| Author | Message | ||
| R.C.Bishop (128.123.62.214)
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Anyone have any comments on the extensive use of one type versus the other? i.e., fridge, heaters, water heater, micro, etc. and how they even out over the long haul. I am assuming frequent use and fulltiming for a month or so at a time. Up front costs are heavy on 12VDC, but will they make up in batteries required, size of inverter, recharge time, etc. I've read some seemingly conflicting information and just would like some more input....  Thanx. RCB | ||
| Doug Dickinson (Dougd470) (65.161.188.9)
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Here's my 2 cents worth - based on both research and marine applications from WAY back (we don't want to get into HOW FAR back). I am just now building a bus and here is what I am doing and why - 12volt stuff generally has to use a brush type motor to spin anything (like a blender or a fan) whereas an AC device does not. Brushes in a motor are a maintenance headache - necessary but not my favorite PM item. 12volt devices are expensive up-front for the most part. 120VAC is cheaper and more familiar to the user in most cases. From an efficiency standpoint (never could spell worth a darn), a 12VDC device will require much larger wire from the battery as the wire is rated at AMPS not WATTS. In addition, with the lower voltage, there is voltage drop (resistance) which reduces efficiency overall. In the 120VAC world, the voltage drop for a given length of wire (same amperage and guage wire) is much less. When you factor in the typical invertor with around 10% loss, you are still probably ahead with the 120VAC alternative. Overall power use from the batterys won't be much different if at all. Now for the big finish - either way will work. You will probably spend more money on 12VDC in both the short and long run. You can fix/replace the 120VAC equipment easier than the 12VDC stuff. Some articles are not available at 12VDC. Now, having said that, there are exceptions to the above. If you want a stereo in the coach, a 12VDC automotive type is not a bad idea. They have most of the functions of a 120VAC unit now. Also, maybe a fan or some lights are a good idea on 12VDC to get the coach running, for the convenience of middle-of-the-night-to-the-bathroom or other purposes. Now, what I intend to do is this - All AirConditioning will run off a generator. All other interior stuff will be off the invertor, except certain lights, which will be 24VDC as will the inverter. For the small number of 12VDC devices, I intend to use a convertor back from 120VAC to 12VDC since the power supply output is very regulated and has NO ripple or variation and will keep my 12VDC stereo and a few radio items running nicely. I will take the efficiency hit of about 20% which will pan out to about 200 watts if everything is on full speed off the batteries. | ||
| Doug Dickinson (Dougd470) (65.161.188.9)
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And here is part 2 of the above - For heat, I will use propane. This will also be the supply of choice for my water heater, although I may put a electric heating element in it also to speed up the process. I don't plan to do a lot of boondocking, but I want the option for a couple of days if available. The Refrig will be propane and 120VAC - no 12volt operation - really inefficient at 12 volts, and I won't have 12VDC to speak of. As Fast Fred said before - the Becks (or in my case Yuengling) belongs in a chest with ICE on it . So - what will I have? A cluge of 120VAC, 24VDC, 12VDC and Propane. I was going to use gasoline for my gen set, but I think I will go diesel anyway - even if it isn't the best from a technical standpoint, I don't want another fuel or power system to deal with. It is confusing enough already. Remember - your way is the right way for you. Mine is for me and so forth. Learn, read, talk, listen (mostly listen) and you will find your best way. Don't forget to change your mind once in a while - it keeps people guessing. DD | ||
| dalefleener (66.42.91.157)
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If you are going to be using LP anyway, why not think about it for your gen set? Might be better with light loads. | ||
| DaveD (216.18.113.69)
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12V lights, fresh water pump are fine. They are reasonably cheap and easy to get from any RV supplier. I have a converter charger that provides 12V dc when connected to shore power and maintains the charge on 12V house batteries. The refrigerator is 120V ac or propane - Refrigerators I've had never seemed to work that well on 12V. However the refrigerator need 12V dc for the electronic control circuits in it. One other plus of 12V devices is that they don't present a possible shock hazard like 120 V devices do. | ||
| David & Lorna Schinske (Davidschinske) (206.148.180.144)
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Most people will go with a variety. We prefer Tankless water heater, Range & Coach heat to be LP with a exterior connection for the gas grill. Inverter for micro, kitchen small appliances, dishdrawer,tv/vcr. 12VDC for Sunfrost ref/fzr, lighting, auto-type radio/CD player. This is what we decided would work for us. You need to think about how & what you will want & need. Also allow for future changes. We will eventually add a combomatic washer/dryer and change the girls bedroom into an office (will need connections for computer, printer, internet hook-up, phone). Lines/chases will be installed during construction. There is no ONE right way. You are converting for you not the general consumer. Check out all your options and choose which one suites your (& spouse?) needs. Lorna | ||
| R.C.Bishop (128.123.88.47)
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Lorna..is your tankless electric or LP? How do you like it? RCB | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.164.175.139)
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When we wired up our small solar off grid cabin years ago, it was decided to have everything inside standard 120 vac. Actually saved enough on the fixtures, wiring and the rest of the stuff to almost pay for a used Trace 1500 watt invertor. Prior to that had a small 17 foot 5th wheel which had lots of 12 vdc stuff which always caused problems due to quality control and high maintenance due to the bumpy ride and the cheap nature of the then available 12 vdc goodies. The juice required to run the various stuff will be about the same, only the configeration will be different. 120 vac vs 12 vdc. With the progress and reliability experienced with modern invertors, I am going to have my coach be 100% 120 vac. The chassis will remain the existing 12 vdc. The 'house' will be 100% 120 vac. No propane. This however places great reliance upon the invertor--if it blows, then the entire 'house' is down. Perhaps a small back up for essential core systems would be a good idea. Good luck. Henry | ||
| Doug Dickinson (Dougd470) (206.71.103.114)
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All good points. I too am interested in tankless if I can find a good one in Propane. That would resolve the recovery time issue (I like a good long shower once in a while). As for a propane generator - I will be using the generator a lot when traveling and do not want to "spend the room" for a much larger propane tank. I forgot about the 12VDC for the refer. I am going to re-think that a little - maybe keep the Vanner in the coach to supply a 12VDC battery bank. I like having the 24VDC for the inverter since it gives me backup for the starter battery (and jump starting a 24VDC coach is inconvenient in the woods. like we all say - whatever works for you is the right way. | ||
| David & Lorna Schinske (Davidschinske) (64.24.236.97)
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We knew someone with a tankless. They NEVER ran out of hot water. We are looking at the Aquastar by Bosch. It's supposed to be one of the best & runs on LP. I like to take hour long, really hot showers and I hate the bath houses in campgrounds. I know I can't take a long shower when boondocking, but I like hot showers and there's 4 of us all taking showers! I also want to put a tankless in my house to replace our 40 gal electric heater. It won't hold up to 4 showers in a row. | ||
| CoryDaneRTSIIIL (4.17.253.245) Rating: N/A |
I keep seeing comments about connecting the AC off of the inverter, which if the system is designed for this purpose, this will work great. I would like to also comment that when you are traveling down the road, an Inverter can feed your AC's from the bus generator on the motor. This would save fuel used on the genset during travel. Of course, your design my have purpose when using a generator to run the AC's rather than the inverter. Just another thing to be thought out while you convert, lol. cd | ||
| (Comet) (209.245.174.6)
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Just a quick note on tankless water heaters. I just installed a Takagi TK1 in my house with nat. gas upstairs to support a jetted bath tub (didn't want to drain the tank downstairs to fill a 60 gal tub). I chose Takagi because I felt it was a little better built than the Bosch and it also had a little better flow rate. I really like it and yes you can use propane, although you order a different part no. Things you should be aware of. I would not install one with small children using it. It can get very hot (140 deg) and there is no ability to regulate the temp lower except add cold water. Also, the adjustment is very touchy, and this takes some getting used to. Our knobs all have pointers on them, so we just kind of learned to remember where to point them for optimum temp. Otherwise it's kind of a crap shoot. Having said that, I would not trade it for a tank-and will probably add it to my bus -whenever I buy one | ||
| Bradd B. Smith (Bbsrtbusproject) (208.26.165.20)
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I have the Bosch Aquastar 125 with the battery ignition. The temp is easy to adjust, and the gas use rate is determined by the water flow. It does not use any power or gas as in a pilot light, except 2 d cells. They also make one to be used for re-circulating for hot water heat. It is a nice unit and I put one in my house, NG as well as my new "real" house, the bus, LP. As Fred pointed out, they are difficult to winterize and this could be a real concern depending on where you live. They do need to be maintained to operate correctly, but what does not? I am very happy with both of mine, got them brand new at half retail on e-bay. Count me in as would not trade mine either. | ||
| Peter Broadribb (Madbrit) (170.215.38.89)
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A warning on tankless water heaters. This subject was discussed some months back and still I have yet to find one that does not expressly state that they are not suitable for RV applications. The info on the Bosch 125 states: This product is not approved for manufactured homes(mobile home), recreational vehicles (RV) or boats. Reference ANSI Z21.10.3. This is not to say that you can't get away with using it , but I wonder why they would state this if there was not a problem. Maybe the unit could fail due to road shock fracturing some of the tubes.... who knows. Cory, when you run the a/c off the inverter, the bus engine has to work harder to power that huge alternator to feed the batteries and I bet it will use more than the half a gallon an hour that a genset will consume. Another point is that as you near your destination, you may well encounter traffic and slower moving situations. The motor will be revving slower and not supporting the inverter as well and you could also end up sitting in traffic jams consuming your house batteries just when you will be wanting them for the camping purposes that they are intended for. Nothing worse than arriving at the site with low batteries is there. The genset is one of the most expensive pieces of equipment one buys, so why not use it whenever one can. Peter. | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.164.175.11)
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Yea, a couple of items. The propane fired instant hot water heaters burn a great deal of propane to heat water sosss quickly. This means that the burners are quite large for the size of the overall unit. This also means that the dedicated vent stack to let all of this excess heat out has to be HUGE!! In cabin or mobile home installations the instant hot water heater vent stack can be the same size as IN A WOOD STOVE. Six inch diameter! Where such a large sized exhaust stack could even be installed in a coach conversion would be difficult at least and impossible at worse. Oh, it has been done, but is it a SAFE installation? All that heat has to go somewhere. The second subject is that if an invertor is feeding a roof AC unit while driving down the road, then the chassis engine alternator is feeding the batteries to feed the invertor. This is a LOT of amps, like almost 140! To make it worse, the batts may feed the invertor without help from the alternator until a partial discharge condition is established, then the alternator is really socked with a huge load. Is your alternator heavy enough? Anyway, sorry for the long post. Yea, tankless propane instant hot water heaters MAY work in a coach, but read the label---all that exhaust heat must go somewhere. And...road running an AC unit thru the invertor is hard on the main engine alternator. Thanks. Henry | ||
| George Myers (12.85.15.180)
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Back to the basic subject of the thread. While some appliances work well on 12 VDC, the ones that are used to make heat tend to be rather weak and very slow. ie coffee makers, electric pots, microwaves, toaster ovens, etc. My how we drift. | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
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Oh I don't know. In a way I was talking about 120 vac and 12 vdc stuff by discussing the problems of running a roof AC thru an invertor from batts rolling down the road. Kinda a little bit. However.....what does an instant propane hot water heater have to do with 120 vac vs 12 vdc? Not a thing. You are right. Sometimes my feeble mind gets carried away. Sorry. Henry | ||
| Doug Dickinson (Dougd470) (206.71.103.184)
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Actually, the wantering helped me. I forgot about the impact of not having 12VDC in my coach vs the ignition needs of a furnace. It's all power, isn't it. Anyway - I got a lot out of this one! | ||
| Stephen Fessenden (Sffess) (208.230.117.44)
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One reason to consider 12 volt or 24 volt fixtures is to allow the use of very low power 115 volt AC power sources without blowing fuses or having to switch off circuits in use. I just spent a week in a beautiful campground on Prince Edward Island that had full hookups but only 15 Amp service. Some sites shared a 15 amp service. Only spent $8 US a day. Even though my microwave operates through the inverter, turning it on would blow a fuse unless other circuits were turned off. Apparently my inverter did not cut in soon enuough. I do not have a remote control panel to reset it to cut in earlier. In any case, I was happy to have a lot that ran on 12 volts in that campsite. We used the three 12 volt roof vent fans as a lot when we dry camped in Newfoundland between campgrounds. It is easy in summer here in the South to think that you will always need to run the generator anyway, but there are times that you will be quite comfortable with only vent fans. Check the previous posts on battery EQUALIZERs for what I think is the best was to get 12 volt power from a 24 volt system. Now that I have equalizers on both engine and house 24 volt battery systems I had no battery troubles on a 2 1/2 mongth trip. | ||
| FAST FRED (63.208.83.247) Rating: N/A |
For the propane tankless water heaters, the simple solution to having NO temp changes when showering is to fit a FW water return. You simply allow the shower water to spray into a high return pipe that goes Back to the water tank , and Don't shut off the shower head. A plug in the return will keep it safer from contamination when not in use. Some of the early tankless units were VERY slow to adjust. FAST FRED | ||
| Don KS/TX (63.15.244.65)
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OK, my way was to eliminate battery powered lights and stuff, figuring that why do I need it? I had a great inverter with power sharing, needed it going to keep the house fridge cold, so why would I want battery lights? Worked out well. For hot water a 19 gal 110v is tops, all the hot long showers you ever want, and while going down the road you got more 110v than you ever could use anyway, so you got hot water when you stop for the night. A 15 amp cord will power the bus for months on end too. The only change I would make if I were doing it again, is to use a 6.5 Onan LP genset rather than the 9kw diesel I thought I needed. |
