote from: gr8njt on January 23, 2007, 06:46:09 PM

Quote from: DrivingMissLazy on January 23, 2007, 06:01:50 PM
To my knowledge, DC generators have not been manufactured in many many years. All the DC components on any vehicle for the past 30-40 years have been alternators instead of generators. The alternator is an AC device that internally rectifies the AC produced to DC. Richard

Ample Power presently makes 24Volt DC gensets (http://amplepower.com/products/genie) (up to 175 amps DC) to charge any House battery bank. They also make enclosures (optional) for quiet operation. Click the underlined link for more details of this product and scroll all the way down to the bottom of the page.

I do understand that the bus (or any vehicle in the past 30-40 years) uses an alternator to charge the bus battery bank when on the road.
However, when properly equipped with an "Isolator" between the bus battery and the house battery, the bus alternator can charge both battery banks simultaneously when the bus engine is running.  When the bus engine is turned off, the "Isolator" automatically separates the bus battery bank from the house battery bank so that the bus battery bank does NOT get depleted during dry camping.  At this point, both banks are fully charged.

Like I mentioned earlier, the DC genset sends ALL of the amps generated to the house batteries. In comparison, AC gensets have minimal DC amp charging (although some use inefficient inverters/chargers for more amps to the battery) and it would take hours to fully charge a HUGE house battery bank while running the AC genset at optimum rpm.

The DC genset is very efficient and dependable in the Marine industry. Has anyone used this system in a Bus Conversion?
Any info will be appreciated.

Quote from: DrivingMissLazy on January 23, 2007, 08:21:36 PM
Did you read the AD? It specifically states that they use AC alternators.
Richard

Hate to bust your bubble or start a fight but Qoute from web site"Charging batteries from an alternator is much more efficient than going through an AC generator and a battery charger. That's why we use Kubota diesels to drive large frame DC alternators ...to charge batteries fast and full."

I'm all for a big inverter to run an A/C or whatever when the bus is running.  Is 33 amps going to be enough AC power?  That's what a 4000 watt inverter produces.  There's also no redundancy in that system.  With an AC genset, you have power if there's a problem with the inverter.  If the genset has issues, the inverter can provide limited power (no A/C, though) for a while, depending on your battery bank.  I'm sure the system you propose will work, but it sure seems like a round-about way to get AC power.

David

JR, I do not know how these Kubota units cool. Thanks for the info as I may end up fabricating my own hybrid system using a small diesel engine running a large (maybe 270 amps) 24VDC alternator used in trucks or buses. I'm still in the research stage of the project.

Quote from: DrivingMissLazy on January 23, 2007, 08:21:36 PM
Did you read the AD? It specifically states that they use AC alternators. Richard

Richard, Yes, I've read it very closely and the AD states that they use DC alternators with their Kubota engines.

David, I pondered that angle for a while.  And yes, if the inverter fails, there'll be no AC power in a single inverter set-up. I already have a small Xantrex 24 volt modified Sine inverter/charger which will be a back-up to a larger pure sine 4k inverter/charger. Or if finances is not too much of an issue, I may stack two (2) 4k inverters together.  Also, in this system, a huge battery bank is an integral part to factor in.

If you're talking about efficiency, producing 120v through an inverter is about as inefficient as it gets.  First you have a 12v (or 24v) alternator to produce electricity.  There is efficiency loss in that since you are only using one side of the sine wave on a 3 phase alternator to produce the DC voltage.  Then there is the loss through the electrical cables to the batteries (why do you think we use AC current all over? Because it was discovered very early on in electrical development that DC current does not travel well for any kind of distance over wires).  Then there is another efficiency loss at the batteries.  Then another efficiency loss again with the battery cables going to the inverter.  Then the inverter has efficiency loss also.  If you take 10% loss for the Alternator, 5% for the battery cables, 10% loss for the batteries, 10% loss at the inverter, you're at only 65% efficient.  Now compare that to a straight generator that is usually around 93% efficient producing the power once, then transmitting it directly to your sources.

I also have an inverter/charger.  The charging side can be adjusted up to 130 amps and is a three stage adjustable to your type of battery you are using.  Personally, I like to think of the inverter as 120v power for intermittent use-like for the coffee maker, toaster oven, microwave, powering low draw stereo and TV, refrigerator, etc.  If you want to power the air conditioner, run the 120v generator.

That 1 cylinder Kubota is aimed at blow boaters that don't have enough accessories to warrant a normal generator, but need some sort of stand by power so they don't have to be running the main propulsion engine just to charge the batteries.  Believe me when I say your electrical requirements on the bus (especially if you have 2 or 3 air conditioners, electric heat, electric water heaters,etc) are way above what that little Diesel powered 12 charger is capable of producing.  That Kubota engine is probably only about 8hp, compared to the 18hp on a 10kw gen like I have.  If you have a question about using a new idea, just look at what everyone else is using and ask them why they are using the systems that way.  It'll save you alot of grief down the road.  Good Luck, TomC

Boy you take the fun out of every thing >:( ....

Quote from: TomC on January 23, 2007, 10:39:07 PM
If you're talking about efficiency, producing 120v through an inverter is about as inefficient as it gets.  First you have a 12v (or 24v) alternator to produce electricity. There is efficiency loss in that since you are only using one side of the sine wave on a 3 phase alternator to produce the DC  voltage.   I also have an inverter/charger.  The charging side can be adjusted up to 130 amps and is a three stage adjustable to your type of battery you are using.  Personally, I like to think of the inverter as 120v power for intermittent use-like for the coffee maker, toaster oven, microwave, powering low draw stereo and TV, refrigerator, etc.  If you want to power the air conditioner, run the 120v generator.
Good Luck, TomC

All points well taken. Thank you.
Since we are talking about charging a battery bank using DC genset, please explain the highlighted statements further though. I thought all along that modern bus/automotive  alternators produce DC amps directly to the battery. Your statement above indicates that DC amperes are being produced from one side of the sinewave on a 3-phase alternator. If I am confused,  please explain as my research says otherwise.

Or if anyone can school me on automotive DC charging.  My goal is to charge a big house battery bank in the least amount of time,  least use of fuel and without the use of the grid.

Quote from: gr8njt on January 24, 2007, 04:45:26 AM
I thought all along that modern bus/automotive  alternators produce DC amps directly to the battery

Alternators produce alternating (AC) current.  The AC is rectified by the diodes in the alternator to produce the DC used for charging and the vehicle's elec. system.

David

My answer would be to use an automotive type alternator with a three stage regulator on the alternator. To obtain the best efficiency, you need to know the maximum current that your battery bank can use and then size the alternator and engine to get peak efficiency at that current. The last 10% of battery charge takes time and can't be avoided regardless of the system used.

BTW: an automotive alternator is three phase AC into a full wave three phase bridge rectifier. This uses both halves of the sine wave from all three phases with minimal ripple.

Quote from: Stan on January 24, 2007, 05:24:39 AM
My answer would be to use an automotive type alternator with a three stage regulator on the alternator. To obtain the best efficiency, you need to know the maximum current that your battery bank can use and then size the alternator and engine to get peak efficiency at that current. The last 10% of battery charge takes time and can't be avoided regardless of the system used.

BTW: an automotive alternator is three phase AC into a full wave three phase bridge rectifier. This uses both halves of the sine wave from all three phases with minimal ripple.

Thank you Stan for a very informative post.
Please help me with this math:
I would like to use a Xantrex SW4024 (or any efficient 4kw inverter/charger) from a bank of four 200Ah 12V AGM batteries.
If the batteries were wired in series to produce 24 volts, I should have a 400Ah. Correct?
Using the SW4024 at maximum AC use of 4kw, the inverter will draw about 35 amps (110v) AC = 175 amps (24v) DC. Right?
If I find a 200 amp 24V automotive alternator, would this be sufficient to charge this bank of 400Ah without discharging it beyond 50%?
Do you think I need a larger battery bank? Do you suggest a more powerfull alternator for quicker bulk charging?

FWIW, my coach & H2O heating will eventually be the "Pro-heat" system.  The electric system I have in place now will be the "on grid" back-up system for some redundancy.

Then you caould do aircraft AC and have lighter wieght components using 400 cycle three phase.

I have been told that all automotive type alternators are high frequency in the 4-6,000 Hz. range. That is why they can output full capacity over a very wide rpm range and are of course much smaller than a 60 Hz. alternator. Also, the higher frequency gives a much lower AC ripple on the DC output. And they are three phase full wave rectifiers for minimum ripple.
Richard

All DC generating on todays cars and trucks are done with alternators.  They are all 3 phase (120 degrees apart) so that even when you install the three diodes (diodes are electronic devices that go inline that allows electricity to only flow one direction-hence no more alternating current, just direct current) the electrical flow will be smooth (rather than single phase that would make for flashing lights).

Now for your 4kw inverter.  I think you're looking at the mathematical requirements backwards.  With 4kw, from the 24v power source you will need about 185 amps of battery power (figuring 90% efficient on the inverter).  With any battery bank, to get maximum battery life you don't want to run the batteries down more than 50%.  So now your advertised 400 amp hour battery bank is only 200 amp hours.  That means at full power on the inverter you have about 65 minutes of electricity.  Even if your average electrical requirements are only averages 1200 watts per hour for 24 hours, you would need a battery bank (again figuring 50% discharge only) of 14 AGM batteries.  Or if you use the AGM 8D batteries like I have, they are rated at 255 amp hours.  Again at 1200 watts per hour for 24 hours, you would need 10 8D's at 155lb apiece, or 1550lb of batteries.  That's about 3 times what my 10kw generator weighs.  My personal usage and my VERY strong suggestion- use a Diesel gen and the inverter for additional standby power.  If you do any kind of boon docking, you'll be the happiest.

The only propane on my bus is the stove and furnace.  My reefer and freezer are Norcold compressor type 12v/120v, 2-10gal elec water heaters piped from one into the next with the final water heater wired through the inverter, electric heat in the bathroom, 3-roof air conditioners with heat strips, microwave, TV, Stereo, etc.  I have just 2 8D AGM's.  When boon docking I just run the gen in the morning for coffee and to get the water heated (we take morning showers) and to charge the batteries.  Run it again at dinner if needed to float the batteries again.  The trick is to have a generator that is extremely quiet.  My could be quieter.  It is actually noisier inside than outside-which doesn't bother me since I'm more concerned with my neighbors.  Please reconsider your electrical methodology!

Richard-car alternators frequency is whatever rpm they are running at.  With a bus and the 50DN, my gear drive is 2.75 to one.  So at 2100rpm the alternator is running at 5775rpm. That translates into 192 cycles per second (or for 3 phase 576 cycles per second total-compared to 60 cycles per second for household electricity).  Good Luck, TomC

Thank you for everyones input. All suggestions/opinions are greatly appreciated.
Like I said earlier, I'm still in the research phase so the more informative data that comes by,
the better for my project analysis at the end of each day.

Richard: I think automotive alterantors are 12 pole so that gets them up to 6 khz at 5000 RPM. Sometime back someone did all the calculations to figure out the number of pulses related to speed when hooking up a tachometer to the alternator.

Richard-car alternators frequency is whatever rpm they are running at.  With a bus and the 50DN, my gear drive is 2.75 to one.  So at 2100rpm the alternator is running at 5775rpm. That translates into 192 cycles per second (or for 3 phase 576 cycles per second total-compared to 60 cycles per second for household electricity).  Good Luck, TomC

Tom, alternator frequency output is determined by rpm and number of poles in the alternator.  A household 1800 rpm alternator has four electrical poles, a 3600 rpm alternator has two poles, each delivering 60 hertz at rated RPM.

The formula for finding hertz is: rpm times number of poles divided by 120. For example  an 1800 rpm, four pole alternator will generate 60 hertz.  1800 X 4/120=60. Single or three phase has absolutely nothing to do with it. Since you do not define the number of poles in your example, it is impossible to determine the output frequency.

Using your example of 5775 rpm, a 12 pole alternator would produce 5,575 hertz, single or three phase depending on how the alternator is wound. Automotive alternators are all wound for three phase output. The frequency would vary as the rpm varies.
Richard
PA Stan and I both believe the standard number of poles for automotive alternators is 12.

When I first proposed the idea that I can built my own RV, my entire family almost chocked laughing.
When I tell other people I am building my 2nd RV using a "Greyhound type" bus, they look at me like I am high on something.

I know this topic is almost taboo here, but as usual I  am always trying to think outside the box so I  took the plunge and purchased  this complete brand new Kubota water-cooled diesel engine to spin a 24 volt high amp automotive alternator. This will be the start of this project. As soon as the engine gets delivered, I will start designing and fabricating "isolator" motor mounts,  a slide-out,  adjustable alternator mount and a "quiet" box.

I am presently watching a 24volt 105 amp single wire alternator on ebay going for $50 and see how lucky I am.
I am still on the hunt for an elusive higher amp 24V alternator close to 175-200 amp range. If somebody knows a source of one,  I would appreciate if you direct me to it.

gr8njt: A single wire alternator has an internal voltage regulator and you will not be able to set it at the voltage you need for your particular type of battery. You need an alternator that uses an external regulator so that you can use a muti stage charging voltage.

Any of the places mentioned on the board that dismantle buses will have belt driven 50 DN alternators that are 270 amps at 28 volts.

Quote from: Stan on January 26, 2007, 05:45:00 PM
gr8njt: A single wire alternator has an internal voltage regulator and you will not be able to set it at the voltage you need for your particular type of battery. You need an alternator that uses an external regulator so that you can use a muti stage charging voltage.
Any of the places mentioned on the board that dismantle buses will have belt driven 50 DN alternators that are 270 amps at 28 volts.

As usual, you come up with very helpful info Stan. Thanks. I will surely look for a used 50DN alternator at Camp Luke.
I am also looking at DEKA UNIGY non-spillable Industrial 12 volt batteries rated at 150 amps each.
What do you think of them?

gr8njt: I don't know anything about those particular batteries.

It sounds like you are starting a project that requires a lot of mechanical end electrical engineering knowledge, which you may or may not have. If this is just a fun project where capital cost, operating cost, size, weight  and maintenance are not a factor, then have fun, but don't do anything that will get you hurt.

If you are trying to build a fuel efficient, cost effective system then here are a couple of pointers for you to start with.

1. The engine speed will be determined by the point where the horsepower curve crosses the torque curve.

2. The rear main bearing on an automotive type engine is not designed for side loading. This means that you have to have a coupling of the flywheel to a driveshaft or flexible coupling to a jack shaft that hold the belt pulley. The engine manufacturer may have a bell housing and outout shaft for this purpose. This will be quite a large pulley with at least four V-belt grooves and the diameter will be deternined by the size of the pulley on the alternator, to get optimun efficiency out of the alternator.

3. Just designing the pulley diameters and belts is a speciality in itself. The size of the jack shaft and its supporting bearings are critical to not having a catastrophic failure. The major power transmission companies have a lot of help on this point.

4. Your maximum electrical load will be handled by a combination of alternator capacity and size of battery bank. These have to be calculated to get the most hours of use with the fewest number of hours of generator time wjile balancing the cost and weight of batteries to the cost of running the generator.

GR8NJT- Since it seems you've decided to go this route of making your own low volt system, I'd like to make some suggestions.  First- buy all equipment that is readily available on the road-or in another words, don't buy off beat stuff that is only made in one part of the country (like those Deka Batteries).  If you want AGM batteries that are spill proof, etc (personally have 2-8D Lifeline AGM's and love them), stick with AGM batteries that are made in normal automotive sizes (like 8D, 4D, 31, 6v golf cart) so you can easily replace them anywhere in the country, and if need be can replace them with wet leaded batteries, since AGM's and wet batteries can be charged the same. 
Delco is making some really nice alternators.  Some are brushless, and will operate at higher temps (because of the higher under hood temps now).  The DN50 is really the ultimate alternator (mine is gear driven for no belts-as a matter of fact, I have NO belts at all on my engine), but it requires a pressured oil hook up since it is cooled by oil (sealed, brushless, cooled and lubricated by pressured oil) and I think it would be too hard to adapt to a small Kubota.  There are air cooled replacement alternators for the 50DN that would be more suitable.
On the Kubota engine.  Any of the Kubota engines are just about as close to 100% reliable as you can get with an engine.  But- I would stay away from both the 1 and 2 cylinder because of vibration.  Kubota makes a mini series that has a 3 cylinder that would be very smooth and long lasting.  Running at about 2400rpm, (1800rpm is actually too slow for the small Diesels-as we will find out when Tier 4 emissions are attempted.  You'll see the small Diesels sped up to the 2500-3000rpm range to get into their power curve that will clean up the exhaust), and could run two, three, four smaller alternators.  The alternators that are run on trucks can be bought for about $250 new!  Then if one goes out, can get it at any truck parts place.  Good Luck, TomC

Further to what Stan says, coupling the alternator to the engine in line will create a very long unit. Torsional rigidity is very necessary in this type construction. I manufactured a lot of units coupled end to end and to attain the necessary rigidity, I would typically weld together two six inch sections of "C" channel angle iron or whatever width channel required for the base required. Sometimes three channels were required, based on the mounting hole dimensions of the motor and alternator. Cross pieces on the bottom of the base were then welded on to attach the vibration isolation pads to. It was generally a very heavy piece of machinery and typically not suited for installation in a coach.
The units I manufactured were typically an electric motor driving an AC alternator to provide clean power for a computer system. Anywhere from 5kva to several hundred kva.
A good rule of thumb to use when manufacturing engine driven gensets is to use two hp per kw. In other words if you want to generate 10kw of power an 18-20 hp engine should be selected. This will keep the engine at about 80% load when the alternator is producing 10 kw and you never want to run the engine at full rated hp continuously.

Richard

Quote from: DrivingMissLazy on January 27, 2007, 08:09:43 AM
A good rule of thumb to use when manufacturing engine driven gensets is to use two hp per kw. In other words if you want to generate 10kw of power an 18-20 hp engine should be selected. This will keep the engine at about 80% load when the alternator is producing 10 kw and you never want to run the engine at full rated hp continuously.

Richard

That translates to 14-15 hp for a 270 amp 50DN @ 28v.

Len

I would like to see the drive end of the engine that you have ordered. Also, are you open to any suggestions as to how to accomplish what you want to do?
Richard

Quote from: DrivingMissLazy on January 27, 2007, 04:06:34 PM
I would like to see the drive end of the engine that you have ordered. Also, are you open to any suggestions as to how to accomplish what you want to do? Richard

I have reassesed my position on the use of 50DN 270 amp bus alternator.
I am seriously and patiently looking for 175 amp 24 volt automotive alternator to match a 3kw-4KW sine-wave inverter/charger.

Installation of "Proheat" for radiant heating and water heating is in the works sometime before next winter. This makes my present electrical water/heat as "back-up" systems and for campground convenience.

Therefore my goal on this project is:
To fabricate the fastest charging time on a 300-400Ah battery bank from the smallest possible water-cooled diesel engine which I just purchased. This alternator should be able to keep-up with a 3kw-4kw inverter use. I do not intend to "fulltime" or dry-camp for extended periods of time. A weekend is the MOST I would dry camp. I use my bus basically from home to campground and would like to be self sufficient for 24-36 hours MAX when resting at a Walmart and/or rest area. One reason for my choice of a 24 volt system is to have the charging done on both the bus and house 24 volt banks at the same time WHILE the bus is running. This gives me a full house charge to use before I run the small Kubota.

Richard, I am always open to suggestions on any of my projects.  Here's a pic the drive end of the genset and a few wiring diagrams that I may need I obtained from my research. Thank you.

Sure is a cute little bugger  :)

Quote from: TomC on January 27, 2007, 08:01:32 AM
If you want AGM batteries that are spill proof, etc (personally have 2-8D Lifeline AGM's and love them), stick with AGM batteries that are made in normal automotive sizes (like 8D, 4D, 31, 6v golf cart) so you can easily replace them anywhere in the country, and if need be can replace them with wet leaded batteries, since AGM's and wet batteries can be charged the same. 
Good Luck, TomC

Points well taken. That's what I will hunt for. Thank you.

One thing you could do to make the alternators easier to find is use two 12 volt alternators and hook em in series, then hook them to groups 12 volt batteries in series to get your 24 volts. The "center tap" between the two alternators must be hooked to the "center tap" between the 12 volt banks.   One alternator would have to be mounted totally insulated, because it's frame is going to be at 12 volt potential.
  I used this technique quite sucessfully to create a simple charging system for a hybrid electric vehicle running at 36 volts... three banks of 12 volt batteries in series, and three alternators, basically one alternator dedicated to each 12 volt bank (two of the alternators had to be mounted insulated in this app)
  The advantage is that each alternator takes care of it's own 12 volt battery bank independantly of what is being drawn from the overall system, thus you can tap 12 volts, 24 volts or in my case 36 volts from the system for various doodahs without a balancing problem.  And a 175 amp 12 volt alternator is probably going to be a lot easier to find...
Belt drive them, it's a no brainer...
Cheers

Looks like a v-belt drive so belt drive should not be a problem as Stan mentioned.
Richard

Well Ray,

Glad to hear from others that think the same way.

I have the same engine and just bought a SW 4024, along with 2 used 280 amp 24 volt DC liquid cooled alternators.(Flea market at Arcadia)

Efficiency is easily measured in amount of $ used to generate useable energy, or more accurately described as converted to useable energy. 

A small amount of fuel can easily charge 20 amp to top off charge for barreries. With an AC unit 1800 or 3600 is required. DC can idle the engine to top off the batteries.  A certain amount of fuel is needed to detonate each revolution.


Your use sounds alot like mine also.

The proper plumbing routes the heat from that little diesel into the valved, Proheat, Engine loop. 33% efficiency turns into 66% during cool weather when some heat is needed. Add another 25% total efficiency because when you need potable hot water you can recover, I mean convert the otherwise waste heat into useable potable hot water. Of course use it to preheat your engine and add an air compressor to air up your bus for departure.


I chose 1200ah, This gives me 1 week of general lighting, water pumping, and potable hot water when used with the Proheat, or 2 days if the proheat - Webasto is run for cold weather, (not just for hot showers), or 6 hours of relaxing overnight sleeping with ac running.

I guess I am a glutton for punishment, But I Googled efficient alternator DC and found the 300 amp Alternator I tried. Worked good for 3 years so far but I have really cooked this thing at low rpms with limited airflow. (most efficient for power used according to the US grant sponsored report) Going Liquid cooled this time(easier to recapture, and control)  I agree, be gone the next day with on the road AC kicking and alternator recharging as we go to wherever we are headed.

I was looking for an inexpensive 24 volt alternator, but only found internally regulated intermittent duty cycle 25% rating at full listed capacity.. Not what I really needed.

Anyway, the key is the drive ratio on an inexpensive system. Set up properly, the rpm that the alternator makes power can be adjusted so as to not overload the engine. properly geared(belted) you are not overdriving(running to capacity) either unit.

Or a properly written logic that Responds with throttle control, and amp draw, voltage control to the field coils, will be the best for automated efficiency.

I have used rocks of various sizes to manually adjust my fuel consumption (hold open the throttle) and amp, as well as Air conditioning output.

Oh yea, you can also run it off of the oil you deep fry your turkey in. (just about the same amount of time passes for the amount of oil usedm (in generator) as turkey ate)

I should have run over to Bruces the other day when you came down. We have alot to talk about.

Catch you later

Bill

Also, proper placement would eliminate axial strain on the engine bearings.

Ed

As long as you are not using the AC component to drive something that is frequency sensitive, you can operate an 1800 rpm alternator from 1250 rpm to 2250 rpm without any problem. The AC frequency will vary with rpm, but the voltage regulator will maintain the output within about 5 percent.
I have a patent on a device that I invented and I used this exact technology. I was spinning a flywheel at the higher rpm and letting it coast down to the lower rpm while converting the AC to DC and operating a PWM inverter at 300 volts DC. I increased the ride thru of a flywheel motor generator set by about 1700%.
Richard

Quote from: Homegrowndiesel on January 27, 2007, 07:06:21 PM
Well Ray,

Glad to hear from others that think the same way.

I have the same engine and just bought a SW 4024, along with 2 used 280 amp 24 volt DC liquid cooled alternators.(Flea market at Arcadia)

Efficiency is easily measured in amount of $ used to generate useable energy, or more accurately described as converted to useable energy. 

A small amount of fuel can easily charge 20 amp to top off charge for barreries. With an AC unit 1800 or 3600 is required. DC can idle the engine to top off the batteries.  A certain amount of fuel is needed to detonate each revolution.


Your use sounds alot like mine also.

The proper plumbing routes the heat from that little diesel into the valved, Proheat, Engine loop. 33% efficiency turns into 66% during cool weather when some heat is needed. Add another 25% total efficiency because when you need potable hot water you can recover, I mean convert the otherwise waste heat into useable potable hot water. Of course use it to preheat your engine and add an air compressor to air up your bus for departure.


I chose 1200ah, This gives me 1 week of general lighting, water pumping, and potable hot water when used with the Proheat, or 2 days if the proheat - Webasto is run for cold weather, (not just for hot showers), or 6 hours of relaxing overnight sleeping with ac running.

I guess I am a glutton for punishment, But I Googled efficient alternator DC and found the 300 amp Alternator I tried. Worked good for 3 years so far but I have really cooked this thing at low rpms with limited airflow. (most efficient for power used according to the US grant sponsored report) Going Liquid cooled this time(easier to recapture, and control)  I agree, be gone the next day with on the road AC kicking and alternator recharging as we go to wherever we are headed.

I was looking for an inexpensive 24 volt alternator, but only found internally regulated intermittent duty cycle 25% rating at full listed capacity.. Not what I really needed.

Anyway, the key is the drive ratio on an inexpensive system. Set up properly, the rpm that the alternator makes power can be adjusted so as to not overload the engine. properly geared(belted) you are not overdriving(running to capacity) either unit.

Or a properly written logic that Responds with throttle control, and amp draw, voltage control to the field coils, will be the best for automated efficiency.

I have used rocks of various sizes to manually adjust my fuel consumption (hold open the throttle) and amp, as well as Air conditioning output.

Oh yea, you can also run it off of the oil you deep fry your turkey in. (just about the same amount of time passes for the amount of oil usedm (in generator) as turkey ate)

I should have run over to Bruces the other day when you came down. We have alot to talk about.

Catch you later

Bill

Quote from: boogiethecat on January 27, 2007, 06:37:10 PM
One thing you could do to make the alternators easier to find is use two 12 volt alternators and hook em in series, then hook them to groups 12 volt batteries in series to get your 24 volts. The "center tap" between the two alternators must be hooked to the "center tap" between the 12 volt banks.   One alternator would have to be mounted totally insulated, because it's frame is going to be at 12 volt potential.   Cheers

Good idea of charging each 12V bank independently in the 24V configuration. And the answer to the drive is V-belt
You are absolutely right that there are more choices on the 12V alternator approach. This would also provide a good source of power for the small Kubota starter.

Now, you've got to explain to me further why the 2nd alternator needs to be mounted totally insulated. If BOTH identical alternators are negative ground and mounted as such, how will the frame of the 2nd alternator be a 12 volt potential?
Is it because of the center tap connecting the NEG and POS posts?
If both (1st & 2nd) alternator mounts are insulated, would that make it the safest approach? Thanks.

Quote from: Homegrowndiesel on January 27, 2007, 07:06:21 PM
Well Ray,
Glad to hear from others that think the same way.
I should have run over to Bruces the other day when you came down. We have alot to talk about.
Catch you later

Bill,
I appreciate your input and I may have to pick your brains the next time I'm down at Bruce's.
I'm already in too deep that the only way out is success.
Ray

Ray, one alternator has to be isolated because it's frame is at +12 volt potential with respect to ground.
Here's a circuit:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.heartmagic.com%2Falternators.jpg&hash=d4f95d3a85448fc5fe7b10d20493cfcc1ad0b44b)
The alternators are hooked to the batteries with dedicated wires to avoid voltage sensing problems
during charging.
Cheers
Gary

Quote from: DrivingMissLazy on January 27, 2007, 07:15:59 PM
As long as you are not using the AC component to drive something that is frequency sensitive, you can operate an 1800 rpm alternator from 1250 rpm to 2250 rpm without any problem. The AC frequency will vary with rpm, but the voltage regulator will maintain the output within about 5 percent.

I am a "Home to Campground" kind of busnut and along the way when NOT plugged in, ALL my 110V-AC use will be through a Pure Sine Wave Inverter (eg: Xantrex SW4024) fed by a FAT battery bank, so all my sensitive electronic equipments will be humming happy.

And like Bill (Homegrowndiesel) said in his previous post: The key to this kind of project is "proper drive ratio".
I could be wrong but I understand this as: use the right size pulley/belt combination for correct/optimum rpm to the alternator.
Example. If the Kubota runs at oprimum  2000 rpm and the alternator runs optimally at 4-6000 rpm, then I am assuming that a 1:2 or 1:3 pulley rato will extract the optimum performance/s from both equipments.

Gary, thanks for the explanation on the 12 volt potential with a dual 12V alternator set-up.

Yes Ray
You got it, The hard part is the fine tuning on sizes of pulley ratios so as not to bog the engine down.
It is easy to run it wide open and make max power.

The problem comes when you have bulk charged your batteries, and you now want to run in economy mode (just off idle) to top off the batteries. The regulator is only calling for minimal field current and not drawing alot of power from the engine. When you turn on a large AC load (microwave, Hair dryer, etc) the regulator responds and stalls the engine, as the off idle power setting of the engine cannot handle the inrush current load.

The fix is to set the pulley ratio with a compromise. Each alternator has an RPM-AMP output curve. Match up the alternator RPM where it puts out, say for this engine 20 amps, now set the engine rpm at 1000-1200.  Now when the microwave gets used the battery gets used as the buffer, the engine still purrs away charging just as you had set it to do. If you find you need to speed up the charge or handle a larger load you can increase the RPM.

Electrically, with a solenoid, or manually with a throttle lever you can now controll how many amps the alternator is capable of putting out without overloading the engine.

Oh yea 1 more thing, I would go for the serpentine belt. Half the drag of a V belt. I found with the pulley setup I have (Not optimum dual V belts and large pulleys) the drad would not allow the engine to start when cold without loosening the belts.

I really like the idea of the 4 pole direct drive alternator with a bridge rectifier, Polar Power makes my favorite. I just find it hard to drop the 8 grand.

That engine you bought has a wide RPM range, I believe up to 3200 rpm, but makes awsome torque @1800 as well as minimum fuel use.

Go for the large frame oversized alternator, you wont have to worry about a backup as it will run forever not pushed to capacity as the smaller cheaper ones.

Good luck with your choices.

Bill

Another point-if you are running two alternators, mount them opposite of each other using to belts.  Then the tension from each alternator will cancel out each other to eliminate side thrusting.  But, I know on Kubotas made for belt drive, there outer bearing is bigger to compensate.

Powertech is making a stand by APU for trucks now.  It is a 2 cylinder Kubota or Caterpillar of 10 hp running at 2400rpm running a brushless 5000watt (derated to 5500 watt) 120v AC alternator.  Slick unit, only weighs 370lb (Including the Tundra 14,000btu A/C unit under the bed). 

My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  So for redundancy, run a 120v AC alternator since you will already have the big inverter that has the battery charging built into it.  Then you'll have two sources of AC power incase one quites.  You now have a 12v alternator on the engine and the small engine, but only one source for AC power.  With my idea, you will have an 12v alternator on the big engine (or 24v) and you could also have a small 12v alternator on the puttputt.  I just believe in redundancy.  To make the point, I have two 12v alternators on my bus (although I have the little 12v alternator disconnected on the gen since it was fighting with the inverter/charger), 120v generator and an inverter, three roof top A/C's with heat strips, two water heaters, two water pumps, two reefers, three heating systems (electric, propane, engine coolant driven).  Just my way- I KNOW you'll do it your way no matter what.  Good Luck, TomC

Quote from: TomC on January 28, 2007, 09:24:11 AM
My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  Good Luck, TomC

Right now, my bus is wired so that the important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator) are powered VIA a small modified sine Trace inverter/charger feeding off from a small bank of 24v house batteries. These house batteries are wired so that they are charged by the MCI's hefty 24v alternator (at the same time as the bus batteries) when running/travelling. The two banks are separated/connected by an "Isolator"

I want to improve my present renewable energy source/system by:
1) Increase the size of the house battery bank to at least 400-600Ah separated by an "isolator" from the bus 24V battery.
........Harness the excess DC energy produced by the stout MCI's alternator and save it into a larger house bank.
........This provides a lot of free AmpHours at the end of the days travel.
2) Upgrade to a pure sine wave 4k inverter/charger and charger to be used ONLY when hooked-up at a camp-ground.
........This inverter will be more than sufficient for all my 110AC needs from a fully charged 400-600Ah "house battery bank" when I get to a Walmart parking lot or a rest area after a whole day of driving.
.........The present modified sine Trace interter/charger that I now have will be the "back-up" inverter.
3) Develop a "Fast DC Charging" system for a 400-600Ah house battery bank
.........Used only IF and only when 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.
..........Such system should be housed in a noise reduction, vibration reduced enclosure

The peace, quiet and luxury of indulgence without the generator noise at the Walmart parking lot or any rest area is music to my ears. That's the reason for the system I am designing.

Quote from: gr8njt on January 28, 2007, 12:36:08 PM

Quote from: TomC on January 28, 2007, 09:24:11 AM
My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  Good Luck, TomC

Right now, my bus is wired so that the
important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator) are powered VIA a small modified sine Trace inverter/charger feeding off from a small bank of 24v house batteries. These house batteries are wired so that they are charged by the MCI's hefty 24v alternator (at the same time as the bus batteries) when running/travelling. The two banks are separated/connected by an "Isolator"

I want to improve my present renewable energy source/system by:
1) Increase the size of the house battery bank to at least 400-600Ah separated by an "isolator" from the bus 24V battery.
........Harness the excess DC energy produced by the stout MCI's alternator and save it into a larger house bank.
........This provides a lot of free AmpHours at the end of the days travel.
2) Upgrade to a pure sine wave 4k inverter/charger and charger to be used ONLY when hooked-up at a camp-ground.
........This inverter will be more than sufficient for all my 110AC needs from a fully charged 400-600Ah "house battery bank" when I get to a Walmart parking lot or a rest area after a whole day of driving.
.........The present modified sine Trace interter/charger that I now have will be the "back-up" inverter.
3) Develop a "Fast DC Charging" system for a 400-600Ah house battery bank
.........Used only IF and only when
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..
.........Such system should be housed in a noise reduction, vibration reduced enclosure

The peace, quiet and luxury of indulgence without the generator noise at the Walmart parking lot or any rest area is music to my ears. That's the reason for the system I am designing.

important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator)

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

Quote from: DrivingMissLazy on January 28, 2007, 01:01:31 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.

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

Quote from: DrivingMissLazy 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.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

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

Quote from: gr8njt on January 28, 2007, 06:13:22 PM

Quote from: DrivingMissLazy 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.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

Quote from: DrivingMissLazy on January 28, 2007, 07:16:13 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 (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. 

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 (http://theepicenter.com/tow123199.html)

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 :D  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!! :)

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

Quote from: HighTechRedneck on January 28, 2007, 07:40:43 PM

Quote from: DrivingMissLazy on January 28, 2007, 07:16:13 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).

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

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.  ???  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. ;D

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

Quote from: Don4107 on January 29, 2007, 12:54:19 AM
Does not really matter since the only reasonable way to charge batteries using rotational forces today is with an alternator. ;D

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......

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

Quote from: Don4107 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.  ???  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. ;D

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

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.

Quote from: gr8njt on January 29, 2007, 04:20:53 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.

Quote from: gr8njt on January 28, 2007, 06:13:22 PM

Quote from: DrivingMissLazy on January 28, 2007, 05:23:59 PM
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?  ;D  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.

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

Quote from: Stan on January 29, 2007, 06:26:40 AM
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.

Stan, you are absolutely right! You see, quite a few people DID NOT read the first post in its entirety or if they ever did, severely misinterpreted the whole premise of this thread!
Without sounding so redundant, my first sentence is:
..................."I have decided to use a DC (24V) generator vs AC in my bus conversion.
And at the end of the same post, there were a couple of questions:
..................."Does anybody have a personal experience with DC generators in general?"
..................."Any other options on the DC generators?" .....in reference to the G24/175 made by Ample power.
Without sounding arrogant,  I was NOT in search for a recommendation for a different way of power generating.
Remember the first sentence? It means I've made up my mind way before typing the first post of this thread.

The questions were directed at other Busnuts with personal experience on DC generating. I don't see any other interpretation to an otherwise very simple question.  Trust me, if I have the working design and schematic, I would be at a fabricator in a NY second and not begging for DC experiences here.

Since I pressumed "everyone knew" that I had already "decided" on the DC generator, I was also as honest on my hunt for the Busnuts with actual experiences on this project  who are willing to share their DC experiences.  Homegrowndiesel comes to mind who unselfishly and courageously stepped up to the plate and publicly posted his DC generating experience. I am very impressed with his set-up & success and I would welcome every opportunity to pick his brain apart or any other Busnut like him. I was not going to re-invent the wheel if I don't have to.  Makes sense?

However only one thing bothers me. The fact that some people get offended when their recommendation "to do it a different way" (like you said) and should go the AC genset route instead of DC" is not acknowledged, is bothersome.  I tried to be  diplomatic by not asking them to go back and read the first post in it's entirety. And as not to sound brash and abraisive, I avoided getting involved in the debate and argument on technical intricacies of micro-electric production which had no bearing on my project.

All I was looking for are some sensible answers to a few DC questions which HighTechRedneck so eloquently and intelligently answered.
His  #6 recomendation is "The golden rule" which I learned too late in a short period time I am a member of this board.
No wonder the folks that are doing similar project as this or interested in such a project are reluctant to respond and inquire publicly.
OK. I started this thread and I'll handle the brunt of the anger of the AC genset God. It's a shame people are ostracised for thinking outside the box in this forum.  But no worries, I will not make the posts of a few rotten coconuts destroy my high regard to the other helpfull members of this board.

I beg the moderators to close this thread as it has been degraded to a "Technical Bee".
I'll take HighTechRedneck's #6 suggestion seriously and discuss this project in private.

Hi;
    I have been using a DC generator that I found on E-bay a couple of years ago.  It was a
    communications generator that uses 32vdc.  I managed to reduce the volts via a load bank.
    Now I can dial in 28vdc on the pot on the regulator. Still tweaking the regulator and wire
    size.  Also used an automotive amp meter to see the amps being put out.  WOW - - - 60amps
    is neat to look at.  Just got back from three days in Quartzite AZ and the gen worked great.
                              Good luck.