Backup power solution?

[doliver]

Is there any chance this Duracell power pack would be effective in running a heater and powerhead for a few hours in case of a power outage?

http://www.amazon.com/gp/product/B000TKHMWK/ref=cm_sw_r_de_dp

In a topic last year there was mention of a "true sine wave" required to operate a powerhead, but college was a long time ago and I don't really know what that means other than the appropriate Honda generator that did it was a lot more expensive than the rest of them.

 

[GreshamH]

Think of it this way...

A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.

Other then having to plug that unit into your set-up every time, it looks just fine to me. The sign wave part only comes into play if you where going to continuesly power that unit via it's inverter, which at that price is a modified sign wave inverter most likely. Just run it off battery power and you'll be fine

 

[doliver]

Very cool -- obviously it's not as good a solution as a generator but seems a lot easier to implement if I can just carry it over to the tank and plug stuff into it when the power goes out.

The aquarium is really the only thing I care about having backup power for and if this unit could get me by for a few hours then it would put me at ease as we head into the stormy season.

 

[Gomer]

[quote author=GreshamH link=topic=5524.msg68755#msg68755 date=1229044938]
A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.
[/quote]

If it is anything like a DAC, that isn't the technically correct picture Most likely, the DC is converted to a sign wave by a series of stepping voltages. Think of stairs

digital sine over a true sine:

 

[Gomer]

[quote author=Gomer link=topic=5524.msg68769#msg68769 date=1229046814]
[quote author=GreshamH link=topic=5524.msg68755#msg68755 date=1229044938]
A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.
[/quote]

If it is anything like a DAC, that isn't the technically correct picture Most likely, the DC is converted to a sign wave by a series of stepping voltages. Think of stairs

digital sine over a true sine:

[/quote]

Most likely the "true sine wave" DC converters just have a "fast DAC" which makes the steps really small. As the steps get really small, the signal approaches a curve.

 

[phishphood]

Like an integral, right?

 

[Gomer]

Ya. Think integral. DC stepped sine wave is like using rectangles to find the area under a curve. A sine wave is when you set the lim dx-->0

 

[sfsuphysics]

[quote author=doliver link=topic=5524.msg68754#msg68754 date=1229044403]
Is there any chance this Duracell power pack would be effective in running a heater and powerhead for a few hours in case of a power outage?
[/quote]
How big is the heater?

Hard to tell according to the "spec sheet" on amazon, it claims 28 amp-hour, but says a 5watt phone can run 35 hours, which translates to about 1.5 amp-hours ..

If it's a true 28 amp-hour device it would run a 150 watt heater for 22.4 hours, however I'm guessing there's a massive due to the inverter.

 

[hooked]

this
http://www.steadypower.com/catalog/product_info.php?products_id=2080

plus one of these that I have on hand (soon to be 2)
http://www.jegs.com/p/Optima/758403/10002/-1

and some thing like this
http://www.topsalesdepot.com/bwadctoacpoi.html

what do you guys think ? I get a good deal on stuff like the transfer switch and have good batteries already. I use the deep cycle for power back up already , but have to drag it in the house and swap plugs around . It works but kinda of a pain .

 

[sfsuphysics]

Mikey I'd ditch the inverter simply because of...

# Waveform: Modified sine wave

This.

Especially if you're going to run pumps.

 

[GreshamH]

[quote author=Gomer link=topic=5524.msg68769#msg68769 date=1229046814]
[quote author=GreshamH link=topic=5524.msg68755#msg68755 date=1229044938]
A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.
[/quote]

If it is anything like a DAC, that isn't the technically correct picture Most likely, the DC is converted to a sign wave by a series of stepping voltages. Think of stairs

digital sine over a true sine:

[/quote]

Is the top not chopped flat? Your picture sure is

 

[Vincerama2]

Never mention this stuff to an audiophile ... tube amps, whateva!

(I'm not an audiophile, I just like to mock them)

V

 

[Vincerama2]

[quote author=hooked link=topic=5524.msg68844#msg68844 date=1229061784]
this
http://www.steadypower.com/catalog/product_info.php?products_id=2080

plus one of these that I have on hand (soon to be 2)
http://www.jegs.com/p/Optima/758403/10002/-1

and some thing like this
http://www.topsalesdepot.com/bwadctoacpoi.html

what do you guys think ? I get a good deal on stuff like the transfer switch and have good batteries already. I use the deep cycle for power back up already , but have to drag it in the house and swap plugs around . It works but kinda of a pain .
[/quote]

Doesn't the cost of all that stuff slowly approach that of a nice Honda genny? Or a cheaper one maybe?

I bought the one from Kragen, not the Honda... In fact I can't even remember the brand, but it was a good deal with a rebate that came out to $150. There was a big thread on it on this board I think. Mine is still in the box, because I'm lazy. But aside from the aquarium, I justified it to my wife as being able to run the fridge and, more importantly, the freezer full of milk for the babies.

V

 

[Gomer]

[quote author=GreshamH link=topic=5524.msg68892#msg68892 date=1229102536]
[quote author=Gomer link=topic=5524.msg68769#msg68769 date=1229046814]
[quote author=GreshamH link=topic=5524.msg68755#msg68755 date=1229044938]
A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.
[/quote]

If it is anything like a DAC, that isn't the technically correct picture Most likely, the DC is converted to a sign wave by a series of stepping voltages. Think of stairs

digital sine over a true sine:

[/quote]

Is the top not chopped flat? Your picture sure is
[/quote]

Yes but that is not what you described.

A modified sign wave looks like a normal wave, but with the upper portion flattened off. A true sign wave has no "chop" of the wave.

This is what you described. Literally a sine wave with a flat top:

 

[GreshamH]

Nit picker! You know I know what I am talking about and you also know to the laymen what I said makes sense

 

[GreshamH]

I'll be watching every post of yours like a hawk now Gomer, be prepared to makes some corrections or retractions :lol:

 

[Gomer]

heh.

but back on topic.

the top graph is what we want. It is a true sine wave. This is what AC (wall) power gives us. decent inverters can create a reasonable sine wave like the second graph (really good ones are hard to distinguish by everyday means). The third graph is for gresham because he is a hawk with flat top. The last graph is a bad DC inverted sine wave. crappy inverters can give a signal representative of this. This course stepping is what AC motors are unable to process right. Why, is a whole other discussion

 

[sfsuphysics]

There's a reason why inverters for solar setups cost so damn much, aside from the fact they work with kilowatts worth of power as opposed to hundreds of watts. Getting a nice clean sine wave ain't cheap.

 

[Vincerama2]

The clipped top is one of the differences between a transistor based amplifier and a vacuum tube amplifier. Just FYI.
Both are analog, but the transistor will clip.

The "true sine wave" versus "modified sine wave" would be sort of analogous to making a bowling ball out of lego.

V

 

[Vincerama2]

[quote author=sfsuphysics link=topic=5524.msg68936#msg68936 date=1229111769]
There's a reason why inverters for solar setups cost so damn much, aside from the fact they work with kilowatts worth of power as opposed to hundreds of watts. Getting a nice clean sine wave ain't cheap.

[/quote]

If you go solar, it's best to go DC as well, like all that camper-trailer equipment (fridges, lights, etc)

V