# Some questions about electricity and my bill... **URL:** \ **Category:** Factual Questions\ **Created:** [June 15, 2011, 12:11pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549 "2011-06-15T12:11:01Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [June 15, 2011, 6:08pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/21 "2011-06-15T18:08:28Z")
> [@Machine\_Elf](#): > > On the news this morning they were villifying DVR’s for their “high” power consumption. I have a TiVo, but have not yet checked it with the Kill-A-Watt meter. However, according to [this,](http://www.tivocommunity.com/tivo-vb/showthread.php?t=381090) it consumes 35-40 watts around the clock, costing $2.52-$2.88 per month. I can confirm that my DVR cable box used over 25 watts when it is turned "off’. When I checked this on the AvsForum, some people confirmed it. They said there are more efficient chips available, but the cable companies have little incentive to deploy them. I was pleased to discover that my EEE **nettop** only pulls a few watts on standby, so I rarely shut it off and coming out of standby only takes a few seconds. If you need to leave a computer on all the time, I found that a **netbook** only pulled a few watts when the screen powered off. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 15, 2011, 6:26pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/22 "2011-06-15T18:26:38Z")
> [@gazpacho](#): > > The TV uses more power if the image is brighter. In a lot of TVs they turn up and down the back light LEDs depending on the image being displayed. That’s a relatively recent innovation for LCD displays that use LED backlighting - but it’s an inherent property of plasma displays, in which each pixel produces only the light needed to achieve its designated brightness levels. We have a 65" plasma TV. I haven’t yet tested the power consumption, but I’m very curious to see how much it varies between a pure-black image and a pure-white image. > [@JoelUpchurch](#): > > I can confirm that my DVR cable box used over 25 watts when it is turned "off’. When I checked this on the AvsForum, some people confirmed it. They said there are more efficient chips available, but the cable companies have little incentive to deploy them. Not clear what you mean by “turned off.” If it’s a DVR, then I would guess the hard drive inside is still spinning and buffering program content, even if you’re not watching it, which means the rest of the supporting electronics are active as well. That’s the case with TiVo, which doesn’t really have an “off” mode. Late-model SATA hard drives are down to about 6 watts, which in your case leaves only 19 watts to run the rest of the system. The cooling fan probably eats up a watt or two, plus you’re probably losing another couple of watts in the inefficiency of the power supply transformer/rectifier. That leaves just 15 watts or so to run the rest of the supporting electronics in there, which doesn’t seem all that bad. ---
**Author:** ![KlondikeGeoff](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@KlondikeGeoff](https://boards.straightdope.com/u/KlondikeGeoff)\ **Post date:** [June 15, 2011, 6:48pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/23 "2011-06-15T18:48:36Z")
> [@Stoid](#): > > I am a complete ignoramous about electricity. Don’t feel bad. There is a story about a lady who never removed the burnt out bulbs from the socket, for fear that the electricity would leak out. ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [June 15, 2011, 7:22pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/24 "2011-06-15T19:22:37Z")
Definitely go after the big energy-hungry appliances first. I recently replaced the heating elements and thermostats on our electric water heater, combined with a flush-out, and last month’s electric bill was $50 lower than I expected. If I put a timer on it, I’d save even more by having the heater only turn on when people are home and using hot water; really, what’s the point of the heater running between midnight and 4 AM? Another simple thing: vacuum dust and crud off your refrigerator coils. For most fridges these days, the coils seem to be under the grille on the bottom. Removing the dust lets the fridge operate more efficiently. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [June 15, 2011, 7:23pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/25 "2011-06-15T19:23:39Z")
> [@Machine\_Elf](#): > > Not clear what you mean by “turned off.” If it’s a DVR, then I would guess the hard drive inside is still spinning and buffering program content, even if you’re not watching it, which means the rest of the supporting electronics are active as well. That’s the case with TiVo, which doesn’t really have an “off” mode. Late-model SATA hard drives are down to about 6 watts, which in your case leaves only 19 watts to run the rest of the system. The cooling fan probably eats up a watt or two, plus you’re probably losing another couple of watts in the inefficiency of the power supply transformer/rectifier. That leaves just 15 watts or so to run the rest of the supporting electronics in there, which doesn’t seem all that bad. “off” is a huge minefield of misunderstanding with modern electronics. Like my Wii example there is off but still have wifi and bluetooth running. Off with the button glowing red instead of orange and unplugged off. As someone who works in the cell phone industry 15 watts is an enormous amount of power. I can watch youtube videos over the cell network using only a couple of watts. That is a lot more processing power than is needed to demodulate and re-encode the the picture. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [June 15, 2011, 7:28pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/26 "2011-06-15T19:28:20Z")
> [@Machine\_Elf](#): > > However, the speakers are on 24/7, and they consume 23 watts whether they’re making noise or not. That was a big surprise for me. That’s probably because they are of the “powered” variety. Passive speakers (voice coil+speaker cone) consume no power beyond that of the amplifier that drives them. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 15, 2011, 7:41pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/27 "2011-06-15T19:41:53Z")
> [@Musicat](#): > > That’s probably because they are of the “powered” variety. Passive speakers (voice coil+speaker cone) consume no power beyond that of the amplifier that drives them. Correct on both counts. I was just surprised that they dissipate that much power without even making noise. ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [June 15, 2011, 8:10pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/28 "2011-06-15T20:10:15Z")
> [@Machine\_Elf](#): > > Not clear what you mean by “turned off.” If it’s a DVR, then I would guess the hard drive inside is still spinning and buffering program content, even if you’re not watching it, which means the rest of the supporting electronics are active as well. That’s the case with TiVo, which doesn’t really have an “off” mode. Late-model SATA hard drives are down to about 6 watts, which in your case leaves only 19 watts to run the rest of the system. The cooling fan probably eats up a watt or two, plus you’re probably losing another couple of watts in the inefficiency of the power supply transformer/rectifier. That leaves just 15 watts or so to run the rest of the supporting electronics in there, which doesn’t seem all that bad. I mean off as in I press the off button. In that mode, it should only use enough power to monitor the infrared port and the keyboard and a timing circuit to wake up when it is time to record a show. It could be implemented as a function inside the main processor or as a separate micro-controller that would only draw milliwatts. Here is a link to the Avsforum discussion: [http://www.avsforum.com/avs-vb/archive/index.php/t-1198126.html](http://www.avsforum.com/avs-vb/archive/index.php/t-1198126.html) I’d forgotten that the [energystar.gov](http://energystar.gov) site said that it would save 2 billion a year if all set top boxes are energystar compliant. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 15, 2011, 8:25pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/29 "2011-06-15T20:25:22Z")
> [@JoelUpchurch](#): > > I mean off as in I press the off button. In that mode, it should only use enough power to monitor the infrared port and the keyboard and a timing circuit to wake up when it is time to record a show. It could be implemented as a function inside the main processor or as a separate micro-controller that would only draw milliwatts. After looking at the [Bright House DVR website,](http://brighthouse.com/corporate/shop/tv/dvr) they talk about being able to pause/rewind live TV, implying that the DVR is buffering program content through the hard disk. Is it possible this system is still active even after you’ve pressed the “off” button? Can you hear whether or not the disk spins up/spins down when you hit that off button? ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [June 15, 2011, 9:23pm UTC](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549/30 "2011-06-15T21:23:47Z")
> [@Machine\_Elf](#): > > After looking at the [Bright House DVR website,](http://brighthouse.com/corporate/shop/tv/dvr) they talk about being able to pause/rewind live TV, implying that the DVR is buffering program content through the hard disk. Is it possible this system is still active even after you’ve pressed the “off” button? Can you hear whether or not the disk spins up/spins down when you hit that off button? You will have to ask someone else. I turned off the cable TV when my roommate moved out, since he was paying for it and I didn’t care that much. [Previous page](https://boards.straightdope.com/t/some-questions-about-electricity-and-my-bill/585549.md?page=1)