| Author | Message | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 97 Registered: 2-2007 Posted From: 75.51.66.117 Rating: |
OK, WE HAVE BEEN HERE BEFORE BUT BEFORE ANY OF YOU CHASTIZE ME THIS IS WHAT I HAVE !! YES GIRLFRIEND GAVE ME A 4048 XANTREX INVERTER/CHARGER,(6)125WATT KYOCERA SOLAR PANELS,SOLAR PANEL JUNCTION BOX,75 WATT SOLAR PANEL BREAKER IN BOX,3 STAGE CHARGE/LOAD CONTROLER 30-60 AMP AND 4 TROJAN 12 VOLT L16 (USED) AND SWOLLEN BATTS WHICH I WILL BE CHANGING TO ACCOMADATE SYSTEM. IS THERE SUCH A THING AS A 48 VOLT TO 120 CONVERTER ??? ALSO MANY HAVE STATED SCRAPPING THE 4048 AND GETTING A DIFFERENT INVERTER BUT IS IT NOT A BETTER SYSTEM USING THE 48 VOLTS ??? PLEASE REMEMBER THAT I AM ON A STRICK BUDGET BECAUSE OF DISSABILITIES AND BEING ON SSDI. ANY AND (ALL) HELP WOULD BE GREATLY APPRECIATED. RANDALL. ONEmule.com | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 40 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
I would talk to Xantrex. They may be able to convert/exchange it to 24 volt without to much expense. Can't hurt to ask. Xantrex customer service 408.987.6030 Same goes for the solar controller. | ||
| David Hartley (Drdave)
Registered Member Username: Drdave Post Number: 780 Registered: 5-2005 Posted From: 97.101.2.69 Rating: N/A |
Heck, I would just go with the existing voltage @48, It looks like it's all ready except for installation. You could always use an older inverter on the 24 volt bus alternator system to run a 48 volt golf cart charger to charge the 48 volt system. That only would run when the engine is running. The general rule is; 12 amps @ 12 volts is 6 amps @24 volts and 3 amps @ 48 volts, So that said the higher the battery system voltage the better the conversion rate and the lower the conversion losses. If I had a 48 volt system like that I would trip all over myself trying to get it installed. Then use 8 of the L16's to feed the whole thing. Sounds like it would be a very efficient system. Much better than trying to start at 12 or 24 volts and get up to 120 volts. The solars are already setup for the 48 volts as is everything else, I would just use it like designed. You could always tap off a little 12 or 24 volts for other things very simply without having to redesign the whole thing. Anybody that tells you different, Doesn't understand OFF-GRID solar systems so I wouldn't trust all the misdirection they will offer. The higher the base battery voltage the higher the conversion factor. Stick with the 4048 , You won't ever have to worry about overloading the wiring. | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 123 Registered: 12-2000 Posted From: 151.213.166.189 Rating: N/A |
All the telephone companies run on 48 volts and there probably are surplus chargers and other equipment available. I agree, the higher the battery voltage, the better the system, smaller wire, higher efficiency etc. Len | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1115 Registered: 10-2003 Posted From: 216.9.250.6 Rating: N/A |
The Dr. Be right on. In fact I went to a day-long solar class a few weeks ago and the instructor was constantly referring to 48 & 24 volt systems as "low voltage." The big boys run a lot higher than 48. Man, I want your girlfriend!!! (Message edited by chucks on June 20, 2007) | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 100 Registered: 2-2007 Posted From: 75.51.66.117 Rating: N/A |
Thanks All !!! that being said now to install it, Been wondering if i should ask my girlfriend if she could do it  get your minds out of the gutter i mean install the system . The Detroit mechanics in las Vegas want $500 to run the racks on my 6v92 is that about the going price ?? | ||
| David Hartley (Drdave)
Registered Member Username: Drdave Post Number: 782 Registered: 5-2005 Posted From: 97.101.2.69 Rating: N/A |
If they do it right, Let them get dirty and set them up to specs. Around he anybody that does 2-strokes gets $65 a hour. In a bus in the confined spaces it takes time to get into stuff which includes strained necks. Was there a specific reason to have the racks run? Or was it just for your own satisfaction? Dave.... | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 101 Registered: 2-2007 Posted From: 75.51.66.117 Rating: N/A |
After purchasing bus would like to know some specifics and make sure its up to par. when i drove it to Boulder Nv from Orange County Ca it was smoking some and not even sure what injectors are in it so i thought it would be a good idea to have it done along with ALL fluid changes. Must say tho it ran really hard on the flats but was a Dog on hills, was told that is to be expected, if i let her go she would run 80 plus on straights, and she did, just wanted to see what she had in her but she liked 73-76 mph.Randall RJmule.com | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 199 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Hey Doc, A couple of questions: Why is an off-grid person not qualified, and their knowledge to be disregarded? It seems to me that an off-grid person is charging his deep-cycle batteries with solar panels thru a controller, and using a generator for backup on rainy days? This kind of sounds like a bus to me, except that an off-grid house has more room for panels! Then you suggest he could "BUY an old inverter and a 48 Volt golf cart charger to charge his batteries while driving." Budget limitation WAS mentioned, not to mention the space that these two items will take up, the fuel it will use to haul their weight, and the wiring and controls to accomplish it? Then "You could always tap off of 12 Volts to run some little loads." Well, a whole lot of the little 12 V stuff is frame grounded, with one wire off of it for the hot. So, he's going to insulate the frames of these from the chassis, and run a seperate "ground" from each of these to his 12V pair? Most of us know what happens when you discharge one pair of a group of batteries in series, and then try and charge them all, so to avoid this, he would have to set up four sets of 12 Volt isolated grounds to make it work without abusing batteries. (Four seperate sets of 12V fuses?) I AM well aware that he would have to do this ONCE, with a 24V system, and a diode separator for charging, BUT CHEAP, SIMPLE AND RELIABLE. Now, this "conversion factor" you are talking about, "2 Amps at 48V is 4 Amps at 24V, and 8 Amps at 12V." I can only ASSUME that you mean those terms equal the same number of WATTS? I don't understand your statement of "higher conversion factor" at all, and I would like you to publish a recognized source. I will GUESS that you are trying to say that higher voltage takes less current to provide the same power, (watts) so a higher battery voltage system would take smaller cabling? I would like you to read the post on "Batteries," with a last post date of June 6, as it really applies to this thread, especially the parts about lack of capacity and battery life. My suggestion? Sell the 48V inverter to an "off-grid" person, buy an equalizer and a 12V inverter, and he will arrive at his destination with fully charged batteries, without abusing them, and he won't have a complicated wiring mess that won't work well, and nobody can figure out. He'll have all the 12V DC he needs for his non-inveter loads, and it will WORK! I won't ask why the panels came off the roof, and the batts are bulged, nor will I suggest that other posts be ignored. George (Message edited by George Mc6 on June 22, 2007) | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1117 Registered: 10-2003 Posted From: 68.240.247.115 Rating: N/A |
That's what the solar is for. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 200 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
All 750 watts of it? At 48 Volts, that's 15 Amps. With 10 hours of 100% output, that's 150 amp hours per day, or 2 1/2 days to get a full charge on a nominally 300 amp-hour battery. (If there was NO load!) I don't want to spend RJ's money either, but I do think the idea of this is to suggest something that will WORK? I suggest that the post on "Batteries" from a couple of weeks ago be read in it's entirety, again. They have a 24 Volt coach which apparently doesn't charge its house batteries from the engine alternator, AND a "lack of capacity" problem. Since these inverters were bought for off-grid, were they bought with optional battery charging? If they weren't, this system won't work at all. If they were, RJ goes down the exact same road as the "Batteries" posters, (uphill, windy, bumpy, and dusty.) "Is there such a thing as a 48 to 120 Volt converter?" Isn't that a 4048 Xantrex? I didn't want to whizz on his campfire, but it was a windy evening...? George | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 104 Registered: 2-2007 Posted From: 24.152.156.145 Rating: N/A |
the Inverter/charger is a 4048 with Gen and shore power capabilities along with excepting power from solar.yes the inverter will convert to 120 hence INVERTER !!! so the Xantrex rep states. Guys i just thought this was the way to go since i have every thing except the ATS ??? | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 41 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
RJ, the bottom line is, if the solar does not keep up, your only options to charge the 48 volt batteries will be power pole or run the generator. You will NOT be charging your house batteries when driving down the road other than solar. Now if like many busnuts, you run the genset for AC most of time when you are on the road, it may not be that big of thing. Personally I like to arrive at camp with fully charged everything. If you plan boondocking a bunch, like everyone else, you will learn to exist on solar and genset. Be aware that at 48 volts your coach will be even more unique and you may have to look to solar type stores for repair and maintenance. Be careful, the higher the volts the more it bites! The other thing to keep in mind is that if at some point down the road you want to go with a more 'standard' setup it would not be that big of deal. You would need to rewire the batteries to lower voltage, build new heavier cables and put the new inverter in place of the 4048. Don't know solar so not sure if your controller might work at lower battery volts. Good luck with what ever you choose. | ||
| James Robinson (Jjrbus)
Registered Member Username: Jjrbus Post Number: 79 Registered: 12-2000 Posted From: 76.1.180.218 Rating: N/A |
RJ The only downside I see is 1, you will not be able to charge the batterys`from bus alternator, for running roof air or 120V applications when traveling. You can still use 120V, but must use gen, or solar to recharge batterys. Also most (most not all) spend far more time living in thier coach than driving it, so it is not that big a deal. 2. You cannot interconnect bus and house batterys for redundency. Again not that big a deal, but nice to have. 3. If you have any 12 or 24 volt applications it may be difficult or expensive to draw it from house bank. I have no experience in this area, but it is something I would think about or look into befor proceeding. If you center tap 48V you have 24V, you can get 24V water pumps, macerators and lighting. Anything in low voltage RV stuff will be 12 volts. Anything you want in low voltage will probobly be from the marine stores and can be very pricy. However everything is available in 120V, so that may be the way to go. HTH | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 201 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Well, one last try, my post of June 22 was pretty long, so I guess nobody read it. What did Wilbur say? (Answer later) "!IF! the solar doesn't keep up?" These panels put out 750 Watts total brand new in full sunlight. 750 Watts divided by 48 Volts = 15 Amps, Thats FIFTEEN! If the house batteries are rated 300 Amp-hours, thats TWENTY, 20 hours of bright sunlight for a theoretical full charge, if there is NO use. "Center tap 24 Volts"? Well, I think I said something about isolating 12 Volt loads, not discharging one set of 12 Volt batteries more than the rest, insulating the grounds on three of the four 12 Volt loads, and four sets of twelve volt fuses? Yep, you can't "center tap" 48 V and get 12, you could tap each pair of 6s, and get 4 sets of 12, IF you insulated the grounds on all the appliances, on three of the four sets. (Maybe grounding the 48 V wouldn't be a good idea either, think what would happen when somebody touched the wrong wires together?) The smoke would probably ALL be let out... I appreciate Don's comment about "even more unique," (Do we get his drift?) as in how many RV shops can jump right in and work on it? Once again, look at the posts on "batteries," theirs is a coach with no OTR charging, lack of capacity complaints, and short battery life issues due to heavy discharging. RJ's bus will behave the same. We also don't have a reply to the question of why the panels were removed, not to mention the bulged batteries, right? I hate to beat up RJ in his own thread, we've beat up Dutch on his, and he's taken it well, so here goes. The question, "is there a 48/120 converter?" sets the level of electrical qualification. (There, I haven't said anything really bad, have I?) I also want to be clear, I don't like to go around knocking other advice, I just want to explain the ramifications of this, and the electrical math involved, to try and explain why this won't work well, and why a bunch of money shouldn't be spent on trying to get whiskey out of a wine bottle. We won't chastize you RJ, we'll just castigate you! Won't fly Orville! (Message edited by George Mc6 on June 24, 2007) | ||
| David Hartley (Drdave)
Registered Member Username: Drdave Post Number: 784 Registered: 5-2005 Posted From: 97.101.2.69 Rating: N/A |
Uh.. Well The only point that I was trying to make was that since he already had a whole system designed to run at 48 volts, And since the budget is limited it would just make sense to hook it up the way it is currently designed. There was no negative issue meant about on grid and off grid. Just a thing that someone might take issue because his 48 volt system would not be the "NORM" of most bus conversions. People take offense if someone wants to do things differently for some stupid reason these days. And.. as for tapping small 12 or 24 volt loads. Nothing wrong with that. Chassis ground and solar/battery ground should be tied together anyway and not isolated. Sure if you use too much tapped power you could cause an imbalance but not as scary bad as people make it. George, Weight issues are non-issues in a bus conversion. You should know that since your conversion is one of the heaviest on the road. Adding a couple hundred pounds is not an issue and whoever thinks it is should take a break and get real. Because if that was a problem then we all would have to run with empty water, fuel and holding tanks so we don't upset the critically fine balance of our coaches.. ( Haaahaaheee ) The thing about the charger was only a simple quick idea. The better way would be a 24 to 48 volt d.c. to d.c. converter that could be tapped into the coach wiring with a relay so the house system would get charged when the engine is running. But then with no working budget that isn't an issue. As for questions why the panels were removed, Who cares as long as they work. So batteries swell... maybe from age? Doesn't matter either. They would get replaced anyway. George, I am not going to waste my time going and getting source documents to support everything that I say. That's just dumb to expect a person to back absolutely everything up by documentation. If you are one of those people that expect that kind of thing.. Good Luck on that buddy... No system is perfect and there will always be differences because there are differing points of view. I was trying to help. I do know things about grid and off grid systems and mobile systems with voltages up to 364 volts and inverter systems along with cell site and industrial UPS systems. All different and yet all the basic same. Only the budget and voltages vary. "Flame OFF".... E-Gads... | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 202 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Doc, The reason I asked for written support was not "because "I am one of those people," it was because you can't produce it, because it doesn't exist. I did ask politely for it, and was hoping for a tangible explanation of why a 48 Volt system is so much better than a 12 or 24. Obviously, I didn't get it. I care why the panels were removed, and I care about their age! #1. People usually don't take out good working stuff. #2. Please read the prior posts carefully, and pay close attention to the comments on "maximum charge capability." #3. Budget constraints were mentioned at the start, your suggestion to charge his 48V system OTR has him buying a 24V inverter AND buying a 48 volt golf cart charger, just so he can use his 48V inverter? #4. "The better way would be a 24 to 48 volt d.c. to d.c. converter...But then with no working budget that isn't an issue. #5. "Thats what the solar is for." (By someone else.) #6. "However, everything is available in 120 V... (By someone else.) Answers to what I have said: #1. Stuff gets taken out because it DOESN'T work as intended. I asked about the age of the system because solar panels wear out. Not as quickly as properly used batteries, definitely not as quick as batteries installed in an improperly designed system, but the deterioration rate of solar panels IS published, and averages a couple of percent per year. #2. I posted the Voltage, Amperage, Wattage, charge rate, and approximate amp-hour ratings of an average deep cycle battery in an attempt to explain why this system wouldn't work well in a bus. Please go back and read the original post again, and stop and "think about it a while." Specifically "SIX KYOCERA 125 WATT PANELS." Multiplying 125 by six gives 750 right? (That's 750 total wattage output, new, in bright sunlight.) Dividing 750 (Watts) by 48 (Volts) gives 15.05 Amps, again, NEW IN BRIGHT SUNLIGHT! Now that WE understand how many amps this system will put out, theoretical perfect, we need to divide the output into the battery amp-hour rating to determine how many hours it will take to fully charge the batteries. 15 into 300 sounds like about 20 HOURS to me. In reality, that won't happen, because as John put it very well, "deep-cycle batteries aren't fuel tanks." A properly working charge controller will taper off, or stage off, charge rate as the batteries approach full charge, so the actual time to fully charge a 300 amp-hour battery, at a 15 amp charge rate will EXCEED 20 hours. Those hours are not sunrise to sunset either, and require proper panel orientation and tilt. I put solar water heating on my last house, because it was all electric, and the proper pitch of the panels for that location was 5 1/2 in 12. Now, are we going to orient the bus exactly East or West, depending on which side of the bus the tilt is, and leave it for 10 hours? I won't even mention that about a 5 in 12 pitch (just about right for Laguna,) will make the bus 15 or 16 feet high. Flat panels will only produce maximum output for about 6 hours a day in the middle of summer. A 10 SEER, 13,500BTU rooftop air draws 1350 Watts. With this systems ability to produce 750 Watts (theoretical perfect, AND a 100% efficient inverter, which all of us know doesn't exist,) this system would have an HOURLY DEFICIT OF 600 WATTS! Think about that for a while, that deficit is 4/5, or 80% of the solar output. Now it is time to refer to #1 above: People don't take off stuff that works. I read the first post, I paid attention to it, and acknowledge that there were two systems. As you can see from the above calculations, BOTH systems will just run one rooftop air. #3. Budget constraints and buying a 24 Volt inverter to hook up to the bus alternator to provide 120 VAC for a 48 Volt golf cart charger just so he can use his 48 V inverter????????? There just aren't polite comments to be made about that one, but YOU used the word "dumb." #4. A "24 TO 48 volt d.c. converter to charge his house batteries OTR." I hate to be the first one to tell you this Doc, but you can't transform DC, period. Higher to lower voltage converters, (battery equalizers) use transistors, silicon controlled rectifiers, gate-turnoff thyristors, and other stuff to vary the resistance according to the load, and drop the voltage accordingly. Remember #3? Not to mention that a low to high voltage converter doesn't exist, but your post would have had him asking where to find one. KEEP YOUR HANDS OFF THE KEYS, @#&$%^, there's been too much posting here without thought already, how many of us know what a 24 to 48 volt d.c. to d.c. converter really is already? ROTFLMAO? #5. Just read the replies to #1, and #2. #6. "Everything is available in 120V. Well that would work, and would take a continuously idling inverter. Nobody has explained to RJ yet that maximum inverter efficiency is about 90%. Is my drift starting to appear yet? We do need to GET Don's and James's drift, because they are both explaining the problems in a system like this. I really hope the meaning of "unique" is well understood! "One line posts usually don't reflect any thought either." Bottom line? As I said before, I only want to help, and my track record speaks for itself, when I disagree with someone, I post the published facts, whether it be the Natinal Electric Code, or whatever. No derogatory adjectives, and just as I have done here, I will explain. So, in the interest of saving money, RJ is going to put in a system which couldn't power half a house, as described above, and expect it to run all of the house accessories in his bus. We all agree that he has NO OTR charging capability, (from his chassis) and I hope I have explained clearly, very little solar battery charging capability. We haven't heard it stated clearly yet, that these inverters were bought with AC to DC battery charging capability, remembering that they were bought for a solar application. Once again, the question: Is there a 40 to 120 converter? Answer: The guy from Xantrex says its an inverter. This means to me, a UNIQUE bus with a non-highly electrically qualified owner. (Sorry RJ) That alone to me means Trouble, with a capital T. 12 V house loads would require isolating the grounds on all the fixtures except for the circuit run off the 12V battery with the grounded terminal, the other three would HAVE to be insulated, and a seperate negative run through fuses to each battery negative terminal, along with its related positive. I suggest this, because if all of the 12V loads are taken off one battery, #1, it just won't have much capacity, if charged, #2, the 48V charging system will overcharge the other batteries in series, trying to charge the one low battery. And, actually the charging system only sees the total voltage, and so this would just be another part of the system that wouldn't work well. With inverter efficiency being about 90% average, ignoring idling losses, this leaves RJ with about a 690 Watt system, for about eight hours a days in the summer, the way I figure it. That is why I suggested that RJ sell his inverter to an off-grid person, and get a 24 volt system. Yes Doc, I would rather have a 24 than 12. OTR battery charging, with a cheap solenoid, use of ALL of your 120 V stuff while OTR, arrival at destination fully charged, a system most everybody understands, 12 VDC easily available with an equalizer, the list goes on. He does want to do this so he can use and enjoy it. I want to recommend something that will work. Doc, I put considerably more thought into this than you did, and that's all I will say about it. What is a 24VDC to 48VDC converter? A 24 Volt inverter, an a 48 Volt golf cart charger! I need a beer, and its too early! | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1118 Registered: 10-2003 Posted From: 70.3.118.218 Rating: N/A |
I *really* shouldn't get into this. I *really* shouldn't. I don't have solar power yet, not because I don't want it but because it's further down in the project list. I don't want to be a numbskull about this and behave like many of the typical RVer crowd, but I *do* know that there are quite a few knowledgable RVers who are tickled with 24 hours of solar operation with less wattage than this and who typically start their generator only on overcast days -and- don't get any OTR charging either. They travel in climates where AC is not necessary, and unwanted. But it is certainly not worth documenting and going to find all those links just to prove it. I don't think *anyone* would expect to power their AC from the batts and expect solar to do the trick, and unless I missed something, the OP didn't expect that either. It is my understanding that 750w is quite a desirable level of performance for the RVer who is looking to go this route. (Message edited by chucks on June 24, 2007) | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 402 Registered: 7-2006 Posted From: 68.205.165.5 Rating: N/A |
This DC/DC converter is useful for voltage conversion to operate 48 volt electronics off 12 volt vehicles  | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 105 Registered: 2-2007 Posted From: 24.152.156.145 Rating: N/A |
FYI. these panels are (only) 2 years old, removed because of sale of home and appraisel did not warrant leaving them with sale of home. It is a big problem in palm springs or any where the temps are in the high 100 for several months per year. the heat KILLS batteries !!!! sorry for all the ?????? Randall | ||
| David Hartley (Drdave)
Registered Member Username: Drdave Post Number: 786 Registered: 5-2005 Posted From: 97.101.2.69 Rating: N/A |
Hi Again, George, Sorry to burst your bubble "again" But dc to dc voltage converters up and down have been around since the invention of the transistor. Of the many many ones available here is a link to at least one of them. http://store.altenergystore.com/DC-Voltage-Converters/Solar-Converters-Eq-2448-10A-2448V-U pDown-Conv-Prop/p1292/ If you had a background or have been following electronics designs from the trenches like I have you would not have said that "They don't exist". I know they do, I worked for Stromberg Carlson as an engineering tech. One of my jobs was repairing dc to dc voltage converters used in telco systems. and that was in 1977. The next point is that almost everything electronic these days that doesn't have transformers use some variation of dc to dc converters. Any Inverter is that type of system. DC can be made from any inverter using diodes. aka if you wanted 120 volts dc you would take an off the shelf inverter and add a rectifier and filter to the output...gee..this IS rocket science. Anyway... As for documenting what I say, Just about every alternate energy website/store and installer can verify and provide reading documents on everything. It's not that hard or confusing. But if you want to wave a flag saying that none of it is possible, Go ahead.. I don't care... I just think that some of your statements came from a rather jilted view of things. If you don't understand something then you say you want everyone else to prove to you it does exist. Always Learning... Dave Oh and, Nobody generally runs their A/C off their "solar" charged inverter system as a rule. If they do it's for very short periods mainly due to the massive amount of power required. And I didn't go there because I accepted that fact silently. My Solar in my bus charges batteries to keep my 3,000 watt inverter ready in idle mode and runs my 12-volt lights and 12-volt fans and my 120 volt refrigerator otherwise. I don't have to keep the bus plugged in and on charge. The solar is automatic. ( I don't heat water or run a/c with it either!) (Message edited by Drdave on June 25, 2007) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 207 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
Doc, I appreciate your last post, its much more positive than the earlier one. Trenches? I do have an Associate Degree in electronics, and I am a licensed electrical contractor. I do own a bus, before that it was a motor home, and before that, a cab-over camper. Lets just look at this whole situation a minute, and you will see where I am coming from. I have posted nothing but Ohm's law, plus taking an average amp-hour rating of a battery, the output of the solar panels, inverter efficiency, and tried to put it all in a simplified perspective, that non-electrical types can understand. As an electrical contractor, I regularly get requests to "put 220 in instead of 110, because its cheaper." Then I have to explain Watts, and a Watt-hour meter, amps vs. volts, line to neutral loads, etc. and the person stays with his 3-wire 120/240V electric service! I am well aware of the cable size requirements of battery banks, and the effect that increasing voltage has on reducing cable size. I would personally have a 24 Volt system over a 12 Volt, anytime, as long as my chassis was 24 Volt. I try hard to make common sense posts, using the least possible amount of equipment, because the least complicated system will have less trouble, simply because it has less parts. Inverter manufacturers definitely publish cable sizing requirements, and they are real strict about 12 V sizing, due to the high current required to produce the necessary wattage at low voltage, not to mention the voltage drop at high current flows. I will assume this is what you were getting at in your first post, if so, just say so! But remember Catch 22, (If you have to ask, that means you don't know) right? I'm NOT referring to you, but to the original post. Of course, RJ could put this 48 Volt system in, and the panels on the roof, but what would happen, with no OTR charging, and no 12 Volt available without some fancy circuitry? What would happen if he were to tap off the last 12 V batt, and run all of the ususal 12 V loads off of it, all by itself? You do have to remember that now there are four 12 V batts in SERIES. That means that the charging current for the one 'house' batt has to pass thru the other three. What voltage is the charging regulator going to see? Please don't get defensive, I'm not jumping on you, I'm explaining my thought process, and I have put a whole lot of thought into this. I feel pretty strongly that the one batt used for 12 V wouldn't charge well, and the other three would obviously be over-charged? How much? Who knows. Please, read the post on "BATTERIES" I think the last post was 6/09. This is essentially the same thing. A 24 V coach with no OTR charging, due either to a failure, or an omission by the previous owner. The present owners are getting 5 hours of a residential refrigerator, a light, and a TV off of a charge. Then they have to gen set, or shore to recharge. They are also unhappy with their battery life. That would drive me wild, knowing I had a 175 Amp, 24 V alt back there running at less than 20% of its rated load, and I could arrive with a full charge, AND use anything I wanted on the way, including a roof air. So, I would use a continuous duty solenoid, wired into the Air Conditioning cut-off relay, because it is there. Others have suggested oil pressure, and fuel pressure control, which will work well also, or a diode seperator. IMNSHO, buying a 24 V inverter, and a 48 V charger, for OTR charging (which has been suggested) just to use the free 48 V inverter doesn't make sense, either economically, electrically, or practically, not to mention the vented bay space this equipment would take up. Now, I get a picture of a 12 to 48 dc converter, THAT PLUGS INTO A CIGARETTE LIGHTER! AFTER suggesting that we keep our hands off the keys, because there hasn't been enough thought put into these replies, AND explaining what a 24 to 48 dc converter was at the end. I'm going to hear from John, after I thought this thing had been put to bed! Where is the 12V cigarette lighter receptacle in RJ's 24/48 bus? I never said it wasn't possible, that is obvious from the posts. I said then, and I will say it again now, as described, with six-125 Watt panels, AND NO OTR CHARGING, RJ WON'T BE HAPPY, BECAUSE IT WON'T WORK WELL, PERIOD. I agree 100% with your last three paragraphs!!! Doc, you still haven't told me why YOU think a 48 V system is so much better, I would like to hear your reasoning. I asked you to document it for a reason, and what I got was, in my opinion, a "defense in the form of an offense." You have posted your opinion of why I did what I did, so I am entitled to mine of yours. I really would like you to show me a dc to dc converter that INCREASES voltage, WITHOUT A TRANSFORMER IN IT! RIGHT IN THE MIDDLE OF MY LAST POST IS "TRANSISTORS, SILICON CONTROLLED RECTIFIERS, GATE TURNOFF THYRISTORS, ETC. I don't think you read it all carefully before you jumped! Now, your paragraph on 120V DC is blatantly wrong, I wouldn't have said it until "bubble," but AC power is measured as ROOT MEAN SQUARE, RMS, which is .707 of peak to peak voltage. This means when you full wave rectify 120VAC, you get 155VDC. This post is too long also, nobody's going to read it and remember half of it. Please remember UNIQUE, and what was meant, no OTR charging, (no OTR charging also means a deep-cycle every time the bus is driven with any load on) and 675 Watt-hours total capacity, @90% inverter efficiency, at 100% panel output, (noon on a clear day) and no battery loss, 12 VDC problems, and if that sounds like something to recommend, DO IT. (Message edited by George Mc6 on June 26, 2007) | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1930 Registered: 1-2001 Posted From: 75.108.76.30 Rating: N/A |
Any DC to DC converter that I have ever seen takes, for example, the 12 volt DC and chops it up to a very high frequency, maybe 50khz., to change it to AC. This is to keep the transformer and other components very small. The AC is then stepped up with a high frequency transformer to the desired AC voltage required that will then be rectified to obtain the desired DC voltage. Richard | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 410 Registered: 7-2006 Posted From: 66.217.105.152 Rating: N/A |
RJ - I'm obviously -not- an engineer. That link I posted will give -you- an idea of the many types of dc/dc converters that are available.... (Oh, and that outfit will build to suit)... I, personally, would prefer to keep things as simple as possible, and run everything with the most commonly used voltage. But.... There's absolutely no reason that you can't do it with 48 volts and use small, inexpensive converters and inverters to get the "other" voltages you need. Those small (plug-in type) converters and inverters can supply what you need, where you need it, at throw-away prices.... Cheers. Oh.... and.... Some engineers will show you how to make possible, what appears impossible... while other "engineers" will recite the theory why it should remain impossible. (no insult intended, to whomever the shoe may fit) Lotsa' luck RJ.... (Message edited by john_mc9 on June 26, 2007) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 209 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
Gosh Darn, I feel neglected! On a serious note, John. The battery post the other day was beyond excellent! Thx! George | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 120 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
What do you mean? Read the whole thing from beginning to end. Joe. | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 411 Registered: 7-2006 Posted From: 68.205.165.5 Rating: N/A |
Joe - Out of curiosity, who were you addressing that comment to? | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 121 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
John It was very late (early) when I typed that post. Should have been in bed at least a couple of hours. That comment was referencing to Georges post of June 24 at 1 29 AM referring to one he made on June 22. wherein he said that probably nobody had read it. It looks that he also burns the midnite oil. My post should have read "George what do you mean" If any misunderstanding has arisen because of this, I offer my sincere apologies. Joe. | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 122 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
On another note for Randall. Solar panels of the capacity that you have are typically of the 12 volt variety (each individual panel) so you have lots of flexibility if you were considering a different route to go, eg 24 or perhaps 12 volt. Is your solar controller fixed at 48 or can it be configured for something else? Joe. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 210 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
Joe, There certainly wasn't any upset on my part. You have made many helpful posts in the past, without any inflammatory comments, and in my opinion, that is the name of the game. As you noticed, this thread got way off the subject, and several of the replies weren't relevant. IMO, starting off with "What do you mean by...?" is exactly the way to ask, because it allows an answer, and/or an explanation, without causing upset! This thread dumped so much on RJ that HE apologized, and he didn't do anything wrong! Anyhow, THANKS! George | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 413 Registered: 7-2006 Posted From: 66.217.107.75 Rating: N/A |
George - "Dr. Dave" summed it up nicely in his first post to RJ (it's post number 3 in this thread). RJ has a free 48v solar system, complete with everything he needs to get things going. All he needed was some help in figuring out how to tie it in with a 12 and/or 24vdc system. Instead, Ol' RJ has received enough technical boogahlooga to make even the most demanding engineer's head swim.... There's more of a problem in mounting the solar panels atop the roof (and managing to keep them protected from branches, etc), than with using a 48vdc solar system with the inherent 12 or 24 vdc conventional system in a bus. No, sometimes "free" isn't the same as "easy".... But when it's all a guy has to work with, it'd be nice for him to hear some thoughts that help to reach his desired end, rather than to just further confuse the issue. We usta' call it "Yankee Ingenuity".... (No offence intended, Ma'Man. Youse really did mean well!) | ||
| RJmule (Rjmule)
Registered Member Username: Rjmule Post Number: 108 Registered: 2-2007 Posted From: 75.51.66.117 Rating: N/A |
A'men and thank you ALL for your advice.... Rj. Randall. I will repost this again at a later time for a fresh imput | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1120 Registered: 10-2003 Posted From: 68.240.30.94 Rating: N/A |
Well, if you're going to let 'em sit around, RJ, I know a GREAT, RESPONSIBLE, RELIABLE and all around Good Fellow who will hold on to 'em fer ya! |
