Posted by sorry_no_email on July 24, 2006, 1:09 pm
How much power does a hard drive use? Looking at the label of my WDC
120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
12VDC-0.45A. This says to me that it draws between 4w and 5.4w DC, but
I wonder how much extra AC juice it draws given the inefficiency
inherent in the power supply. Let's say it draws another 10w AC (120V
here in the USA). At 10 cents per thousand watt-hours, it would cost
about 10 cents every four days in extra electricity.
This is for my TiVo, and I am trying to decide whether to add a drive
or replace the main drive. The box runs 24/7/365, which means another
$10 a year for two vs. one hard drive.
Posted by Mike T. on July 24, 2006, 1:44 pm
> How much power does a hard drive use? Looking at the label of my WDC
> 120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
> 12VDC-0.45A. This says to me that it draws between 4w and 5.4w DC, but
> I wonder how much extra AC juice it draws given the inefficiency
> inherent in the power supply. Let's say it draws another 10w AC (120V
> here in the USA). At 10 cents per thousand watt-hours, it would cost
> about 10 cents every four days in extra electricity.
> This is for my TiVo, and I am trying to decide whether to add a drive
> or replace the main drive. The box runs 24/7/365, which means another
> $10 a year for two vs. one hard drive.
Ok, first your calculations are off a bit. It uses about 4W of the 5V line
(5*.8) and a little more than 5W off the 12V line (12*.45) Add those two
together, and round it off to 10W. Poor power supplies tend to be about 60%
efficient. So about 17W A/C is going to be used, at most.
That's about 10 cents every 2 1/2 days in electricity, or about $14.60/year.
But that's peak currents. Idle will be about 75% of that. Roughly $11 a
year, so I guess your calculations weren't too far off. It'll be a little
more than $11 per year because the drive won't always be idle, but it'll be
a little LESS than $11/year also, as the power supply is probably more than
60% efficient (hopefully).
If electricity use is really so much of a concern, it might be wisest to
replace the whole TIVO box with something that doesn't need to be powered
24/7/365. We use a non-Tivo DVR which maxes out at 46W total A/C power use
when recording and playing back simultaneously from hard drive. It drops to
5W total A/C power use in standby mode, and that's the mode that it is in
most of the time.
I don't know how much power the Tivo box uses, but I've already figured it
uses about 17W A/C power for each hard drive alone. That's just the hard
drive. -Dave
Posted by Jon D on July 24, 2006, 4:04 pm
>
>> How much power does a hard drive use? Looking at the label of my
>> WDC 120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
>> 12VDC-0.45A. This says to me that it draws between 4w and 5.4w
>> DC, but I wonder how much extra AC juice it draws given the
>> inefficiency inherent in the power supply. Let's say it draws
>> another 10w AC (120V here in the USA). At 10 cents per thousand
>> watt-hours, it would cost about 10 cents every four days in extra
>> electricity.
>>
>> This is for my TiVo, and I am trying to decide whether to add a
>> drive or replace the main drive. The box runs 24/7/365, which
>> means another $10 a year for two vs. one hard drive.
>>
>
> Ok, first your calculations are off a bit. It uses about 4W of the
> 5V line (5*.8) and a little more than 5W off the 12V line (12*.45)
> Add those two together, and round it off to 10W. Poor power
> supplies tend to be about 60% efficient. So about 17W A/C is going
> to be used, at most.
>
> That's about 10 cents every 2 1/2 days in electricity, or about
> $14.60/year.
>
> But that's peak currents. Idle will be about 75% of that. Roughly
> $11 a year, so I guess your calculations weren't too far off.
> It'll be a little more than $11 per year because the drive won't
> always be idle, but it'll be a little LESS than $11/year also, as
> the power supply is probably more than 60% efficient (hopefully).
>
> If electricity use is really so much of a concern, it might be
> wisest to replace the whole TIVO box with something that doesn't
> need to be powered 24/7/365. We use a non-Tivo DVR which maxes out
> at 46W total A/C power use when recording and playing back
> simultaneously from hard drive. It drops to 5W total A/C power use
> in standby mode, and that's the mode that it is in most of the
> time.
>
> I don't know how much power the Tivo box uses, but I've already
> figured it uses about 17W A/C power for each hard drive alone.
> That's just the hard drive. -Dave
>
Lots of good info there mate. One thing seems odd and that is the
idle draw at 75% of peak. I thought it was much less than that.
Maybe 25%?
Posted by Rod Speed on July 24, 2006, 4:42 pm
>>
>>> How much power does a hard drive use? Looking at the label of my
>>> WDC 120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
>>> 12VDC-0.45A. This says to me that it draws between 4w and 5.4w
>>> DC, but I wonder how much extra AC juice it draws given the
>>> inefficiency inherent in the power supply. Let's say it draws
>>> another 10w AC (120V here in the USA). At 10 cents per thousand
>>> watt-hours, it would cost about 10 cents every four days in extra
>>> electricity.
>>>
>>> This is for my TiVo, and I am trying to decide whether to add a
>>> drive or replace the main drive. The box runs 24/7/365, which
>>> means another $10 a year for two vs. one hard drive.
>>>
>>
>> Ok, first your calculations are off a bit. It uses about 4W of the
>> 5V line (5*.8) and a little more than 5W off the 12V line (12*.45)
>> Add those two together, and round it off to 10W. Poor power
>> supplies tend to be about 60% efficient. So about 17W A/C is going
>> to be used, at most.
>>
>> That's about 10 cents every 2 1/2 days in electricity, or about
>> $14.60/year.
>>
>> But that's peak currents. Idle will be about 75% of that. Roughly
>> $11 a year, so I guess your calculations weren't too far off.
>> It'll be a little more than $11 per year because the drive won't
>> always be idle, but it'll be a little LESS than $11/year also, as
>> the power supply is probably more than 60% efficient (hopefully).
>>
>> If electricity use is really so much of a concern, it might be
>> wisest to replace the whole TIVO box with something that doesn't
>> need to be powered 24/7/365. We use a non-Tivo DVR which maxes out
>> at 46W total A/C power use when recording and playing back
>> simultaneously from hard drive. It drops to 5W total A/C power use
>> in standby mode, and that's the mode that it is in most of the
>> time.
>>
>> I don't know how much power the Tivo box uses, but I've already
>> figured it uses about 17W A/C power for each hard drive alone.
>> That's just the hard drive. -Dave
>>
> Lots of good info there mate. One thing seems odd and that is the
> idle draw at 75% of peak. I thought it was much less than that.
> Maybe 25%?
Yeah, he mangled that considerably.
http://www.storagereview.com/comparison.html
The two power consumptions are in the pulldown sort list.
Posted by Mike T. on July 25, 2006, 8:09 am
>>
>> Lots of good info there mate. One thing seems odd and that is the
>> idle draw at 75% of peak. I thought it was much less than that.
>> Maybe 25%?
> Yeah, he mangled that considerably.
No, I didn't. I said idle power consumption. Sleep mode is significantly
lower, but I'm not sure that applies to DVR. That is, I've not seen a DVR
that you could put to sleep. -Dave
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> 120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
> 12VDC-0.45A. This says to me that it draws between 4w and 5.4w DC, but
> I wonder how much extra AC juice it draws given the inefficiency
> inherent in the power supply. Let's say it draws another 10w AC (120V
> here in the USA). At 10 cents per thousand watt-hours, it would cost
> about 10 cents every four days in extra electricity.
> This is for my TiVo, and I am trying to decide whether to add a drive
> or replace the main drive. The box runs 24/7/365, which means another
> $10 a year for two vs. one hard drive.