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| 19" TV power draw through inverter [message #114395] |
Sun, 06 February 2011 17:58  |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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After reading about Dan Gregg's TV and power draw, I decided to make some measurements of my own.
The TV is a two year old Vizio 19 inch flat screen, 120 volt AC input set. With a Kill O Watt meter (KOW) on line power, it takes 25 watts.
I hooked the TV up, through the KOW to a Xantrex 400 watt modified sine wave inverter I have, ran it from the battery in my car and measured the DC current draw of the inverter with a digital meter of fairly good quality.
Results:
1. Inverter on, but not hooked up to anything. DC input was 12.5 volts and .28 amps while the inverter was running. So, the watt draw of the inverter with nothing connected to it was 12.5 x .28 = 3.5 watts.
2. Inverter on, supplying power to the TV, also on. DC input was 12.1 volts and 2.86 amps. So, the watt draw of the inverter/TV combo was 12.1 x 2.86 = 34 watts. The KOW meter said the TV was taking 24 watts.
3. The inverter efficiency, at this low load of 24 watts for a 400 watt inverter, is 24/34 = .70 or it is about 70 % efficient overall. Considering the standby 3.5 watts is always there if the inverter is on, and subtracting that from the total draw of 34 watts you have a 24/30.5 = 79% efficiency. Not bad considering the inverter only cost $25. Also note that the inverter input voltage dropped .4 volts due to wiring and a very small auto battery supplying the power.
So, there are some numbers for my set and inverter.
Might give someone some ideas to think about.
No, I did not watch the Super Bowl. This was much more fun.
Rob Allen
former owner of '76 x-PB
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| Re: [GMCnet] 19" TV power draw through inverter [message #114405 is a reply to message #114395] |
Sun, 06 February 2011 20:46  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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so:
a 24 watt TV, uses 34 watts on 12 volts or a (10/24) 30% increase in power
required, or almost 3 amps (2.86) total.
So if you use the inverter to charge your computer, it is going to draw
about .5 amps,?
which means your 200 watt, solar panel (running about 1/4 output) will
require as many hours of direct sun as you run these little loads ;>)
good info
gene
On Sun, Feb 6, 2011 at 3:58 PM, Rob Allen <profmail@wildblue.net> wrote:
>
>
> After reading about Dan Gregg's TV and power draw, I decided to make some
> measurements of my own.
>
> The TV is a two year old Vizio 19 inch flat screen, 120 volt AC input set.
> With a Kill O Watt meter (KOW) on line power, it takes 25 watts.
>
> I hooked the TV up, through the KOW to a Xantrex 400 watt modified sine
> wave inverter I have, ran it from the battery in my car and measured the DC
> current draw of the inverter with a digital meter of fairly good quality.
>
> Results:
>
> 1. Inverter on, but not hooked up to anything. DC input was 12.5 volts
> and .28 amps while the inverter was running. So, the watt draw of the
> inverter with nothing connected to it was 12.5 x .28 = 3.5 watts.
>
> 2. Inverter on, supplying power to the TV, also on. DC input was 12.1
> volts and 2.86 amps. So, the watt draw of the inverter/TV combo was 12.1
> x 2.86 = 34 watts. The KOW meter said the TV was taking 24 watts.
>
> 3. The inverter efficiency, at this low load of 24 watts for a 400 watt
> inverter, is 24/34 = .70 or it is about 70 % efficient overall. Considering
> the standby 3.5 watts is always there if the inverter is on, and subtracting
> that from the total draw of 34 watts you have a 24/30.5 = 79% efficiency.
> Not bad considering the inverter only cost $25. Also note that the
> inverter input voltage dropped .4 volts due to wiring and a very small auto
> battery supplying the power.
>
> So, there are some numbers for my set and inverter.
>
> Might give someone some ideas to think about.
>
> No, I did not watch the Super Bowl. This was much more fun.
>
> --
> Rob Allen
> former owner of '76 x-PB
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
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Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] 19" TV power draw through inverter [message #114433 is a reply to message #114405] |
Mon, 07 February 2011 10:16 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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Senior Member |
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| Mr ERFisher wrote on Sun, 06 February 2011 18:46 |
so:
a 24 watt TV, uses 34 watts on 12 volts or a (10/24) 30% increase in power
required, or almost 3 amps (2.86) total.
So if you use the inverter to charge your computer, it is going to draw
about .5 amps,?
which means your 200 watt, solar panel (running about 1/4 output) will
require as many hours of direct sun as you run these little loads ;>)
good info
gene
|
Gene: My Apple Mac Book Pro takes about 60 watts to recharge, and does it in about 3 hours, depending on how far I have run the batteries down. Using about the same efficiency as the TV numbers, that means it would take about 90 watts input to the inverter, for 3 hours, for a total of 270 watt hours. A 200 watt solar panel will (in general) put out about 150 watts considering the battery charge losses and the general flat mounting position of most RV panels. So, 2 hours of output would more than completely recharge my Mac.
I use my MBP a lot in my current RV setup (trailer and Jeep tow vehicle) and have a small solar system on the Trailer. Along with the charge when towing, my two golf cart batteries never seem to get really discharged anymore in the summer, even with heavy computer use in the evenings. Shoulder seasons of spring and fall do tax it a bit more, as I need more power for the furnace and lights with more dark hours. I still seldom run my Honda 1000 watt inverter generator.
Rob Allen
former owner of '76 x-PB
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