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Forum Index : Electronics : Converting regular alternator to 48 volts
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| BenandAmber Guru  Joined: 16/02/2019 Location: United StatesPosts: 961 |
I already have an Onan generator I don't use it and haven't used it since I've built my first inverter It is the most awesome generator I've ever owned as far as the way it's built Generators are loud noisy smell bad and take fuel to run My solar system will likely meet my needs going down the road but just want a little extra just in case Was going to build a gas powered battery charger but decided I will be running my 6v92 anyway and might as well take advantage of that 48 volt alternator will be almost no maintenance regulate itself and be there if I need it plenty of space for it no modifications necessary just bolted on run wire to my battery Bank and forget about it No transfer switch needed That just makes good sense all the way around for me be warned i am good parrot but Dumber than a box of rocks |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
I REALLY don't get still why if you are a fridgy you aren't just going with an engine driven AC Compressor or why you don't go for 24V. 5kw is not that much to pull from 25 and you wouldn't be using that too often anyway if you were careful with your loads. If you have your heart set on 48V, I guess you'll just have to pay for the ( in) convenience. As I said, I'd definitely be buying 2, one to run and one as a spare because if your one and only dies on the road, no chance of finding a replacement quickly.... Unlike a 24V :0) I also think you are underestimating the amount of heat you are going to have to dissipate out of the bus if you are driving anywhere that actually gets hot like 30oC+. I see you say the thing is insulated and I would assume you have a good amount of the windows blocked but insulation only slows heat transfer, it does not stop it. That thing will heat soak and you will have to deal them with removing all the unwanted energy. The internal space of a bus has a lot of surface area. If the thing is a Pusher you'll be better off but if it's a front mounted engine there will be a lot of heat generated there as well. A decent car AC has the cooling capacity of a mid size home AC so even 3 window mounts in a bus ( which seems a lot of hackery and potential trouble to me) I think is going to be marginal at best. Zones in a small area like a bus seems a bit optimistic as well. When you are going down a road with the sun beating down, the heat coming up from the road and there will be an amount of heat soak from the engine, I think the heat load might be a lot more than you are calculating... But I'm not a fridgy and you are so..... I have reservations about the output from your solar and would say the idea of using solar for heating is a particularly poor one, especially if you have an element in mind. Much better to put a Rx valve in the AC units if you go electric and get the better efficiency from those. When it's cold and you want heating, your solar will be lucky to generate 1/3rd it's rated output. I'd think real lucky since from what I can tell half of the panels will be mounted flat on the roof. If you are using the solar for other things like appliances, I think you'll be struggling for power. I am coming out my second winter with a LOT of panels on my house and sometimes I don't even get near half the KW rating of what I have. In summer I get 6X or above. In real terms you might get 3Kwh of you have 6 Kw of panels on a bad day which will be colder and on a sunny winters day you might get 6 KW. I don't think that will go far for heating particularly with an element. As for underfloor, 2 things come to mind there... First is you'll need some sort of thermal mass/ working fluid. You could use your drinking water but that would require putting a HE in the tank and probably insulating it. Second is if your floor is going to radiate heat up though it in winter, it's going to do the same in summer when you don't want it to. You are most likely going to want to insulate that as well. Running pipes under the thing is a complication and addition of a lot of failure points in my mind. For a small area like a bus, I'd just be using a Car heater core and fan, even one at each end. Surely the bus will have some sort of heating system of this type anyway would it not? You have 1000Kg of thermal mass in that screamin Jimmy so I would be tapping into that with a Circulation pump so you could pull the heat out of that when the engine was not running. Quick calc shows If that thing is at 80oC and you pull it down to 25oC, you have almost 60 Kwh of heat there. Iron has less thermal storage than water and you will have piping losses etc but even so, If you called it a very conservative 30KWH of heat storage, that's a lot of heat and might be worth Firing the thing up if you need to recharge the batteries and make use of the Co-gen. Just use the solar to run the circ pump and the Cabin fans. There is a catch here though as well. Diesel has roughly 10 Kwh per Litre of energy. That going to take 6 L of fuel to get that big heavy mass up to temp. At least 1/3rd will be lost to mechanical friction and exhaust heat and you'd want to block the radiator or sh*t it off before the thermostat opened. In any case so you'd be looking at a 10L burn minimum for that heat storage but you could go less. Fine when you have been running and it's up to temp and wasting the heat energy but just for heat... ? You could also look at just running a stainless pipe through your water tank ( No, not a copper coil, 2" pipe will be fine) and pick up some additional thermal mass there. Have a by pass on it so you can shut it off in summer but might be nice to have all hot water in winter. would also reduce your gas consumption for showering etc if the water already had a head start and the time rise you needed to impart was less. A far better solution IMHO would be the Diesel heaters specifically for the job. They have good output, are quite efficient and pretty cheap now. Diesel heater A couple of these should keep you plenty cosy in the coldest conditions day and NIGHT and would be about the cheapest, most simple option for stationary heating. They use little power so you could run one at night without fear of how much your battery's were discharging. I'm considering getting one for my house to test. With the heat output and cost of fuel even here, they are still FAR cheaper to run than electricity. If you did a co-gen setup and preheated the intake air from the exhaust or ran the exhaust though a hot water tank, the efficiency would be fantastic. I understand you are trying to do this on a budget but I think you have to be mindful of the stresses and loads put on things when travelling and the difficulty of cost and repair not to mention how you will be if something fails. Seems to me that the idea of electric cooling over using engine driven compressor is going to be a lot more exy and in fact add more complication and trouble. There are areas where you will have to spend money to accomplish what you want and that is all there is to it. I am tight as a fishes Fundamental orifice as well but sometimes you just got to spend the cash in the first place to avoid spending a heck of a lot more later on. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
I like much of your thinking. I agree. And as the bus already has everything and only needs the Compressor re installed by the sound of it... There are 3 factors I see here: First is cost. I'll bet those 500W panels if available, which I'm not aware of here, would make your eyes water and be a terrible expense on the watt per Dollar scale. Secondly, there haven't been any significan't improvements in efficiency for some years. Maybe 2-3%. As such, the roof area to get say 3 KW of 190w panels up and to get 3 KW of 300W panels up is very similar. The larger the output of panels the larger the panel itself. In my experience it's actualy easier to fit smaller panels because you can get them in areas the larger ones won't fit. Ran into this the other day. Wanted to swap a bunch of 190s for 250s on the back verandah roof which is pitched. All my arrays are 8 panels. No problem putting them all vertically on the 7M roof with 800mm wide 190's, come up a full meter short which is the width of a 250 panel. I can get them up there but I'll have to turn them horizontally which is a LOAD more stuffing round than sliding them up with my feet flat on the ground and securing them. They are a bit under 20Kg but that gets significant trying to manhandle them on a 34o Pitched tin roof. Fitting slammer panels on a bus roof is likley going to be a lot easier than bigger ones and may be the difference between being able and not being able to fit in certain places. Other thing is smaller panels are far more readily available on the used market. All my panels I bought second hand and laugh at the $1/watt number. I often buy systems for .15C/ watt. As the OP already has his panels and will be able to fit essentially the same amount on the bus roof no matter the output, I'd say stick with what he has. 330's are pretty late model and nothing to be sneezed at. In reality the output between 330's and 375's would be diddly squat especially when these things will be flat mounted and subject to a lot of shading and other less than ideal setup. I too have looked at batteries extensively and I would also go for LA if I go down that road... which I prefer to avoid. The best value I have found is forklift packs. with an auto watering system there would not be a lot of maintence and what there would be could simply be written off a s a labour of love and interest. $3K will buy about 3-4X times the amount of storage of one of those ripicolous power wall things. I occasionaly look at forums where people that have them discuss the never ending problems they have... all of which have to be rectified or are caused by big brother tesla who has ultimate and complete control. I have a 6/1 and a bunch of other diesels. Noarly got a 10/2 last year but the seller frigged me around. I am hooking up a Kubota single 12HP to a 12KW Induction motor at the present time. The 6/1 has 2x 90A 12V alts on it atm but I have been looking for a LN 24V I want to put an external staged controller on. There are still plenty of Roids and Listers around in the states. I see them on fleabay for sale all the time. There are a couple of guys on the lister engine forum in the states that sell them. The China clones are also very good and a lot of the guys have them as well. I have a couple and they are fantastic engines and in many ways I prefer them to my roid. I also have a couple of air cooled Ruggerini's, one being a 30 HP and also have a 5 Cyl, 3.0 Mercedes engine I can't bear to part with. Could make some series power with that old girl. Engines are easy to get here, finding gen heads is a battle and a half. Can't even buy them new at anything like a justifiable price when you can find one and they are always like 15KVa and larger. There are a number of inverter/ chargers coming out of China now that will do 5Kw from 24V. The only surprises I'm reading about from people that have them is how well featured and reliable they are. One of these would probably be ideal for the Bus project as the things are certainly cheap enough and are basically an all in one solution which would save time and money in other things needed for typical setups. I personally think 5KW is enough for most things. Only thing I have that would need more than that is the Ducted AC and if I went off grid I'd simply put in some inverter splits with their own inverter probably. I have 3 phase power here and the circuits and phases are broken up so you'd have to try hard to put more than 5KW on any one of them. I offset the draw of the AC now. Have a solar inverter with a Couple of DPDT relays between it and the AC. When the AC is off the inverter sends the power back to the grid. When it's on it trips the relay and the GTI connects direct to the AC terminals and greatly reduces the pull from the grid. There is a reason for doing it that way but would work the same with an offgrid setup to take the load off a regular inverter and take advantage of the cheap used GTI's going round. Having multiple inverters on multiple circuits is good insurance to me as well. If you need more than kw on a single circuit, just fire the Genny. I'll be able to run my ducted air from the IMAG and that's far and away my biggest load. When set to the lowest temp on a hot day it runs non stop so wont cause too may issues I don't think. I can always splice in so DPDT relays on the AC compressor so when it trips out a Dummy load kicks in and vice versa which should keep the Imag in it's happy place. Kinda depends. You don't always have to run from the batteries. I set up a play system where the solar tied into the batteries at the inverter. In this way the draw from the batteries was minimal if not still back feeding. The other thing is forklift packs can run BIG amps in normal use and when you are talking about 1200Ah@ 24V, you can pull them down pretty hard and if you have a few KW coming in from solar or a genny at the time..... I think really it's more about load management and wiring. Cable is what I look at first and foremost at the upper end and is another reason I like the idea of multiple inverters. 6/1 will do 3 Kw, you go up from there with 8's, 10's 12's etc. I'd really like a little inline 3/4 Cyl Kubota or yanmar water cooled. Quiet, compact, reliable and plenty of power. that said the China Horozontal Cylinders like the changfas can be Under driven to make them quiet and even more long lasting. the thing about having to run diesels hard is a load of crap. You can under drive them as many industrial applications do and IMHO are in most ways better than the Listers. 15 or 22Hp Changfa would give you 5Kw standing on it's head and are as cheap and easy(er) to rebuild than the CS types. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Very interesting I do enjoy and appreciate your thoughts And I agree with you 100% I will not be able to heat the bus with solar There is a duct going right down the center of the bus with the hoses for the heater core at the front of the bus I believe you are right about me needing to tap into that and use it anytime the engine is already running for another reason It is a diesel pusher and the motor is not loud at all on the inside my Onan Generator is 10 times louder than the bus just sitting there running We you live in about 1200 square feet and we use 1 14000 BTU air conditioner and one 5000 BTU air conditioner But of course this is not a bus it is a sh*tbox rental unit you're right I may be under estimating the cooling that I need I framed out the inside of the bus with studs I made them myself they are one and a half inches deep by three quarters wide this allowed me to set them in from the metal framing of the bus so I could create a thermal barrier between the big aluminum Heat sink and the inside of the bus like you said earlier me and my wife were talking about pulling a enclosed trailer This would allow for more solar panels without having to have the awning I have some awesome extruded aluminum for the awning already I'm painting the roof of the bus white we've already have the rubberized roof paint and the solar panels will be shading the bus also if I put the awning all the way down one side of it that will create more shade and an outside living space I use a 5000 BTU window air conditioner at the bus currently I recently installed the big inverter and may be using one of the roof units until I take them off We really do not want to have a motor running all the time or even part of the time if we can help it We have planned on getting a on demand propane water heater was going to run it through a electric hot water heater and use extra solar as a dump load in it The wife has been looking for scratch and dent or second hand stainless steel or black cooktop and oven I repair appliances and have always been able to get them dirt cheap We would really like to have a couple mini split heat pumps but any of them that I would want are so expensive Has anyone on here tried the three and four hundred dollar ones from China?? I have been thinking about using a few of the rooftop heat pumps in the bottom but I haven't made up my mind about it yet still open to ideas but I can't have a motor running we will compromise and be hot before we hear a motor running all the time By the way generators are awesome and there's some really good ones out there like you guys are talking about That induction motor generator you're making I would like to hear more about it would be a lot cheaper just to run a generator that's not what I'm wanting to do I want to run off solar and maybe propane that diesel heater sounded pretty interesting also I also like that grid-tie back feeding that a lot of the guys on here are doing I plan on having three inverters only using one but having three backup for my backup The one I recently installed in the bus has one of the 10000 watt Chinese red boards in it the Transformer is only 5000 watt continuous though 52 lb It has 24 Hy 4008 mosfets in it they now sell the same board with 28 mosfets I could be wrong and there's very wise people in here to correct me but I think the main downfall of these type boards are the Caps not being big enough I don't have a big enough battery Bank to even make the fans come on Edited 2019-08-09 13:14 by BenandAmber be warned i am good parrot but Dumber than a box of rocks |
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mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
Davo99, you sound like the man to talk to about Diesel engines  I know very little. (except don't let water get into the Diesel and never let them run out of diesel - had a bad experience priming an old MF40 backhoe, ended getting an external electric fuel pump to prime it) I have acquired a Ruston engine that came with a Southern Cross water pump (it was operational for the previous owner but not so sure now) , a little subaru robin that drives a 24v alternator that charges my LiFePO4 batteries when I'm desperate, a slanzi that is missing its odd sort of generator. Cheers Andrew |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Good Aussie iron there. Happy to talk about diesels, Probably best to start a new thread if there is anything specific you'd like to discuss. I put water in them religiously. Water injection is one of my pet proclivities and have been pumping it into diesels for years with great results. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Is that Ruston air cooled or water cooled ? We had Ruston four cylinder water cooled 45Kva in Antarctica, 6YE series I think they were.I have also seen air cooled Rustons which seem to be more common. Cheers, Tony. |
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| mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
Its an air cooled 1YWA single cylinder Ruston. It doesn't have an electric start, but a crank handle. I'll have to either convert it to electric start or sell it to an enthusiast and get an electric start engine. Not this year, probably not next year either  Cheers Andrew |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Electric start is not that difficult. Just bolt an automotive flex plate and ring gear to the flywheel. Then figure out how to mesh a standard automotive starter motor to it. Cheers, Tony. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
 Can anyone on here guess what this is It's been in my wallet through many wash Cycles and many accidental jumping in the pool The information is so distorted I think it's going to take another person having one to figure it out be warned i am good parrot but Dumber than a box of rocks |
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