| Author |
Message |
Norm Edlebeck (216.114.232.19)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 12, 2004 - 2:46 pm: | |
What's the scoop on modified sine wave inverters? I see them advertized a lot 4000 watts or so, at about $250. Do they work at all, or will they cause AC's, Electric Fridge or compressors to fail or what? I have no idea if they are good or not good. Could someone please give some input on this issue? Thanks in advance for all your help, both now and in the past. You guys are all great !!!
Norm Edlebeck MC-7 |
Bill 340 (166.157.114.101)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 12, 2004 - 3:55 pm: | |
Norm I have a foriegn inverter also, they work great, I have a 6500 surge with a 3,000 watt constant, It powers everything in the coach but roof air, Mine was $350, I had a smaller one in my last coach and loved it, Go for it, then buy a Battery charger at auto zone ad travel, update whenever, But yes the work great, Try Bobrowe.com. thats where I bought mine. Good luck Bill |
CoryDane RTSII (66.155.188.28)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 12, 2004 - 3:57 pm: | |
I think there is a string down the line here, do a search and get the full scoop.
Short version...
Modified sine wave is a "cut rate" version of ac power used for incandescent lighting, motors (some wont go) battery chargers, (if they can stand the square-wave).
Modified sine wave sometimes will not work well with electronics, causing a dimmer noise or static on tv, strange actions on the computer(if it will run at all)
On the air con, It probably will run, at a cost. The modified sine wave (square wave) greates heat do to loss of power, your windings will get hotter than normal and the compressor/fan wont have as much energy to run do to the loss. Heat=energy=energy loss for appliance.
In most cases, they run, just not well, but electronics sometimes have a sever problem with Mod sine wave power, some to the point of not working.
I thought I read were a modified sine wave square wave was changed when huge capacitors were added to the ac side to help make the square wave more rounded to emulate a normal true sine wave. The advantage of this is obvious, less power loss due to the square wave, less heat on your appliances, more power to your appliances for operation and better compatibility to electronics. Of course, capacitors can have their own "problems" as well as cost.
They say you get what you pay for so you need to really study what you are wanting to do then see if the application will apply to the inverter.
There will be plenty of responses here, thats what we are here for, from some that have used a small mod-sine wave to run the frig or lighting and never had a problem. They will admit, however, that the appliance runs much better on land AC or genset.
( Two dogs has a cage with a spinning wheel racing rats running after some hanging cheeeeeese that is just out of reach. Don't Tell Ethyl!) (JUS KIDDING BOUT THE DOGS!)
ALSO, the low priced Mod-sine wave inverters usually have no charging abilitys, and if they do, they are manual and of the type that has a switch for on and off operation, no monitoring of charge.
The Sine Wave Inverters "Trace 4024 comes to mind" has a complete monitoring on the charger and many many extras. (Caution, the newer Trace 4024n has new software and some of the monitoring has been removed. The old unit is still available.) But do go to a website and look at the manual to better understand the options.
The Mod-sine wave is a very simple, hard working inverter and does what it was made to do. Just be certain it will fill your needs without any problems.
"Imagine"
cd |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 13, 2004 - 9:48 am: | |
Corey's right, a modified sine wave inverter is simply a cheepo square-wave inverter with a little filtering added to make the square wave "appear" more like a sine wave. Usually the result is that the output looks (on an oscilliscope) like neither a square or a sine wave... it usually ends up looking like a giant mess. True to it's advertised name, it will have fewer harmonics than a pure square wave, but it's basically only a semantics game in the name of sales.
I won't parrot the rest of what Corey said because everything he said is correct. Truthfully, the term "Modified Sine" is just a bunch of bunk designed by PR people so they are able to sell you a cheap device by mimicing a good name....EXACTLY the same as calling a new housing development "Beverly Hills Farms" when the only relation it has to Beverly Hills is that it's 40 miles away in a different town.
Modified sine inverters are great for non inductive loads like lightbulbs, toasters and heaters, and...um... they'll do fine with brushed motor style power tools like electric drills, skilsaws ....and blenders & hairdryers of course...
But that's kind of where it ends. Like Corey mentioned, some people will report that they have no problem with other motorized things, and that may be true. TV's and stereos? Ya takes your chances.
Modified sine inverters put out a ton of RF noise... so much so that a 400 watt one I had made the datastorm satellite system I used to have totally inoperative, and made my onboard computer crash when it was running. The wireless mouse and keyboard quit entirely! And this was only a 400 watt unit.
The bottom line is that you'll do a lot better with a true sine inverter for many reasons- if you're going to build it in to your bus, save your money and do it right or do it another way. Nothing like having a plug that you don't have to think about what it is you're about to plug in to it.
I carry a 1000 watt modified sine unit that has a couple big jumper clips on it, but ONLY for that occasion where I need a power tool where there's only a 12 volt battery nearby. I use it once every three years or so...
Ya get what ya pay for....
Cheers
Gary |
Johnny (63.186.169.192)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 13, 2004 - 10:56 am: | |
Wouldn't it be easier (and way less money) to run 12V stuff? Stereos & TV's are easy to find in 12V, & don't most laptops run 12V power? |
CoryDane RTSII (66.155.188.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 13, 2004 - 6:24 pm: | |
Laptops run on 19vDC and have a low voltage cutoff at about 18.9vdc, at least mine does.
The power supplies are regulated to keep the proper voltage input to the laptop. Too much can damage it as can too little.
They do make 12dc to 19v dc converters that the laptops run fine on.
Electronics are more particular of their voltage and quality there of than are lites or motors.
"Imagine"
cd |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 13, 2004 - 9:52 pm: | |
Johnny, "my way" says YES YES YES to your question.
I started my bus as a combination 120 / 12 system, but very quickly realized that at least for me, 12 volts was the way to go. 12 volt inverters for the fluorescent lights, 12 volts for the stereo, 12 volts for the LCD monitor that doubles as a TV, backup camera, and GPS display, 12 volts for the water pump, exhaust fans.... basically 12 volts for everything.
I have a 7.5K onan that I run when I want A/C or the microwave oven, etc, but I personally can't imagine wanting an inverter other than the tiny 100 watt sine wave one I use to power my computer (which draws 15 watts full-on, max) and the occasional charging of a cell phone. The tiny inverter is also plenty to run my laptop power supply, and it draws so little power that I leave it on 24/7.
Everyone has their quirks...I know a lot of guys love their giant battery banks and monster inverters because they hate propane. I carry 110 gallons of the stuff, and only four T-105's for my 12 volts. Another cool thing about the 12 volts the way I did it, is that when I'm plugged into shore power, I have a 75 amp converter that seamlessly takes over for the batteries and also charges them. It's neat having NOTHING to change when I unplug, and I don't even have to flip any switches!!!
Jes' my way.... |
Gary McFarland (Gearheadgary) (68.79.120.182)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 13, 2004 - 10:40 pm: | |
FYI Toshibas use 15V. They vary from brand to brand, but--same deal as what you said.
Gary |
Johnny (63.186.209.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 14, 2004 - 12:01 am: | |
Mine will be 100% 12V, including the roof A/C units. The only 120V will be the converter for shore power. I'm planning 6 T-105 batteries. |
Gary McFarland (Gearheadgary) (68.79.120.182)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 14, 2004 - 9:22 am: | |
What is the 12V roof airs you will use?
Gary |
CoryDane RTSII (66.155.188.105)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 14, 2004 - 10:01 pm: | |
My coach is also 12 / 120v, but I need to explain...
The windows have a halogen lamp in the middle, it lights the coach and indirectly by bouncing light off the blinds.
The Halogens are on a timer with dimming ability (BSR) and works when on ac (Intended to be used when on land power but will work on Inv/Gen). If traveling, a switch will turn on the hallogen on 12vdc.
The ceiling florescents also work on bi power, when on shore power, they are supplied by the AC transformer, (Inv/gen able), when bus is running, can be turned on with bus DC power. Bed room has a ceiling lt that is 120vAC, when no ac available, two wall lites work on 12vDC.
My intention was to keep lighting load off the battery as much as I could and use inv/gen power on demand or by choice.
My system is sort of like Gary Stadlers, only different. LOL
Actually, I tried to mirror the RV electrical system, since they were tried and true but I added some refinements.
Hope that helped
"79 RTSII"
cd |
Johnny (4.174.109.102)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 15, 2004 - 1:10 am: | |
Do a search for "12V roof A/C" and you should find them. |
FAST FRED (4.245.212.57)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 15, 2004 - 5:44 am: | |
The only hassles I can see with 12V roof top airs is the battery charger to operate 2 at once from shore power will be really expensive.
Also the battery bank would have to be huge , as would the charging system to operate one overnight on batts alone.
This is because the discharge RATE (as well as DEPTH ) factor into battery srvice life.
FAST FRED |
Johnny (4.174.91.34)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 15, 2004 - 11:32 am: | |
I don't plan to run mine on batteries at all. Either shore power (not often) or a 12V genset. |
FAST FRED (4.245.230.53)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 15, 2004 - 2:07 pm: | |
What will you use to provide the DC volts while at the power pole?
Its gona be one heck of a big charger (150A 14v DC output), and may cost as much as an inverter.
FAST FRED |
Johnny (4.174.106.226)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 15, 2004 - 7:15 pm: | |
Either one huge charger or maybe two or three smaller ones (one per roof A/C). Worst case: run one A/C at a time.
I don't use the PP very often. |
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