Power consumption of CRTvsLCD - AVS Forum
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post #1 of 12 Old 05-30-2011, 02:45 PM - Thread Starter
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I have been researching a lot on power consumption of crt vs lcd these last years (TV technician) . I have reached this conclusion: energy saving companies (ex. Energy Star, energysavers.gov) grossly overrate the power consumption of crt monitors. (and lcd monitors)
For example:
HP p930 CRT monitor 19"
rated +- 120watts
TRUE watts (tested with amp meter. watts=Volts x Amps)
122.8V(line ac) x 0.4A(average) (0.3A Min - 0.5Amax (dark scenes, white raster) = approximately 50 watts average
Cost per year at 5 hours a day 70 days a year (8.5c per kwH example)
=1.48$

These companies rate these monitors at 150 watts average. Thats triple the average true watts. That would add up 4.46$ a year.
To compare:
LCD Monitor Generic 19 inch
true wattage 0.2A x 122.8VAC = average 28 watts
that amounts to 0.833$ per year.
So you save 0.647$ per year (if you pay 8.5c per KwH)
Are the companies trying to make us change monitors or something? Is there really a need to change to LCD just for a drop of less than a dollar per year. OR are the people who test these monitors just incompetent. Just to compare an average samsung 32inch LCDTV takes a wallop of 200W constantly on your electricity (at max backlight, where people usually watch the TV)
A 32 inch CRT TV (sanyo) takes an average of about 120watts ( from 70watts to 140 watts max (bright scenes, etc))
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post #2 of 12 Old 05-30-2011, 03:15 PM
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Yes CRTs actually are pretty power efficient. I tested my built in May 2006 Toshiba 30HF66 (purchased new in 2008) which is calibrated for a totally dark room (low contrast setting) with a Kill-a-watt power meter and it averages around 80 watts fluctuating based on screen brightness. This is a 30" 16:9 set. Pretty sure this set is more power efficient than most LCDs in this size range available today. Don't drink the slim is better kool-aid it doesn't taste very good


p.s. The stated power rating on this set is 195 watts which it doesn't come close to at least not with lower contrast settings. My guess would be that stated ratings reflect maximum settings and maximum sound level.
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post #3 of 12 Old 05-30-2011, 03:39 PM
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Also I remember reading on Wikipedia on the CRT page that CRTs had the lowest power consumption per screen inch but it must have been edited/erased as it no longer says that. Not sure if completely true or not but seems entirely plausible to me.
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post #4 of 12 Old 05-30-2011, 05:15 PM
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Quote:
Originally Posted by hoffo View Post
Pretty sure this set is more power efficient than most LCDs in this size range available today.
p.s. The stated power rating on this set is 195 watts which it doesn't come close to at least not with lower contrast settings. My guess would be that stated ratings reflect maximum settings and maximum sound level.

Like I said, a samsung 32inch LCD is rated 230 watts on the sticker. The set really ( tested with amp meter) has a amp reading of 1.8amps or more.(200w+) when it is on. It does not fluctuate. Even if you have no signal, it drains 200Watts. Backlight and power consumption on those old samsung lcd tv are constantly at max. That isn't true for most energy star tv's but on average, at normal daylight backlight, LCD TV of equivalent size when 32 inch and higher, have greater power consumption than an equivalent size crt (and even worse still if you have projection, which is the most efficient of all 48"=less than 170W LCD 46-inch=270W or more and plasma sets....)
Just to say that crt tv sets suffer from wrong indication of wattage. The sites I mentioned above rate the average CRT monitor at 150W. Yah maybe it really takes 150w at startup (degausser) but running is usually less than 80watts
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post #5 of 12 Old 05-30-2011, 08:50 PM
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Glad you brought this topic up because it's not something that is often discussed at least not with real data. I think the high voltages at the flyback transformer are part of what makes CRTs efficient. I don't claim to know a whole lot about it but as I understand it high voltage and lower current devices are more energy efficient. Perhaps as a technician you could explain that more in depth.
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post #6 of 12 Old 05-30-2011, 10:25 PM
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OK now you have to take an average, not a few once-off static measurement, coz depending how much white is being delivered to the screen, vs mostly black scenes. To this end you have to use something like a kill-a-watt and leave it in for a few days to get a true average.

Beyond that, vendors don't have to use electricity as a pressure point to sell you a flat screen TV. We just transitioned to digital TV (1) then with that HDTV (2) those are the 2 main pressures, else am just the lone weirdo and everybody else use electricity usage as their #1 reason for switching?

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post #7 of 12 Old 05-31-2011, 06:12 AM - Thread Starter
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^ This was more about crt monitors vs lcd.
Also, the test was done with complete black and complete white at max settings.
This was to show how much companies/organisations overrate CRT to sell more LCD. Of course, seeing how little HDTV CRT's there are, most people change to LCD because of 1: Trend 2: Slightly less place taken on desk (not really a lot, do you put things behind your monitor?)
HDTV or not does not apply to CRT monitors since they have a much better quality than most LCD in any size, especially in lower resolutions and color reproduction/contrast)
Also, I was just pointing out that most companies/organisations that say that to save energy when building a computer you take a LCD monitor and show a comparison of like 150W average CRT to like 30W LCD. This is totally not realistic. These companies don't even test wattage, they just check the back sticker that give the max rating. True, a CRT monitor at startup can consume more than 150W, but only for a second or less. The degaussing coil is a necessary part of any crt. That doesn't mean that the monitor consumes 150W.
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post #8 of 12 Old 05-31-2011, 08:20 AM
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Quote:
Originally Posted by neccrttv View Post

This is totally not realistic. These companies don't even test wattage, they just check the back sticker that give the max rating.

Most likely. But not limited to CRT.

My LCD is labeled as 150w, but when I measured it, normal viewing reads 65w.

I realize this is the CRT subforum and u guys luv your CRTs, so be it. Hope u can stay with it and with the features u need in the future.

Look at it another way, CRT with mercury bad for environment, but am gay in the Vatican.

Resistance maybe futile.

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post #9 of 12 Old 05-31-2011, 09:45 AM - Thread Starter
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Quote:
Originally Posted by MrBobb View Post

Look at it another way, CRT with mercury bad for environment, but am gay in the Vatican.

Resistance maybe futile.

I didn't understand that part at all....
LCD (not LED LCD) has so much more mercury considering some have up to 12 mercury lamps.... and most CRT's were leadless from 2000 on. Ever changed mercury lamps on a LCD? I've changed lamps in a lot of LCD monitors and believe me, they will not last as long as rated. Most LCD's will have inverter and lamp problems within the first 10 years. You can't even throw away a LCD monitor without 'disposing of it accordingly to law'.

At least LED TV's have no mercury. That's a first in ecologically sound TV's. The change from CRT to LCD(lamp) was the same as the freaking change from Incandescent bulbs to (mercury) fluorescent bulbs. Save electricity but dispose of them and you're polluting....

^hoffo, the reason CRT can be efficient is because of good regulation more than because of the high voltage. When the TV is not emitting, power consumption is at a minimum but heater, and high voltage (horizontal deflection) is still drawing current. When the raster is white, that is when the TV draws the most current. A good regulation in the power supply means lower consumption. The same thing applies to plasma TV's. They draw much more current when raster is white than in dark scenes. LCD, on the other hand (Lamp), can not dim the backlight during dark scenes unless you lower the setting in the menu. But then, backlight is lowered in all scenes. Higher-end led lcd's can cut partial illumination for the panel and draw much less current but the lower end led can only cut a array (black bars, etc.) and not the whole panel independantly of other leds.
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post #10 of 12 Old 05-31-2011, 11:21 AM
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Being conscience/aware of power consumption is a wonderful thing for the environment.
Rather than debating about CRT vs. LCD vs. plamsa etc.... why not look at those that have half a dozen "wall warts" plugged in 24x7 so they can recharge their phones conveniently so they can talk and/or text while driving their SUV's.
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post #11 of 12 Old 05-31-2011, 06:16 PM
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Quote:
Originally Posted by hoffo View Post

Also I remember reading on Wikipedia on the CRT page that CRTs had the lowest power consumption per screen inch but it must have been edited/erased as it no longer says that. Not sure if completely true or not but seems entirely plausible to me.

I remember reading that too. I believe that is true for larger screen sizes, assuming AVERAGE power consumption (not maximum power consumption, which is what is often cited in specs). Yes, bigger LCDs are power hogs with all the light they have to output. (And think about how much of that light gets wasted!) The average power consumption of a CRT is significantly lower than the maximum power consumption: you're not going to be running a completely white screen the whole time it's on, and also consider the inrush current. On the other hand, the LCD uses pretty much the same amount of power regardless of what it's doing.
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post #12 of 12 Old 06-03-2011, 06:59 AM
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Quote:
Originally Posted by neccrttv View Post

^ This was more about crt monitors vs lcd.
Also, the test was done with complete black and complete white at max settings.
This was to show how much companies/organisations overrate CRT to sell more LCD. Of course, seeing how little HDTV CRT's there are, most people change to LCD because of 1: Trend 2: Slightly less place taken on desk (not really a lot, do you put things behind your monitor?)
HDTV or not does not apply to CRT monitors since they have a much better quality than most LCD in any size, especially in lower resolutions and color reproduction/contrast)
Also, I was just pointing out that most companies/organisations that say that to save energy when building a computer you take a LCD monitor and show a comparison of like 150W average CRT to like 30W LCD. This is totally not realistic. These companies don't even test wattage, they just check the back sticker that give the max rating. True, a CRT monitor at startup can consume more than 150W, but only for a second or less. The degaussing coil is a necessary part of any crt. That doesn't mean that the monitor consumes 150W.

Er, nobody does this to push LCD's over CRT's. That's because nobody sells crt's anymore. Besides people would have to reinforce their desks if they decided to go with 24" ws crt's instead of lcd's.

Don't get me wrong, I still use a 22" Hitachi crt for my Win XP gaming rig and love it at 1600x1200. But large screen lcd's are a lot more practical than large screen crt's. I use a 26" Vizio 1080p LED LCD HDTV for my Win 7 rig and love that too and it doesn't eat up my desktop space.
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