Inverter / Charger Suggestions

[E350]

Ah Ha! So that's what that cigarette adapter thing for my laptop is called, a "DC to DC Converter" ! The label on it says that input is 10-15V 10A max and output is 20V 4.5A
I assume that LED LCD flat screen tvs are also direct current. So, does anyone know of an efficient LED LCD flat screen which comes with or for which I can buy a DC converter?
I am aware that this is a little bit of a thread hijack, so I apologize to the OP, my fellow paddler...
SYOTR

[BroncoHauler]

http://www.my12voltstore.com/12_volt_tv_s/79.htm

http://www.truckers-store.com/12-volt-f ... -with-dvd/

[E350]

Cool Herb! Another reason I don't need a big pure sine wave inverter!!!

[BroncoHauler]

Originally Posted by E350

Cool Herb! Another reason I don't need a big pure sine wave inverter!!!

Saw a number of them had built in DVD players too!

Herb

[Scalf77]

Originally Posted by 86Scotty

Dave, maybe it's my sick sense of humor but that pic made me laugh. Where the heck did you find that? It blows me away how quickly we can access a picture of practically anything instantaneously on this interweb machiny thingy. Good stuff.

Professor, I don't think you will regret that Tripplite.

I believe this one, or a similar model, was what SMB was using for awhile. Can someone confirm?

I agree with Eric, I have had my Tripplite for almost 10 years now, I plug in almost daily but I do use the inverter sparingly. The unit in my SMB is the RV2012 just the next step up power wise. I have found only a few items that did not work with the modified sine wave. Most things with a clock or timer will not be correct.
That said, if I was to get a new unit I would probably go the Magnum pure sine wave unit. I like their charging set points and algorithms and fact that they document them. I also like the fact that I could tap into their unit and monitor in multiple ways, but then I am kind of a geek in that department.

Originally Posted by E350

I am going to stumble into this discussion and cite to this link:


I probably will buy an inverter only. Probably the modified sine wave in the link above.*

And run a separate charger. **

Because my $2500 2500W Prosine Xantrex bit the dust and I never want a combo unit of anything again.

I am not sure that I would hold combo units at bay because of your experience with Xantrex Prosine, they are notorious POS. But, I can't really shoot down your idea of separate units, because it does have some merits. I believe the combo units make for a simpler install , and less connections, but that does come at a price that you have already mentioned.

As far power usage of larger pure sine wave unit, versus a smaller unit, it would really depend on the unit. Some of the smaller units efficiency factors are pretty bad, I think the key with any unit is to make sure that you only power it on when you actually want to use it. Sure their a various settings that put a larger unit in stand by, saving power but IMO just leave it off until you need it.

So again there is no compelling reason that you could not have two small inverters, again I would resort to simplicity of install and such, but that is not overly compelling. So I would say that it comes down to your preferences. It's your rig your money, and at the lower price of some of those units, you won't be out a lot if they go bad and you decide you don't like the setup.

-greg

[boywonder]

That twilight Zone episode was good for a few nightmares.......


I'm not an electrical guru, but I work with a few EE's every day and things tend to rub off. The output of MSW inverters, particularly the older style stuff with big EI transformers inside (like the Tripplites) resembles more of a square wave with the corners rounded than a true sine wave. The electronics (MOSFETS, etc) in these are older generation are slow and make a fair bit of heat. All that being said, they usually work just fine for most needs and the Tripp-lites appear to have a high overload rating for a relatively extended period.

The fact that they are slow make them sort of low-resolution as far as making sine waves, so instead of a smooth wave you get a facsimile of a sine wave that looks somewhat like a sine wave with a lot of steps (not smooth) or maybe a few steps.

The inefficiency of the transistors means that for a given power input, some fraction of that input power is being turned into heat, so that's why they have cooling fans. That's also why they have an idle current listed in the specs, and as most of us have figured out, larger units have higher idle current than smaller rated units, and they dissipate more heat.

Common AC to DC power supplies are either linear, where the sine wave just gets filtered with a few stages of capacitors and resistors, or switchers, which use transistors switching at very high speed to make somewhat clean DC. Switchers are more efficient than linear supplies so they also run cooler for a given wattage.

Clean DC is a flat voltage (there are no sine waves in DC); if there is any residual AC (sine wave) it can show up as hum in your audio, or other visual noise on your video, etc.

The newer generation of pure sine wave inverters use newer tech MOSFETs that are more efficient (less input power going to heat) and faster so that the wave looks like a real sine wave although it will have lots of tiny steps if you look close enough, much more hi-rez. I haven't taken any of the newer generation stuff apart, but it appears that they don't have (or need) big honkin' transformers in them, and that's probably why you can now get a true sine wave 1500W unit for around $350 or so, and the fact that many are made in China/Asia.

So if you can run your device from 12V instead of 110VAC, you save all of that energy lost as heat due to the inverter inefficiency.

E350, many LED backlit computer monitors come with power bricks and many of these run on 12VDC. Check out newegg and look at the product pics. Of course, monitors don't have TV tuners so YMMV.

[E350]

Scalf77, et al.:

What on the spec sheet would I look for to compare efficiency of the various inverters?

Also if you don't mind, any suggestions for a stand alone charger for a 250AH AGM house battery?

Wonderboy: I think I read somewhere that switcher inverters do not do well when powered by a generator. Does that make sense to you, have you heard that?

[Scalf77]

E350,
You would look for a spec on load efficiency, even better would be a graph, as it is not consistent across the power range, usually peaks about a 1/3 way into and tappers off. Here is where your idea of multiple units makes a lot of sense. If you have a 2000 watt inverter your efficiency would probably peaks close to 650 -700 watts. It would then tapper off slightly to the full power range. But, if you operate it below 650 watts. you are getting you worse efficiency numbers. Thus having a smaller unit to cover those devices would be a power savings feature.

When it comes to comparing a modified sine wave (its a modified square wave) versus a pure sine wave inverter even if you had units of the same efficiency curve, the modified sine wave will use more power on inductive loads. Because the output power is not really clean the devices using them generally use more power then they would to do the same task on a pure sine wave or shore power, possible up to 50% more.

The high frequency switching inverters are not as good in the low load range as the slow frequency switching inverters, they also have less surge capacity, are smaller, lighter , cost less and no acoustical buzz. So if you are powering units with a high surge start current, you would need to compensate and get a larger high frequency switcher compared to a low frequency switcher. If I was to have two I would have the low frequency switcher for my larger unit, and then carry a smaller high frequency switcher for low power band that the larger unit is not at its best efficiency. You really want to size to your devices that you are using.

There are no inherent problems with running a charger in a combo unit other then as you say, if one part breaks you have to replace both parts. I have not really looked into any stand alone chargers, so I really don't have any advice there. I hope this helps some.

Greg

[E350]

Thanks Scalf77. The reason for my initial post was to share my big spending big dissapointment experience with the OP and to suggest, in theory, another approach.
Apparently he has been well directed toward the Tripplites
I apologize for coming off as grumpy, because I stil am given that not only did I buy the Prosine 2500W Pure sine wave inverter which crapped out just after the warranty, but I bought the remote for it too.
But I get the benefits of buying a pure sine wave inverter. I just want as small a wattage pure sine wave inverter as possible for my needs, for as little money as possible.
But I always get confused, and then stop, when looking for one.
Here is one on amazon:

http://www.amazon.com/Power-Bright-APS1 ... roduct_top

It gets favorable reviews, but here is a poor review from a guy who seems to know what he is talking about:

"the end result of all this is...the APS1000 puts out 8.5 amps AC, maximum, at 116 volts, and at a frequency of 60.0Hz, while pulling 98 amps DC at 13 volts.

986 watts. That's it. There ain't no "peak". Any additional load makes the APS1000 shut down on overload. The tech spec sheet packed in the box says "1000W continuous, 1250W 20 minutes". No way it will put out 10.8 amps. Not even for two seconds, much less 20 minutes."

Would I spend more money on a higher quality 1500W pure sine wave inverter. Yes. But there does not seem to be any high quality ones out there that I can find.

[boywonder]

E350: Check out the Samlex stuff. I have one of their solar controllers and really like it. They have an inexpensive 1500w pure sine wave unit. If I hadn't picked up the 1000W used Prosine for cheap, I would have bought this:

http://www.amazon.com/Samlex-America-SS ... x+inverter

These include the remote, and have a decent warranty IIRC.

Samlex also makes a couple of higher quality units as well (2000W):

http://www.amazon.com/Samlex-America-SA ... x+inverter

http://www.amazon.com/Samlex-2000W-Pure ... x+inverter