| Author | Message | ||
| Barry McCully (Turtle)
Registered Member Username: Turtle Post Number: 6 Registered: 8-2007 Posted From: 71.7.185.171 Rating: N/A |
I want to purchase an inverter but don't know what size to get.Does anyone know is there a chart to tell how much power appliances take. Thanks | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 656 Registered: 12-2000 Posted From: 76.1.180.218 Rating: N/A |
I have seen charts, but do not remeber for sure where I saw them. I think Dave Smead's books have charts in them. What I did was look on the tags on the 120 volt appliances that we planned to run off the inverter (i.e. TVs, Microwave, coffee maker,hair dryer, etc). The tags will give either watts or amps. If it list amps take that number times 120 (volts) to get watts. Add up all the watts for a total watts needed. Then you have to decide if all of these will be used at the same time. If so, you need an inverter slightly larger than the total watts. The other option is to use a smaller inverter and practice "Power Management", making sure you never turn on enough appliances at the same time to exceed the capacity of the inverter. We purchased a 2500 watt inverter and have had no problems. Jack | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 524 Registered: 7-2006 Posted From: 66.217.106.217 Rating: N/A |
Appliance Power Chart 1 appliance power chart 2 appliance power chart 3 Take yer pick, they're all not too bad.... | ||
| Ed Roelle (Ed_roelle)
Registered Member Username: Ed_roelle Post Number: 40 Registered: 3-2005 Posted From: 68.85.142.109 Rating: N/A |
One additional point. As inverters work, they heat-up. As temperatures rise, inverter capacity is reduced. That is partially why a 4000 watt inverter usually will not run 2 air conditioners driving down the road. Ed Roelle Flint, MI | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 675 Registered: 1-2003 Posted From: 72.171.0.147 Rating: N/A |
"... why a 4000 watt inverter usually will not run 2 air conditioners driving down the road ..." Hey, Ed -- Don't tell my 4KW inverter! (It doesn't know it's not supposed to do that.) Seriously -- We run two AC's on the inverter frequently, along with all the other stuff that's on all the time (computers, routers, file server, and all the phantoms like clocks on the coffee maker and microwave). And one of the two is a hard-starting custom split system that draws 15 amps running (as opposed to my roof units, which draw about 13 apiece). But then again, we have a "true" sine wave inverter, which, when it comes to running motors like the ones in AC units, makes all the difference. If you're planning to run air conditioners or a household-type, compressor-operated refrigerator, it's worth the extra money to get the sine wave inverter rather than an MSW model. You'll use less juice, the inverter will run cooler, and your appliances will run cooler and last longer. FWIW. -Sean http://OurOdyssey.BlogSpot.com | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 166 Registered: 8-2004 Posted From: 12.77.64.36 Rating: N/A |
Sean Welsh said "it's worth the extra money to get the sine wave inverter rather than an MSW model." Sean, What about two inverters? One (less expensive) MSW for the coffee makers and lights and one PSW (suitably sized) for the things that need it. It seems to me that it might save money to do it this way - or, it might be smarter to just invest in a PSW for everything. What's your take? | ||
| Jerry Liebler (Jerry_liebler)
Registered Member Username: Jerry_liebler Post Number: 288 Registered: 3-2005 Posted From: 67.141.38.141 Rating: N/A |
There also is an extreemly important, to me certainly, difference between the Trace SW2512, SW4024 and almost all other inverters. This vital, to me, feature is the ability to simultaenously limit power taken from a shore cord, and use battery power for needs above that limit. Thus I can plug into a 15 amp shore cord and start loads that take way more than 15 amps. These inverters also automatically start a generator if the battery voltage gets too low. These features, to me, justify the price difference. Regards Jerry 4107 1120 | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 676 Registered: 1-2003 Posted From: 67.142.130.16 Rating: N/A |
Bruce, On the subject of two inverters -- I don't think you'd save any money by having two, once you've decided to have a sine wave model big enough to run an AC. The difference in price between, say, a 4KW sine wave and a 2.5KW sine wave is probably less than a 1.5KW MSW, or at least pretty close. And the flexibility of having the full 4K available for the non-inductive loads, if needed, is a bonus. That being said, if you have a 12-volt coach, you may find that you simply can't get a single inverter big enough for your needs. We have a 4KW continuous, 8KW surge unit on our 24-volt coach, and we've used the whole capability on a number of occasions. But 3KW is about as big as they come for 12-volt models. If you have a 12-volt rig, and you want more than the 3KW that a single unit can provide, you might save a few bucks by buying, say, one 2.5KW SW, and one 2KW MSW. That does limit the size of any single load, of course, whereas buying a pair of 2.5KW SW units that have a sync cable would give you a full 5KW available for even a single load. FWIW. BTW, I agree with Jerry. We use the load supplementing capability of our unit all the time. The poor-mans way to do this, BTW, is to buy a plain inverter (with no charger) and a separate multi-rate charger that can be dialed down. -Sean http://OurOdyssey.BlogSpot.com | ||
| Jerry Liebler (Jerry_liebler)
Registered Member Username: Jerry_liebler Post Number: 289 Registered: 3-2005 Posted From: 67.141.38.141 Rating: N/A |
I'm cursed with a 12 volt bus, so I didn't have the option of a 4KW inverter. But I've found that the 2500 watts of the SW2512 is enough. While I'm driving I can be running: My front AC unit @ 1500W, My refrigerator @ 120 W, a TV that wife is waching @ 165 W. A couple of times we've also run the microwave that draws 800 W and it's not tripped the overload. What Sean said about appliances lasting longer with true SW inverters is certainly true. I used to have a S&S with a MSW inverter and it ate 2 microwaves in the course of a year. Since I have limited inverter capacity all my lighting is 12 volt and my satellite receiver is also 12 volt. Regards Jerry 4107 1120 Regards Jerry 4107 1120 | ||
| Jerry Liebler (Jerry_liebler)
Registered Member Username: Jerry_liebler Post Number: 290 Registered: 3-2005 Posted From: 67.141.38.141 Rating: N/A |
Sean said "BTW, I agree with Jerry. We use the load supplementing capability of our unit all the time. The poor-mans way to do this, BTW, is to buy a plain inverter (with no charger) and a separate multi-rate charger that can be dialed down. " I like the idea, but it breaks because there simply is no charger that allows one to limit the input curent. Also to supply the 2500 W @ 12 volts would mean a charger capable of 220 amps or so, it might be cheaper to get an SW2512. Similarily for a 24 volt system one would need about a 175 amp 24 volt charger and again the SW4024 looks like a bargin. Regards Jerry 4107 1120 | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 677 Registered: 1-2003 Posted From: 67.142.130.48 Rating: N/A |
Jerry, The multi-rate chargers of which I am thinking have user-selectable output rates, which effectively limits the input current as well. But you are right -- they are not available in high-current ratings. So you would be limited to, say, 100amps. Still, if the objective was to run a whole coach on a single 15-amp circuit this would do the trick. -Sean | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 788 Registered: 11-2004 Posted From: 72.91.168.92 Rating: N/A |
" because there simply is no charger that allows one to limit the input curent. Also to supply the 2500 W @ 12 volts would mean a charger capable of 220 amps or so," TRY the Vanner 3600W twin inverter - HTH | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 195 Registered: 2-2001 Posted From: 69.77.155.72 Rating: N/A |
ACTUALLY..... The poor man's way to do this is no inverter & run the 6KW genset when AC power is needed. This method has worked fine for us for about 15 years. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 678 Registered: 1-2003 Posted From: 72.171.0.144 Rating: N/A |
"ACTUALLY..... The poor man's way to do this is no inverter & run the 6KW genset when AC power is needed. ..." If we did that, we could have paid for our entire inverter installation twice over by now just on the diesel alone, let alone the other maintenance items required to keep a genset going. So I would hardly think that counts as a money-saving strategy for folks in our situation. I would have to guess you have a very different usage pattern than we do. For an average 5-8KW diesel genset, here are some rough guidelines for cost-of use: (all numbers are per hour of runtime) Amortization: $0.50 (~$5,000 per 10,000 hours) Fuel: $1.50 (~1/2 gal @ $3.00/gal) Oil & Filters: $0.20 (~$40 per 200 hours) Misc. Maint.: $0.05 (about $25 per year) ===== Total: $2.25 per hour Less than 1,000 hours of run time will buy you the best inverter on the market, plus all the fixin's. (Yes, I know there are other costs, such as batteries which need to be replaced periodically, etc., but, when you do the math, inverters tend to pay for themselves pretty quickly.) We put 300 hours a year on our genny -- and that's with a 4KW inverter on board. Without the inverter I can easily see us running well past 1,000 hours per year -- especially if we'd need to run it while driving to keep the upstairs AC on. Then there are the times when you just can't run a generator. In a campground where, for example, the input power is inadequate to run your air conditioning, but generator use is prohibited. Or at national and state park campgrounds with no power at all, where park rules limit generator use to certain hours of the day (or prohibit them completely, such as Texas Springs in Death Valley). It really pays to take a hard look at how you will use your coach, and then spend some time crunching the numbers. Sometimes, ferreting out all the numbers can be a challenge. But analysis like this can help in planning and sizing your generator, inverter, and even solar and wind power, or, for that matter, whether it pays to spend the night in a $30 RV park instead of the local Wal-Mart. FWIW. -Sean http://OurOdyssey.BlogSpot.com | ||
| Rick Johnson (Plywud)
Registered Member Username: Plywud Post Number: 7 Registered: 9-2007 Posted From: 76.104.236.71 Rating: N/A |
This was my train of thought as well, inverter running off a 250A alternator was free power. It's not in the true since of the word. I loose about 10% of my overall horsepower and fuel economy under full load. While I only deal with that in the summer time heat if I enter that environment, the point is that there is a price to pay for that engery source. We live in a fairly mild climit, PNW, and even if we have been boondocking for the week-end, I give up some fuel economy on the return trip to recharge the house batteries and keep everything else alive. Now maybe it's because I only have 6V71 to support the big altanator, but I think these things are relative, 238 horsepower 25K lb coach, 450/500 horsepower 50K lb coach. while the cost is not so relative to me, if I lived in the south it would be more of an issue, at least during the humid months. The trade off of horsepower might make the generator solution more appetitezing in a mid west head wind if you know your only giving up a gallon a hour in fuel economy. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 680 Registered: 1-2003 Posted From: 67.142.130.32 Rating: N/A |
Rick, I've measured it... ~150 extra amps from the alternator to the house system (= ~4KW) costs me about 0.2 gph on the big Detroit. By contrast, my generator runs a full gallon an hour for the same effect. No question that it is cheaper to rob some BHP from the main engine. Of course, my genny is a big 15KW (continuous) unit -- you'd run only about 0.5-0.8 gph on a more suitably sized set. But still, that's a lot more than 0.2 gallons. -Sean http://OurOdyssey.BlogSpot.com | ||
| Stephen Fessenden (Sffess)
Registered Member Username: Sffess Post Number: 717 Registered: 1-2002 Posted From: 66.38.120.219 Rating: N/A |
The inverter allows you to time average 120 volt loads on 15, 20 and 30 amp hookups. being able to use the lower power hookup could save you $2 a night in some campgrounds and might mean the differnce between being able to stay there or drive on. | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 186 Registered: 7-2005 Posted From: 152.20.216.103 Rating: N/A |
One issue I have is that the 4024 (and 3624) inverters don't have enough pass-through switching capacity. I'd rather not have two breaker panels. I have my AC panel mounted on the side of a kitchen cabinet so I can turn off loads as required. This give the flexibility to run any circuit on inverter, but not all at once (obviously). Currently, I have 1000 watt 24 volt inverter that I plug the 50 amp cord into when I want to use the inverter. If I need more power, I start the generator and have 6500 watts after 30 seconds (auto transfer switch). I'd really like to 1) be able to charge the batteries from the inverter's charger when the engine is off and the generator is running. 2) charge batteries when plugged into an outlet and 3) use the load supplementing feature when on less than 50 amp shore power. From what I've found, there isn't an inverter that will accomplish all this... at least as it's designed. Even having two inverters won't accomplish this, as the pass-though capacity is generally limited to 30 amps. Does anybody have any suggestions, other than just using a separate charger for charging the batteries and plugging the shore cord into the inverter while not on a power pole? Thanks. David | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1083 Registered: 12-2000 Posted From: 74.12.84.76 Rating: N/A |
Hello. The #1 sellling point for my Trace 4024 was its ability to limit the draw from shore power. Been involved with too many high draw applications at work that can't be plugged into a 15 amp plug because it will trip the breaker without ruthless load shedding and supervision. The Trace is absolutely fool proof, kid proof, wife proof, and stupid husband/busnut proof. You never know when running a 100' extension cord from a house will be your only option.... (tip: best to set the limit to 12-13 amps when on the other end of that 100') happy coaching! buswarrior | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 681 Registered: 1-2003 Posted From: 67.142.130.21 Rating: N/A |
One issue I have is that the 4024 (and 3624) inverters don't have enough pass-through switching capacity. ... I'd really like to 1) be able to charge the batteries from the inverter's charger when the engine is off and the generator is running. 2) charge batteries when plugged into an outlet and 3) use the load supplementing feature when on less than 50 amp shore power. ... there isn't an inverter that will accomplish all this... Even having two inverters won't accomplish this, as the pass-though capacity is generally limited to 30 amps. David, The pass-through capacity of the SW4024 is 60 amps (at 120 volts). I have my 4024 output protected by a 60-amp breaker. And this inverter, in our application, does all three of the things that you mentioned. The only downside we found, and we just worked around it with some relays, was the fact that the internal transfer switch is single-pole. A three-pole would have been ideal, and even a two-pole would have been better than the single. Also, I'm not sure how Buswarrior's unit is husband-proof -- I find the ancient menu interface to be very clunky, and more than once I've set the wrong variable or forgotten to reset one. But, for what it does, I can live with the bad ergonomics. Long description of how we worked around the lack of extra poles in the transfer switch is here: http://ourodyssey.us/bus-e-ats.html -Sean http://OurOdyssey.BlogSpot.com | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 168 Registered: 8-2004 Posted From: 12.77.66.18 Rating: N/A |
OK, for somebody who can only find black magic in electrons, can someone explain what "pass through capacity" is? How is a SW4024 wired - both input and output? And, what does it DO???? Bewilderdly yours, BH, NC USA | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1084 Registered: 12-2000 Posted From: 74.12.84.87 Rating: N/A |
Sean, you'd be best to answer Bruce's questions. 4024 is "me proof" because I leave it all at default settings, adjusting source amps as needed and otherwise, hope for the best!!! If I don't try to use all of it's complexity, I stay out of trouble? Tongue somewhat in cheek, happy coaching! buswarrior | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 682 Registered: 1-2003 Posted From: 67.142.130.39 Rating: |
Buswarrior, I change a few settings fairly regularly: AC1 Input Amps. This is the shore size, and, on my non-MC model, I actually have to scroll all the way down to menu 8, then press the red and green buttons simultaneously (and it's really picky about this -- I only get it right about four out of five times) to get to menu 9, then scroll down to menu 11, then scroll through menu 11 to the AC1 setting. What a pain. I also change the Absorption Time. When we are boondocking for a while, I'll set it on one hour or less, to keep the genny run time down. After that first hour, the rate at which energy actually goes into the batteries is very low, so not much bang for the buck running the big genny. Once we get back to a power outlet someplace, I set the absorption time back up to 3 hours. This gives us the best "top off" of the batteries from a fixed-fee source. Of course, this setting also requires the double-button-press nonsense described above. Of course, generator On/Off/Auto is another control we use all the time, and sometimes I leave it in the wrong place (off vs. auto, for instance -- after running the genny manually, you need to select "off" to shut it down, and then you have to remember to move it to "auto" again if you want the autostart feature). Fortunately, this control is one-button access. I've also been known to manually dial the Max Charge Amps AC down, when inverter overheating may be a problem. Also, in really hot weather, I have sometimes dialed the AC-2 amps down a bit, to keep that wiring from frying. OK, as for Bruce's questions: It may seem innocent, but this is a big one to tackle. That's because we all use the term "inverter" to talk about things that are sometimes only inverters, but often much more than that, too. The most basic kind of inverter does nothing else: it accepts DC voltage as an input and produces AC voltage as an output. Inverters made for vehicles in the US commonly accept 12 or sometimes 24 volts DC (nominal) input and produce 120 volts AC output. The size of the inverter, usually specified in watts and rated for continuous use, sometimes with a higher "surge" rating for specified shorter periods, will determine how many amps of AC current it can supply, and this in turn will determine the amount of DC current needed to operate it at the rated capacities. Incidentally, these capacities will also determine the sizing of both the AC output wiring and breakers, and the DC input wiring and fuses, and will also dictate, to some degree, what kind of battery plant you will need. This type of inverter, with one DC input and one AC output, is probably the least-discussed here on the boards. They are useful if you have an existing, fully-equipped RV with a separate battery charger (usually part of a "converter") and all you need to do is add a couple of AC outlets that will run from the batteries. Inverters of this type are available in the widest range of capacities, from little 20-watt units that will plug into a cigarette-lighter type outlet and provide enough juice to, say, run your laptop, all the way up to units that can run entire office buildings. So if you need a really small inverter, or a really large one (larger than any coach could need), this is what you will end up with. In many high-end RVs and bus conversions, it is common to use inverters which include built-in battery chargers. These devices are more properly called "inverter/chargers," but most of us are too lazy to type all that (self included), and we just call them "inverters." The addition of the charger function means two things: 1) The DC cabling is now bi-directional. What was just an input on a plain inverter is now an input/output. Generally, the DC capacity of the battery charger is much lower than the capacity of the inverter, so the wire sizing is usually not impacted by this additional function, although it may have a bearing on just exactly where in the circuit you put the fuses. 2) There now needs to be an AC input to the unit, in addition to the AC output, in order to provide power to the charger. For a lot of safety and regulatory reasons that I will not delve into here, the AC input source must be separate from the AC output wiring where the inverter supplies power when running on batteries. So an inverter-charger has one set of DC connections, but two separate sets of AC connections -- an input, and an output. Now, the battery charger and the inverter are actually separate circuits, conveniently located inside the same box. So you could just leave it at that -- for example, a 120-amp battery charger on one side, with a 10-amp power cable coming into it, and a 2400-watt inverter on the other side, with a 20-amp power cable coming out. Any time the output draw exceeds the input draw, the batteries will be draining, and when the output draw is less than the input, the batteries will be charging. It's easy to see the problems with this arrangement: (1) You'll be draining the batteries any time the output outstrips the capacity of the battery charger, even if the input source has the capability of providing the full amount of current needed and (2) there are efficiency losses associated with both the process of turning AC into DC for the charger, and also in the process of turning DC back into AC in the inverter. With this arrangement, you are needlessly going through both losses, generating heat in the process. Consequently, almost every inverter-charger includes a built-in "bypass" relay. There is still a separate AC input and output, but when the unit detects power available at the input, it closes the bypass relay, passing the input power directly through to the output. The battery charger also remains connected to the input. When the bypass relay closes, the inverter section becomes idle. Most good units will then automatically "shut down" the inverter section so that it is not even using what we call "idle current." The capacity of the unit, in AC amps, when operating in this mode depends on the size of the AC input and output wiring, terminals, etc., as well as the capacity of the bypass relay (sometimes confusingly called a "transfer switch," by inverter manufacturers). This capacity may be greater than, less than, or equal to the rated output capacity of the inverter. This is what David was referring to when he wrote about (and I responded about) "pass through capacity." As an example, the Trace SW4024 will pass through a full 60 amps of AC current continuously. That equates to 7,200 watts of power, which is a good deal more than the rated continuous output capacity of the inverter itself (4,000 watts), but still less than the rated surge capacity (8,000 watts). This is the reason, BTW, that Trace/Xantrex recommends a 60-amp output breaker downstream of the unit. Many modern inverters with integral chargers and bypass relays also have fully adjustable charge rates, and can lower the battery charger draw as output draw increases. In the 120-amp (DC) charger example, the AC draw will be as much as 11 amps. If you tell the unit's control microprocessor that only 30 amps of input power are available, and it measures, say, 25 amps of AC being used at the output, it will lower the charge rate down to ~55 amps DC so that the battery charger uses only the remaining 5 amps of AC power, thus keeping you within the 30-amp budget (and, presumably, keeping the 30-amp breaker on the campground pedestal, or your genny, from tripping). As if all this has not been complex enough, there is another whole category of inverter-chargers, that have the capability to completely synchronize their AC output to the waveform of the AC input. These inverters are designed, tested, and approved to actually supply AC power backwards through the input wiring (remember the safety and regulatory issues I mentioned above?), with special circuitry to detect loss of input power and instantly cut off this backward flow. This is to prevent the inverter from trying to power an entire neighborhood back through the input in the event the grid power is lost. It also protects power company personnel working on the lines. Because these so-called "grid-tie" inverters can synchronize their waveform, they can perform an additional trick -- they can "add" power from the inverter section to the output, even with the bypass relay closed, when the output demand exceeds the input supply. That's the capability that Jerry (and I, and others) was raving about above. It's expensive to add the synchronization and instant backfeed-cutoff capability to build such an inverter, and so they are not typical features of RV inverter-chargers. The exception is the Trace SW series, which was really built for grid-tie use, then adapted to the RV market. Now there's one final piece of confusion to add into the mix. Once you've built an inverter/charger with a bypass switch, and a separate AC input and output, it's actually fairly easy to add a second relay so that there can be a choice of two different AC inputs instead of just one. So you can have both a shore power or grid input, as well as a generator input. This is the capability that most folks refer to as an "internal transfer switch" -- to transfer from shore to generator or back. Not to be confused with the simple bypass relay that some manufacturers advertise as a "transfer switch." So to answer your "how's it wired" question, a Trace SW4024 has the following main wiring connections:
AC-1, AC-2, and the AC output all share a common neutral connection and a common ground connection. The common neutral leads to certain installation challenges if you want to use both AC inputs, but that's another discussion. I hope this clears some things up for you, rather than just adding to the confusion. -Sean http://OurOdyssey.BlogSpot.com | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 171 Registered: 8-2004 Posted From: 12.77.112.140 Rating: N/A |
Sean Welch wrote: "I hope this clears some things up for you" Very much, thank you! BH, NC USA | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1086 Registered: 12-2000 Posted From: 74.12.84.122 Rating: N/A |
Excellent report, Sean! Yes, the red/green button simultaneous push is a pain. I put up the cash for the SW 4024 so I wouldn't need to upgrade the hardware later. I just need to upgrade the wetware.... happy coaching! buswarrior | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 188 Registered: 7-2005 Posted From: 152.20.216.103 Rating: N/A |
Sean, Thanks for the extensive posts on inverters. What I should have said / meant to say is that most of us have 120/240 volt systems and, short of having a 2nd inverter or 2nd breaker panel, etc don't have an easy way to connect the single-pole inverter to the two legs of AC power. I'm sure there is a custom solution, such as using relays when only one leg is present (like an 120V/30A outlet) to break the second leg (before the inverter) and connect it to the first leg being supplied to the inverter. I guess what I'm looking at is almost an ATS for leg 2 of the AC power input to switch between shore cord or inverter, while leg 1 is always fed from the inverter. David | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 683 Registered: 1-2003 Posted From: 72.171.0.147 Rating: N/A |
David, That's pretty much what I built, although I added some extra features. Probably cost me $100 in parts, including the main transfer switch. Description is here: http://ourodyssey.us/bus-e-ems.html I've got my water heater, one of the three roof airs, the electric stove outlet, and the electric heat on the "switchable" panel. One 30-amp DPDT power relay, about $15 (although I had a bunch lying around) does the switching. When we are on a full 50-amp shore feed, or the genny is running, all those loads are on leg 2. When we have a 30-amp shore feed, those loads are on the inverter, where they get the benefit of the SW4024's load-support feature. And when we have no AC input power at all, they are just dead. A simple SPDT, center-off toggle switch allows me to override in either direction: I can power those loads from the inverter, even if there is no input AC at all, or I can force them to "leg 2" even if it's not hot (meaning they will be off even though there is power coming into the inverter). We rely quite a bit on this particular relay. -Sean http://OurOdyssey.BlogSpot.com |
