| Author | Message | ||
| David Ljung Madison (Daveola)
Rating: |
So - I need a very large generator 12kW or more that I'll only need occasionally, and then for under 30 minutes a day. Trying to fit one of these on my MCI102A3 seems difficult, and the full gensets are over $5k. The thought has occured to me that I could hook up an alternator with a fan belt that I could attach/detach from the engine and use the detroit diesel on my bus as a power source. I *know* that this means idling my bus for 30 minutes or so each day, and that some people on this forum think that's a terrible idea. Those are *not* the people I'm hoping to hear from here. I'm not trying to start another "idling your bus is bad" discussion. I'm hoping to hear from people who might have ideas as to the logistics of making something like this work. I figure: 1) The full power of my diesel is 300HP. Generally an engine with "x" HP can power "x/2" Watts of power. So, even if my idle HP is much less, I can still easily push a 15kW alternator. Does anyone know what the idle HP is? 2) Has anyone actually tried either this or running something else by belt off the engine? 3) Any thoughts on how I can make a belt system that can connect/disconnect to the engine (so as to avoid drag when I'm driving and don't need the alternator power?) I've already removed the toilet and A/C compressor from the right of the engine, so I'm figuring that would be a good place to put something like this. Thoughts? | ||
| John MC9 Rating: N/A |
well... Utilizing the air cylinder from the radiator fanbelt array of any MCI product, would net you the device needed to power the devices you wish to run from the main drive pulley of the engine. You would have to add an electronic solenoid to control the air supply to the air cylinder, but that's an easy find. All that..... would take care of tightening the belt (at will) that will drive your alternator! We idled the bus for hours on end, during charters. Have no fear. | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Im sure you can make it work. 'twere me I'd belt drive the generator through some sort of clutch or means of disengagement (maybe even a PTO off the tranny if there is one) and set it up to give you 60hz at about 1000 engine RPM. Then I'd get myself an electronic governor for about $400 (or less if you watch ebay) from Woodward and use it to take control of the engine throttle... it would be pretty simple and you'd get exactly 60hz no matter what the load. You could certainly try lower RPMs, I'm sure it would also work. With the electronic governor running the show, you have almost complete freedom of pully ratios and no problem with stability and/or frequency accuracy. FWIW your 12kw will only take about 25 horsepower. My guess is that with some research you could probably find a 12 volt operated clutch that would pull 25 horsepower pretty easily. Fan clutches will carry 10-15hp, stump grinders use 25hp clutches, and I bet even bigger ones are stock in the right industries... It's even possible that the clutch on your ex- A/C compressor is big enough... just a thought... Check these guys, and there are loads of similar companies out there http://www.ogura-clutch.com Have fun... | ||
| David Hartley (Drdave)
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Uh.. What is it that only needs power for 30 minutes? Couldn't be for charging inverter batteries as they take much longer to charge unless you are only spinning up a 20,000 pound flywheel dynamo..Or a gigawatt laser power capacitor bank... Hmmm... Buy the generator, You will be much happier and it will be a lot more cost effective. Hey after all you spent the big bucks on the coach what's to save now??? | ||
| Craig (Ceieio)
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Hmm, looking at gensets in the 15KW range, it looks like you could budget about 30 HP for the generator. 15KW is a little more than twice of what the big honkin' 270A, 24V bus alternators put out. Take a look at the belt arrangement and tensioners for that as a starting place for mechanical design. I think the next thing you would need to decide is if you are going to use the normal or fast idle settings. Then pick a generator head (most likely 1800 or 3600 RPM). Once you figure that out you can figure out the pulley ratios to get the gen head speed to the right RPM. I think the fast idle might be a better choice to work from as, it is a tad easier on the engine, and the rpm will likely stay better regulated at the gen head (more on this later). Depending on what you get, varying the RPM will vary the AC frequency, and the output voltage, so you want to stay as steady as possible on the RPM. Back to RPM variations. Lets say you have a 3600 RPM gen head (cheapest usually). To make the math easy, lets say the bus idles at 800 RPM. This means that you will need to gear the engine speed up by 4.5 times to make 3600 RPM. If you get a 50 RPM variation (due to rolling idle, varying load, whatever) the gen head will vary by 225 RPM. If you ran the engine at 1200 RPM (again for math's sake) then you have a 3 to one gain and a 50 RPM gain would be 150 RPM variation, and, in my quite unprofessional opinion, less likely to occur at this engine speed. Depending on what you power, the variations in RPM will or won't matter. If it really matters, going to an 1800 RPM head and a fast idle (with my made up idle numbers) would drop a 50 RPM engine variation to a head variation of 75 RPM. I made up the numbers here, but you get the idea. You can make some real work measurements and do your own math, based upon what matters to you. Good luck! Craig - MC7 Oregon | ||
| RJ Long (Rjlong)
Rating: N/A |
Interesting idea, Daveola. . . Dave Hartley asks a good question, and I'd like to follow his with how did you come up with the 12kw or more requirement? Are you planning on an all-electric coach? Not "naysaying" here at all, just asking so that we can better assist you. BTW, have you talked to Dick Wright at Wirco? | ||
| David Ljung Madison (Daveola)
Rating: N/A |
To clarify: 1) I don't need a generator head, I need an alternator, because I need DC, not AC current. That makes the RPM calculations moot. 2) The alternator on the bus is very small wattage because it doesn't need to be any bigger. 3) Yes, I am charging batteries, and yes they can take it that fast. I'm not going to have one or two T-105s on this bus, I'm going to have about 33kWh of batteries. Yes, you read that right. Before telling me that the bus can't carry that weight or that I can't charge the batteries that fast, please do the calcs, and first visit: http://bus.getdave.com/Infrastructure/Electrical/ The intent is to get solar with that $5k instead of a genset, and then I only need the alternator charge occasionally, maybe 1 hour one day, and not at all for the next three. And no, I'm not interested in running a smaller genset for longer periods of time. And finally, RJ, who is Dick Wright and what is Wirco? I see they make baskets? <soapbox> I notice that just about everytime a question is posted to this board, about half of the people respond not with answers, but with suggestions that are different than what the poster is asking for. It's a bit frustrating. I know that I'll see it more because what I'm planning is unorthodox, but that doesn't make it impossible, nor does it make it undesirable for *me*.  </soapbox> | ||
| FAST FRED Rating: N/A |
All the usual cautions of damage from prolonged ideling would apply. When turning a 30 to 60HP factory air cond setup for cooling at hi idle the engine life is reduced . And I dont think your alt will pull 30 hp. A disposeable gen set , used OTR reefer 2 or 3 cylinder Yanmar or Kubota , a bus alternator and a smart regulator would do even better as a big batt charger. The advantage is generator speed would be detirmined by amps required , so the as the batts begin their long charge cycle the noise and fuel consumption will be greatly reduced. FAST FRED | ||
| David Hartley (Drdave)
Rating: N/A |
I wasn't trying to burst you bubble.. It's not that it can't be done. It's more like if you throw enough money at it almost anything can be done. Your calculations of energy needs and supply are "if it was a perfect world", Sorry but things don't always work out that way. For solar you need a "LOT" of roof real-estate for panels. A typical bus roof doesn't have that kind of space. Typically only about 600 watts of solar will take up every square inch of roof. or approximately 30 to 50 amps capacity on a perfect day if the sun is directly overhead. I would suggest that you get a solar energy engineering company to design the system. In the Real world, The inverters that you would really need would cost from $2,000 to $4,000 each. Just to start-run and carry the a/c system loads. The xantrex RS3000 units would work as would the Outback stackable grid-tie units. A guestimate on the battery weight would be in excess of 2,400 lbs or more. for instance fork lift battery packs weigh 2,200 to 3,500 lbs each. for the 36 and 48 volt versions. But if you plan on using things like the 8D size Lifeline maintenance-free @ 210 a/h each you would need probably 10 or more up to 20 of them. You can't rapid charge them in an hour either! and then at an estimated $360 each you are starting at $3,600 or more for the first 10.... Doable maybe/yes, Financially feasable - NO . Electrically and Mechanically - A tough job... Why not just buy a 12 kw fuel cell or one of the european stirling power units which are about the size of a dishwasher and a large LP tank? I would rather spend the 7 to 15 dollars a day on diesel fuel to make power when I need it than spend $30,000 for a magical FREE electricity system that could melt down in a heartbeat. Keep Dreaming Anyway... | ||
| Stan Rating: N/A |
Just to clear up a little bit of terminology. A generator produces DC. An alternator produces AC. An automotive alternator has internal diodes that convert the AC to DC. | ||
| John MC9 Rating: N/A |
David - If you re-read your initial post, you'll see where you went wrong, and why the topic drifted. The simple version: "I need a very large generator 12kW or more that I'll only need occasionally, and then for under 30 minutes a day I could [instead] hook up an alternator with a fan belt that I could attach/detach from the engine that this means idling my bus for 30 minutes or so each day" But you then added: "I can still easily push a 15kW alternator. " Dave, if all you want to do, is run air conditioner(s), and use a few electric appliances while the engine's running, all you'll need is a Trace 4024 and a modest bank of batteries. I don't understand where the need for a "15kW alternator" fits into this...? If you plan to use 12v, you can add another alternator equivalent to the size of the 24v bus one, and run that from pulleys (you didn't say what voltage your bus was). If your electric needs are as you stated: "occasionally, and then for under 30 minutes a day", it really doesn't take too much to supply that, and putting a model together as you first suggested, seems perfectly doable to me. If on the other foot (after reading your website), you want to run amplifiers using "400 watts" of energy, and a bunch of power hungry appliances, from a battery bank that you say will be: "about 33kWh of batteries", well....... Even if it were feasible, it ain't gonna' be practical. And the first dead cell or loose battery clamp, in that massive battery array is going to make you wish you bought a Winnebago. Try to picture yourself crawling over the batteries to fix a clamp, add water, or replace one.... You asked for advice and suggestions (re: "Thoughts?") The guys here are trying to give you their thoughts, and it looks to me, that they took some time to think about what they're offering to you for their thoughts. It didn't drift off to "don't idle you engine", at all! They're trying to save you time, effort, and grief. But you sound like me....And I'll bet you're going to try to figure a way to do it anyway. I spent two weeks trying to figure out how to mount the AC units on top of the existing roof hatches, ignoring all the advice I asked for here. A neighbor busnut tried it , and the idea worked, but needs so much tweaking, that I decided to do it the way the guys here suggested. It went quick and easy and required no tweaking at all. "Do it your way", but don't cast the suggestions you get here, aside too carelessly. These guys took time out of their own day to give you their thoughts... Just as requested. Cheers, man! And good luck with it all, regardless! | ||
| Tim Hoskinson (Tdh37514151)
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Hi David I am curious as to what kind of battery you are going to use. I am not picking on your idea I really like the idea but in 29 years of working in all types of electronic repair and design I have not been exposed to a battery that will give long term discharge, short term charge and five years of battery life. If you would please let me know where this battery is available I would like to check out its specifications. Thanks. Tim | ||
| Dale Hendricks
Rating: N/A |
You might look at some of the military auction sites. They sell 28 volt generators from time to time that might meet your needs. Prices are generally pretty reasonable since not much use for them in house or commercial markets. | ||
| Gary Stadler (Boogiethecat)
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Tim, Maybe he's hooked up with someone in Toshiba for his batteries. Things are certainly about to change in a short time... check this... click here | ||
| RJ Long (Rjlong)
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Daveola - Thanks for the link regarding your electrical plans, very interesting reading (as is a LOT of other things on "GetDave"! ) Dick Wright of Wirco is the west coast's leading genset guru. Has probably forgotten more about RV applications than we'll ever know. May not be the least expensive, but it will be right for the application. http://www.generatorman.com/ is his website. You might also want to contact Ian Woofenden, the Senior Editor of Home Power magazine, a publication geared toward those who like to live "off-grid". Ian also owns a bus, so he can really share real world experience with you. http://www.homepower.com is his website. As a side note, ever notice that whenever Glenn Miller's "In The Mood" is played, people have a very hard time resisting the urge to dance? HTH, RJ PD4106-2784 Fresno CA | ||
| RJ Long (Rjlong)
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While re-reading this entire thread, another thought just crossed my mind that hasn't been mentioned yet: A little Kubota genset, even if it's 15kW, will burn a lot less diesel/hr than that big old Detroit. At $2.65+ per gallon and most likely going higher, a consideration. . . Where were you planning on putting the genset? (Most folk, btw, shoehorn it into the old A/C condensor compartment behind the LF wheel.) Your posts have certainly gotten the creative juices (and resulting opinions) flowing!! HTH, RJ | ||
| TomNPat
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David, Thanks for a refreshing look from a different perspective. Lots of us are running down the road charging our batteries with the engine now. So your approach isn't without basis. What you can really do to help us out here is to try your ideas and let us know the outcome, what works, and what doesn't. Too often we see novel ideas but never hear about them again. Looking forward to your posting 'THE REST OF THE STORY' based on your results. TomNPat | ||
| Richard Bowyer (Drivingmisslazy)
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Sounds like a good idea. I suggest you use another 270 amp alternator like you have and run them in parallel. It takes a lot of work and money to convert an existing 120/240 volt 60 hertz AC alternator to a 24 volt DC alternator. Plan on running the engine at a sufficient rpm that the alternators will produce maximum output. I would guess 1000-1200 rpm. Richard | ||
| niles steckbauer (Niles500)
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David - just read your 'electrical system' - if you are total electric you left out stuff like HWH, and any southern use of the A/C system will result in KWH usage of a factor of 3 to 5 times your figures, per unit. You state that you want to draw your batts down to 50% and recharge them twice a day but never bringing them up to 100%. Battery life can be affected by multiple variables, overdischarging your batts or keeping them partially discharged will shorten their life span, batteries have "memory" and are best charged to their memory level which is usually close to 100%, and a battery has a limitied number of charge cycles in its useful life that would severely factor into your twice a day bulk charges. I understand that you plan on doing Solar (eventually?) but an array area equal to the size of your roof would not maintain the usage you are proposing much less top off the batts. Not trying to be a kill joy - and I too dream of being off grid - but when you "do the 'actual' math" it don't work unless your willing to put out six figures worth of benjamin's for state of the art components. FWIW - Niles | ||
| Tim Hoskinson (Tdh37514151)
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Hey Gary thats pretty neat I had not seen that befor. It looks like it is on the way soon. Wile I'm shure it will come I am also shure that at least in the early days it will be very expensive. But at some point maybe some of the dc power problems we all are faced with will be minumized. Tim | ||
| David Ljung Madison (Daveola)
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Sorry about the alternator/generator/genset confusion. Yes, a generator produces DC, and most vehicles actually charge batteries with an alternator with rectifiers. Chances are that I would be using something like that. Does anyone know what the approximate idle fuel consumption and idle HP of a 6V92 is? And has anyone ever hooked a clutch up to the power output? What's a PTO? There's also the option of using an air solenoid to stretch a belt like the radiator fans. I've noticed that when the radiator fan belt isn't stretched, the fans are still turning - are they just turning slower? And if so, how come the belt slippage doesn't wear down the belt significantly? | ||
| David Ljung Madison (Daveola)
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Hartley: 1) I can fit 1kW of panels on 2/3 of the roof of my bus. Yes, I know how much power output that actually gives. 2) Yes, I know how much the inverters cost. 3) Battery weight, about 1800 pounds. Yes, I know how much they cost. John MC9: The electric needs I have for "under 30 minutes a day" are extra charging to compensate for what the solar panels can't manage. Yes, somedays it will be longer, and some days I won't need it at all. I'm figuring an average of 30 minutes a day since I needed 1-2 hours a day with an 8kW genset. Hoskinson: HUP Solar Ones RJ: Yes, In The Mood certainly gets people dancing RJ: Good point on idling fuel, if I can't use the full HP of the idle engine, then I'll be wasting fuel, however I am converting the bus engine to veggie oil, so that's less of an issue: http://bus.getdave.com/Infrastructure/Vegetable-Oil/ TomNPat: Thanks. I am planning on trying it out and posting everything. Niles500: Not total electric. I'll be using propane for water and bus heat. And yes, I've done the battery life calculations. | ||
| David (Davidinwilmnc)
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Daveola, I guess another point/issue is the noise involved. I assume you have a 6v92 or 8v92. I have neither; I have an 8v71 and it's loud. I can't imagine listening to that thing run to charge batteries. Of course, maybe where you'll be doing this the noise will be ok. The smell could also be a problem. How about a smallish genset. Hooked to a decent inverter/ charger with a generator start circuit and a good bank of batteries, you should be set. You'd also have some redundancy; you'd have a generator, battery bank, and bus alternator all supplying power. I know truckers aren't allowed extended idling in many places; are conversion owners? That could be a problem too. | ||
| motorcoach1 Rating: N/A |
there use to be a company called Aotogen that made generators for the marine market , don't know if their in biz anymore but have installed them years ago and with great results. This just bolts on any engine and operates at any speed | ||
| motorcoach1 Rating: N/A |
you may want to look around in industrial junk yards for a Reeves drive, there variable pitch and you set thr RPM and if the motor fluctuates the drive keeps output RPM's constant | ||
| niles steckbauer (Niles500)
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David - since no one has answered you yet - a PTO is a 'power take off' - a shaft driven by the mill but not necessarily the 'drive' shaft that powers any number of components hooked to it at the approximate operating rpm of high or low idle of a diesel - think of any number of implements towed behind, and powered by, a farm tractor - HTH -Niles | ||
| David Ljung Madison (Daveola)
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Thank you for all the suggestions regarding RPM, but please realize that for this application RPM is not an issue since I want DC output, not AC. I'd be setting the 6V92 to whatever speed would output the HP that I needed. Niles500: Where would the PTO be? How do I figure if I've got one? It's an MCI102A3. | ||
| RJ Long (Rjlong)
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No PTO on a MCI 102A3, sorry. | ||
| John MC9 Rating: N/A |
David - It wouldn't be all that difficult to add a pulley to drive another belt, regardless of engine configuration. And generating DC is easy, no rpm to be concerned with. You're mind is in the right direction but the task overwhelms the practicability. You simply will not be able to generate the amount of power you're thinking of, without some major expenditures. Is it really worth it? For what? To say you did it? Anything in this world is possible to do, bar none. And I truly believe you can do this task. But, in my opinion, you'll be a lot richer, and further towards your goal of being travel worthy and on the road, if you abandon the idea of doing what no other has bothered with, and just follow the crowd. Propane is easy, plentiful and inexpensive, generators are foolproof, and a simple inverter can power the important appliances off-line. Being a Don Quixote? Does it really pay? | ||
| David Ljung Madison (Daveola)
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I can't generate 15kW or so of power? If I can't get 30HP out of my engine then there's something seriously wrong with my bus. And as far as being a Don Quixote, your argument, if truly applied to all of us, would require selling all of our buses and living like normal people. | ||
| Tom Caffrey (Pvcces)
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David, if you try to get 30 hp out of a fan belt, it may not last very long. There are formulae that will help you calculate what will be required in belts. I think that for fuel economy, you will want as low idle speed as you are able to get the charge rate you are after, adjusted upwards a bit to make it easier on the engine, if needed. Somebody reported the fuel consumption of his bus with an 8V92 at 1050 or 1100 RPM as being 3 gallons per hour. The 8V71 or 6V92 might be appreciably lower, but dropping the RPM to under 1000 will probably help. We do the equivalent by using a 105 hp Isuzu for 80 amps at 32 volts for battery charging on our boat. We do this at a dead idle to keep the engine warm enough. It's not ideal, but it works well enough. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| FAST FRED Rating: N/A |
Considering the added drive setup to spin a second alternator at an RPM needed to get output at idle (where youre engine is suffering with about 5psi of oil pressure , and operating way overcooled and undertemp) would cost more than a used diesel . I still dont undrestand why a few hundred for a running takeout , a used coach alt , and a smart (yes$200) V regulator is dismissed. $5000 for 6KW is hardly everyones dream, but 250A of 24VDC for under a grand sounds OK to me. With an engine running at proper temps the unit could be used for Co generation. Creating endless hot water or coach heat or engine pre heat is only a fistfull of plumbing . FAST FRED | ||
| David Ljung Madison (Daveola)
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Tom: It seems that I should be able to get a belt to handle 30HP since I've seen 15kW gensets that are belt driven, but I may be wrong - any idea where I can find those formulae you speak of? Fast Fred: I do *not* care about RPM because I need DC not AC. If idle is hard on the engine, than what speed would be best? And what's a "running takeout"? I've thought of using gen heat for water heat, but I intend to use my genset *very* little, and I"m going to have a flash water heater, and it doesn't seem that they'd combine very well. | ||
| motorcoach1 Rating: N/A |
david look at a welding supply house for 400 amp diodes or bigger and build a rectafier just remember that DC amps are more than AC amps so as not to burn up your 4 pole altrenator this will make eveyting the genset puts out DC and thats a lot of amp power you could weld with it LOL remember all alternators are AC and changed to DC by the Diodes and generators were built AC and DC without the Diode. but all AC gensets can be turned into DC outputs. | ||
| motorcoach1 Rating: N/A |
oh by the way train engines run on a altrenator and supplys elictric to the motors you may want to look up GE's power system.mmm works for them | ||
| Stan Rating: N/A |
Motorcoach: Are you sure about GE's train system? I used to work on electric drilling rig controls. The motors were GE locomotive DC motors and the generators that drove them were also DC with field control. Companies other than GE did supply systems that were alternators driving similar DC motors through SCR pulse width control systems. | ||
| Bill Glenn
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Hey Daveola, Lots of good experience and opinions weighing in here. Some negative, some positive. Lots of good discussion none the less. Thoughts? OK! I like your basic thought process. I think the comments about noise, and fuel comsumption are important. Please do not discount the advice about RPM. The DC alternator needs to spin at the proper RPM at the desired engine RPM. My used (take out) kubota 18hp diesel drives an Ecoair 300 amp DC alternator with 2 standard v belts. ( they claim 5.5 hp draw @ 305 amps) This drives the alternator and an ac compressor mechanically in their proper RPMs, well almost. I should have dropped the engine pulley down to 9" to not overload the engine @ low RPMs as Full 300 amp on 1000 engine rpm will result in a stall condition. I manually increase the RPM of the engine when large loads are needed, and reduce it to a loaded idle (1000 RPM) when drawing less than 200 amps. With a smart controller I could regulate the fuel rack to increase the RPM when large Amp draws occour, therefore maximising the available amp output to fuel use. I need to install a solenoid to increase the RPM when I engage the AC clutch, or on large charge conditions. Proper pulley ratios (RPMs) are important. MY Harley uses 1 cog belt more efficiently. I run the kubota on WVO also. I also drive a 10 cu. in. york AC compressor off of the same 10" engine pulley. (up to 5 tons ac, and freezer holding plate) Better efficiency to direct drive the AC compressor than mechanical to electrical then electrical to mechanical compressor. No need for propane most of the time for hot water, bus heat, and detroit preheat. Cogeneration works. I use 6 L16s, 415 ah 6 volt batteries @ 12 volt for about 600 ah usable till recharge. Can go about 3 days without starting generator without using Air Cond.(DC frige, coffee maker, microwave, computer, lights, etc) Bulk charging @ 300 amps brings batteries up pretty quick but I have yet to install my solar panels to top off my batteries, therefore the last 20% of charge takes hours. So far no problem for me as we seldom sit still for longer than that and we charge the last 20 % on the road with the bus alt. WOW I have got to get some of those Toshiba batteries as well as one of those DC Air Cond. units. The road less traveled is usually bumpy and not as quick, but it is your trip. Keep up the good thinking. It would be hard to pull my bus with horses, or chat with all of these inteligent people via pigeons. Good luck with your choices, keep asking questions, and threshing. Bill Glenn | ||
| John MC9 Rating: N/A |
"It would be hard to pull my bus with horses, or chat with all of these inteligent people via pigeons." Egads, that's profound, ehh David? FWIW | ||
| Tom Caffrey (Pvcces)
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David, a belt supplier should be able to furnish the information you need. I hadn't thought about a cog belt; they seem to be pretty reliable. To determine the minimum rpm to run the engine, look at rack position. You should get pretty good results by picking up the engine speed enough to bring the rack back to around 50%. With some experimenting, you will find a combination that you like. Just avoid extremes. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| niles steckbauer (Niles500)
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I'll shut up and yield to Bill Glenn - No one on this board has spent as much time standing at the rear of his bus "teaching" people about "new" technology (that he developed) than him - but I'll still say you have to have his capabilities or pay (in time or money) for the technology he has developed - thanks for sharing Bill - niles | ||
| FAST FRED Rating: N/A |
Sounds like the setup Bill Glenn has working could be used by most folks . For those that need air cond 24/7 the small Kubotas are EZ to feed . For folks with out that need , esp with a propane fridge , the "Quiet Time" could last a week or more! Sounds like the future for many campers, FAST FRED | ||
| David Ljung Madison (Daveola)
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I know that a DC generator needs to be within a reasonable RPM range, but this doesn't need to be "locked" to a specific RPM range like an AC alternator, especially if my load is fairly constant, which it will be. Btw, you mention 300A, but how many volts? "It would be hard to pull my bus with horses,.." Thank goodness that's not what I'm trying to do. Don't even know how I'd set those pulleys up. ;) | ||
| Cory Dane Rating: N/A |
I played with that idea, use the engine for a gen-set. They used a diesel, A BIG ONE, at work for an Emergency Generator but the Genset was HUGE! If the Air con can't keep the engine busy enough to run efficiently, I don't know if you can come up with enough load to make a genset do it. One of my thoughts was to put a dc gen on the power take off of the tranny, where the air con used to be. but seems the engine is too darn big for that also, it will just idle, even fast idle for my 8V71N really isnt loaded enough. I keep thinking about it, maybe someday???? dunn no. Have to get the engine running again first lol. CDane | ||
| Richard Bowyer (Drivingmisslazy)
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Everybody should understands that just hooking up a set of diodes to an alternator is only solving part of the problem. A standard AC alternators output voltage will be much too high to use for a DC supply. You must include a step down AC transformer to reduce the voltage to the appropriate voltage. And the AC alternator should really be three phase to reduce the AC ripple on the DC output. And the output AC frequency should be much higher than 60 hertz, to reduce the size of the alternator and also to reduce the AC ripple. And it goes on and on. And you can get drive belts for any hp you desire. I have build dozens of large belt driven machines using 500-750 HP motors driving 50 hertz alternators in the 500 KW range. Richard | ||
| Bill Glenn Rating: N/A |
Hey David 12 volt At present I am set up for 12 volts. You are right about not needing an exact rpm, just minimum ( to charge desired amps) and maximum (rated max continuous). With a standard alternator (or 2) I think you will need an overdrive belt ratio of 2.5 to 1. to get adequate amp output, based on about 1000 rpm of engine. when you find an alternator of that size look at the min-max output graph specs to properly size. Thanks for the kind words guys. Richard you brought up a couple of good points. Please explain, By increasing the hertz we can reduce the alternator size? I understand that 12volt 300amp would be equal to 120volt 30 amp (watts) Thinner wire same power, smaller. Still looking for smaller better etc. New hybrid cars run 100-320volts, with suitcase style battery packs. New grid tie solar charge inverters run between 24-320 volts dc. Now if we use those Toshiba Batteries?????? Quick charge, small wires, utility grade 120-240 volt ac, capable of hooking to the grid Plug-n-play? Do the diodes clip off the power from the top of one waveform to the bottom of the other? Efficiently (heat is the waste I think) Can we clip off 1/2 & 1/2 and double the dc pulses. Top part of the waveform, and bottom part of the waveform? Always trying to learn more. Thanks in advance for the info. David,Good luck with your choices and keep us informed. I more thing, not much drag on engine when field isn't calling for charge. Bill Glenn | ||
| FAST FRED Rating: N/A |
The big problem with an all DC setup is most folks have carbunkles on their roofs for cheap aircond. While the units can easily be run with an inverter , its about a $4000 24V Trace or its equal that is required. IF DC air cond was use , there is still the need of a battery charger , large enough to run the airs , as well as the usual house loads , and charge the batts. That $4000 Trace again fits the bill with 100A of DC when on the Power Pole. Unfortunatly the low cost and great fuel consumption of pure DC charging (great for the bat set too) can be lost in the rest of the setup. FAST FRED | ||
| Cory Dane Rating: N/A |
I agree with FF Generating AC from the engine just creates too much cost and problems; Generating DC to the INVERTER is just the ticket. Some kind of load control is needed to run the engine but the hook up is simple to the coach battery and the INVERTER supplies the power as SineWave AC. It doe not make sense to reinvent the wheel here. All that you will do is add cost to your conversion and there is no gurantee you will like what you end up with or that it will work as you expected. Keep it simple and the problems will remain simple. You start messing around with frequencies of AC and you are now getting into cost and technology that is unheard of in any motorhome. DC to Sinewave 60cy, how simple is that. Ok, that is a bit oversimplified but to compound the problems makes no sense, and then think about resale. Will the next guy have any idea what you added to the coach much less be able to repair it? If he thinks the addition is bogus, the value will drop. You need to KISS it for any resale value. A nice 24vDC gen on the power take off, or engine pulley,hooked to a regulator and feeding the coach batteries which are supplying a nice trace 2465 Sinewave will do a marvelous job. complicating this scenario makes the added risk of a failure a very real hazard. Sometimes you really need to take a second look at that DO IT YOUR WAY theory and give it a second thought and perhaps change it to doing it the best way instead. cdane | ||
| Stan Rating: N/A |
David: Ordinary automotive alternators already incorporate all the questions you ask. They are three phase, high frequency with full wave three phase bridge rectifiers. Until someone invents a diode with no forward voltage drop, we can't improve much on efficiency and heat generated. I am speaking from a practical point of view so please don't start an argument about using class 7 bearings and exotic materials to reduce friction and lower resistance. | ||
| David Ljung Madison (Daveola)
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I think that somehow people have lost my message. FF and Cory: I *never* wanted to run AC 60cycles off of my engine. I want DC. I've always wanted DC. Cory, you are describing exactly what I asked at the top of this post. Again, my plan is explained clearly at: http://bus.getdave.com/Infrastructure/Electrical/ Stan: You are replying to Bill, not I. I had no question about how automotive alternators create DC. I hope this is clear enough: Does anyone have any experience with generating DC charging off of the diesel engine that comes with their bus? I have some useful suggestions so far here, so thanks for that. If anyone has actual done this or has ideas of how to do it, I'd love to hear it! Thanks! | ||
| Richard Bowyer (Drivingmisslazy)
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DC generators have not been utilized, or manufactured, for many years for the applications you are talking about. One of the biggest dis-advantages of a generator that actually generates DC directly is that heavy duty brushes, capable of carrying the full output amperage and heavy duty commutator bars (not slip rings) are also required. The wear factor and failure rate is extremely high on this type system and that is why they are no longer utilized in automotive applications. In fact I can not think of a single application where DC generators are still utilized. I do not think you can still buy a DC welder that uses a DC generator as used to be available. To the best of my knowledge, all DC sources consists of an AC device of some type that is rectified to DC. To answer one question about frequency (hertz), a 400 hertz alternator is about one fourth the size and weight of a similar rated output alternator designed to produce 60 hertz. Quite truthfully I have forgotten what the output frequency of an automotive alternator is but I suspect it may be 800-1000 hertz or higher. The higher the frequency, the easier it is to filter out the AC ripple and end up with a much purer DC output. The one advantage of a DC generator is that the DC output is very pure and old time welders were unwilling to switch over to the AC to DC devices because the welds were not as nice. Richard | ||
| Richard Bowyer (Drivingmisslazy)
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snip "Do the diodes clip off the power from the top of one waveform to the bottom of the other" Sorry, I forgot to answer this question. Yes, half wave rectifier only converts the top half of the AC sine wave to DC. It is a very poor DC with lots of AC ripple on the DC and for example, this AC ripple is what you hear as hum in an audio amplifier or other similar device. The next best type of rectification to DC is called full wave. It flips the bottom half of the sine wave up to be beside the top half and is a significant improvement in the DC output. The next upgrade is a full wave three phase bridge rectifier. It takes all three phases and flips the bottom half of the three sine waves up to the top and these pulses all over lap and provide the best DC output. DC is typically rated in the amount of AC ripple that is riding on the top of the DC and the lower the ripple, the better quality the DC is and for example, the lowest hum in an audio amplifier. I have also heard of six phase power to be rectified to DC and as I stated previously, the higher the AC frequency, the better the quality of the DC. Probably more than some of you wanted to know, but now I have said it and I should not have to repeat it anytime soon. Richard And no, I am not a degreed engineer. | ||
| David Ljung Madison (Daveola)
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1) AC 60 cycles alternator - needs RPM matching 2) DC generator 3) Alternator -> rectifier -> voltage regulator creates DC output I am *not* and have *never been* interested in #1 or #2. I am planning on using #3 if I can figure out how to make it work. | ||
| Richard Bowyer (Drivingmisslazy)
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David, the only difference between #1 and #3 is the rectifier. For DC there is no RPM matching required. #3 is typically a 60 cycle alternator with a rectifier and voltage regulator. A four pole alternator would output 60 hertz at 1800 rpm. It will output AC voltage from around 1200 rpm (40 hertz approximately) to around 2250 rpm (75 hertz approximately). More better would be a higher frequency alternator and a multi-phase output, but that is all there is. Richard | ||
| CoryDane Rating: N/A |
(((( I am planning on using #3 if I can figure out how to make it work.))) I guess I am missing something here. ((( 3) Alternator -> rectifier -> voltage regulator creates DC output )))) This is current technology for cars and trucks. whats the problem you are trying to solve? (((( 1) The full power of my diesel is 300HP. Generally an engine with "x" HP can power "x/2" Watts of power. So, even if my idle HP is much less, I can still easily push a 15kW alternator. Does anyone know what the idle HP is?)))) My 8V71N is 300hp. I didn't look at the manual but I think idle is about 1000rpm. (((( 2) Has anyone actually tried either this or running something else by belt off the engine?)))) took the air con off the power take off. the air con died. Spoke with a few that had a generator on it in place of the AC. No comment on idle generation from them. Have actually theorized the same think you are thinking of, but why can't you use the engines generator? It is always in the picture anyway. (((( 3) Any thoughts on how I can make a belt system that can connect/disconnect to the engine (so as to avoid drag when I'm driving and don't need the alternator power?)))) how about an electric clutch? Air conditioners for cars have utilized this for years. I thought the gensets stop producing (less drag) when the voltage is up? Take most the load off and the gen/ac alt will stop producing, thus less drag. With that thought, YOU COULD leave the engine gen on the bus battery and the added gen on the coach battery??? Some of the machinery places sell larger generators w/o the motors, may fit nicely to your idea. But to keep it simple, it needs to put out DC, one way or the other. How will you switch between the engine gen and your add-on gen? getting farther from the KISS theorum. Switch added gen off and bus gen on to the coach battery when traveling??? sounds like a couple of really big switches or solenoids and how would you switch them? Sounds like it needs to be manually switched. In my eyes view, Pretty much ANYTHING can be done, providing the funding available, question is, how far do you want to go. CDane | ||
| David Ljung Madison (Daveola)
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"#3 is typically a 60 cycle alternator..." That's not true. Automotive alternators run at a hertz dependent upon the RPMs and the belt. And it doesn't really matter what hertz that is as long as you're getting the power output you need. If I had to RPM match my car engine so that my automotive alternator was running at 60Hz, I'd have a damn hard time driving. Anyways, please, for the last time: I care about DC output. I don't care about 60HZ anything. I am going to use an alternator/rectifier to create DC output, like a car alternator but much bigger. I don't care what frequency it runs at. I am simply going to set the engine speed at a balance between fuel usage and running the load of the alternator. Let's call this a "reasonable idle." The reasonable idle will be fairly constant, because the load is fairly constant. I do not need complex fuel delivery control because of this. ALL I need is a belt, an alternator/rectifier/voltage regulator, and some way to attach/release the belt from the engine. Bill mentioned that there isn't much load when the field isn't calling for charge. Can I run a monster alternator off the engine with the outputs disconnected and not put much load on the engine? Maybe someone should start a thread that discusses 60Hz, RPM matching, AC output, and all these other topics that aren't relevant to the question I originally posted?? | ||
| David Ljung Madison (Daveola)
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(((This is current technology for cars and trucks))) Exactly! The problem I am trying to solve is mounting a *second* alternator that is used intermittently. It will power the coach batteries instead of the bus batteries, and it will be much bigger (like 600A). (((YOU COULD leave the engine gen on the bus battery and the added gen on the coach battery???))) Yes!! (((How will you switch between the engine gen and your add-on gen?))) Why do I need to switch? The engine gen does the bus batteries, my gen does the coach batteries, if it's connected/clutched/attached/whatever. (((getting farther from the KISS theorum))) This seems much simpler than having another *engine* installed that is hooked up to a 60Hz alternator that has an auto-start and it's own fuel lines, exhaust, cooling, etc.. etc.. Besides, I can fit an alternator in the old AirCon condensor space, I can't fit a genset there. | ||
| David Hartley (Drdave)
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Like an LED, Narrow field of view. Guys, This one isn't worth wasting any more time on as he won't listen to reason anyway. He's probably just jerking us around anyway. Anyone who would talk like they were going to spend 10 of thousands of $$$ on solar and some funky electrical setup that is bound to give greater problems than it cures. Is not living in the same reality as us. | ||
| Dale Waller (Happycampersrus)
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David What kinda price tag is on a 600a alternator?? | ||
| CoryDane Rating: N/A |
ok, I've visited the site you list.... your power usage interestts me... >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Here is my first (very rough) guess at power usage: power h/day Wh/day ----- ----- ------ Computer 100W? 24h 2400Wh 19" LCD 50W? 8h? 400Wh Powerbook 25W 6h 150Wh Touchpads 20W? 10h 200Wh Lights 200W? 15h 3000Wh Fridge 522Wh? Stereo? 200W? 2h? 400Wh A/C 1500W 6h?? 9000Wh Water pump 40W 1h 40Wh Furnace Fans 90W 2h? 180Wh ----- ----- 2kW+ 17kWh/day <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< you are using a lot of power, Question, why is the computer on 24hrs? Is the computer/laptop/touchpads all in the same system. Furnace fans are incedible waste of power. I'd suggest that your guesstimate is really low. Look into the furnaces that use no power at all. A nice Solar assited system will be helpful, perhaps you need to think about adding it at the same time. Lighting for 15hr might be a stretch, well depending on how many windows/skylights you have. (((( I want to have the genset start and stop automatically )))) Might want to rethink this.... You won't be real popular at the campsite if the genset kicks in in the middle of the night, and some parks have restricted times for genset runs. (After thought) hooking to campground, which allows charger to keep battery up might keep genset from starting. yea, ok) Are you incorporating the bus generator to charge your coach battery??? I didnot see that in your page. Going completely separate maynot be the answer you look for here. Nice page, you are thinking about the systems. Are you planning a lot of booning????? Ok I would consider the solar panels now. even 6A @24vdc is better than nothing. I would try utilizing the engine genset, I thought they were in the 70amp @ 24vdc, to charge the coach battery, which goes to inverter which feeds the coach 120vac. At campground, the inverter should charge the battery and supply the coach at the same time. BOoning, you would be able to utilize the solar capability and run the engine for the engine gen to charge the batts which feed the inverter which run the AC Lesseee, 70A @ 24VDC = 14amps (more or less) of 120v AC (after inversion). 14amps at 120vac = 1680 watts With some conservation and Solar, this may be workable. My thought CDane | ||
| CoryDane Rating: N/A |
(((( Why do I need to switch? The engine gen does the bus batteries, my gen does the coach batteries, if it's connected/clutched/attached/whatever. ))) Because you want the battery to charge while you are traveling, that way you save fuel, especially with the system you are trying to develope. Diesel engines are not the most efficient operating. Thats why gensets are built with much smaller engines. CDane | ||
| David Ljung Madison (Daveola)
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Dale: ((What kinda price tag is on a 600a alternator??)) Good question. My preliminary research shows it to be around $500. If anyone can find me a full 15kW genset for that much, I'll buy it! CoryDane: ((Because you want the battery to charge while you are traveling)) I still don't understand your question. The alternator that came with the bus will continue to charge the batteries that came to the bus. I want a second, larger alternator that I can connect/disconnect that will charge the battery bank. If I want that to happen while I'm driving, then I'll just connect it to do exactly that. | ||
| David Ljung Madison (Daveola)
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CoryDane, thanks for the great post about the bus. I've created a new topic to discuss the bus in general and I'll reply to your post there. Drdave, feel free to join us, I'm taking the big, non-narrow field of view on that topic! http://www.busnut.com/cgi-bin/bbs/show.cgi?11/12662 | ||
| David Ljung Madison (Daveola)
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CoryDane also said (on-topic): ((you would be able to utilize the solar capability and run the engine for the engine gen to charge the batts which feed the inverter which run the AC)) That's pretty much exactly right, except that the engine gen isn't quite big enough. I don't want to run the bus engine full-time while I'm booning, that would be a huge waste of fuel and engine time. Instead I want something that will better utilize the power of the engine and run for a much shorter time. Charge up a massive battery bank, and shut the engine down. | ||
| CoryDane Rating: N/A |
(((( Instead I want something that will better utilize the power of the engine and run for a much shorter time. Charge up a massive battery bank, and shut the engine down. )))_ My only thought here is the Air Conditioning. You can't carry enough battery to run the AC from the inverter fed by battery. Scratch that from the list right away and you have a lot more freedom for all the other items you listed. It is obvious that you can't run the engine all the time for the AC. If so, you'd be better off just connecting an air con compressor to the engine. If Air Con is part of your design, you need to look at Solar Air Con. Some of the environmentalists sites talk about it as well as some of the Super Insulated Home sites. But Air will not be possible from the battery/inverter combination without driving the battery down in short time. I have a feeling you are leaning in this direction and it is a direction that has never proven out to work without a land connection. Good luck CDane | ||
| David Ljung Madison (Daveola)
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CDane, there is a topic to discuss this - please see: http://www.busnut.com/cgi-bin/bbs/show.cgi?11/12706 It might help you understand my situation if you read: http://bus.getdave.com/Infrastructure/Electrical/ | ||
| FAST FRED Rating: N/A |
Dale: ((What kinda price tag is on a 600a alternator??)) Good question. My preliminary research shows it to be around $500. NOT VERY LIKELY . The cheapest would be 2 -24V recycled coach alts with special step up belting. Auto air cond only handle about 10hp so their clutches would be of little use. FAST FRED | ||
| Dale Waller (Happycampersrus)
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You got me Fred. LOL. I hope David did also! Dale | ||
| David Ljung Madison (Daveola)
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I think it's fairly safe to assume that a 14kW alternator is cheaper than a 14kW genset, no? | ||
| Dale Waller (Happycampersrus)
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Not to burst any bubbles, But my google and yahoo searches have come up with a couple places with an Industrial 600a alt new for around $2500 bucks. An Ebay search has several gensets for around that. You MIGHT build a setup like Fred has suggested with a couple coach alts alot cheaper. | ||
| mel Rating: N/A |
Just FWIW, these guys have bell housing mounted alternators for small engines; interesting, but not cheap: www.polarpowerinc.com | ||
| sylverstone (Sylverstone_pd4501864)
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"Can I run a monster alternator off the engine with the outputs disconnected and not put much load on the engine?" yes, but you'll blow up the alternator. it doesn't take any horsepower to speak of to spin it when the batteries are fully charged, so why don't you just mount it, and use it to charge your house batteries (which should be separate from your starting batteries anyway) there's no reason to disconnect it. -dd | ||
| Richard Bowyer (Drivingmisslazy)
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Although I do not know everything there is to know about alternators, I have designed and built literally hundreds and hundreds of power systems. These systems have ranged from 1000 watts to 1,000,000 watts with output frequencies from 25 hertz to 10,000 hertz as well as DC outputs, and in my experience, you can run an alternator indefinitely unloaded without doing any harm to it. The only load on the prime mover is friction loss in the bearings, windage loss in the windings, and excitation loss in the exciter. Richard | ||
| Gary Stadler (Boogiethecat)
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Hee hee, I think I've said this more than once lately... "Listen to Richard... he's one of the guys here who knows what he's talking about"... |
