Solved how much a/c power does a laptop need to run

Hewlett-packard / Presario cq62 notebook pc
November 12, 2013 at 11:58:50
Specs: Windows 7, 4.0 GB Ram/AMD 2.2GHz
I was wondering if anyone would be able to tell me how much a/c power a compaq presario CQ62z-200 would need to run. NOT how much watts the battery can power. NOR if it would be better to buy a new battery every year or run it on a/c(well, maybe that is sort of what I'm looking for, 'cuz if it would cost LESS to run it on a/c than, say, $50.00 a year, then that is what I'm trying to find out).

I do understand that there's different factors that come into play, when running a laptop, but if anyone out there has SOME kind of idea, I would greatly appreciate it.

Thank you.

P.S. Someone did a study with a VISTA, that cost about 5cents to run for 8 hours.


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✔ Best Answer
November 13, 2013 at 14:31:07
" are you trying to tell me that it would be more economical to run it on a/c power, rather than the battery?"
Yes, if you never have any intention of using the battery. The battery can only take extra for charging and as been said by others there is a charging efficiency.

However, if you want to use the battery from time to time then you have to weigh in the cost of battery replacement because shelved batteries quickly die of old age rather than use.

In a netshell my take on this is that it is best to keep the battery in place but use the computer plugged in so that it normally runs from the domestic power. The battery will then be preserved better than shelving it and the current drain will be small (because the battery remains in good condition for longer). You also have a facility to use the computer in portable situations when needed. Obviously it will then use power to recharge the battery afterwards but the alternative is to never go portable.

"I was thinking about leaving the battery out, say, every other day"
If this saves anything at all it would be pityfully small, so why put yourself to all that trouble? The battery would have to be recharged sometime anyway so whether it is kept in place or removed every other day would make precious little difference. The big difference is whether you use your computer or not. Like I said, look around at your other domestic usage and there will probably be much greater savings to be made.

Always pop back and let us know the outcome - thanks

message edited by Derek



#1
November 12, 2013 at 12:25:39
Too many variables to consider. How long is the laptop on per day, how powerful is the laptop, what type of programs are you running, etc?

I'm not sure where your going with purchasing a new battery every year, that would have nothing to do with it. And running on battery power isn't going to save you anything considering the laptop is going to draw more power when it's recharging the battery.

Head on up to your local hardware store or Home Depot or whatever and in the electrical section you can purchase devices that will measure current draw. You can also have it measure over a given amount of time and calculate what your cost to run the device is going to be.

message edited by THX 1138


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#2
November 12, 2013 at 13:04:13
Hi, there, THX 1138, thank you for your reply.

My PC is running Win7 Professional, has a 2.2GHz processor, 4GBRam, & 297GB hard drive space. I use my PC most of the day, which can be like up to 16hrs. I do have it set to go to sleep when I need to go do something. I'm not sure what types of programs you're talking about. But, perhaps you can telll me something from this info??? I dunno.

But, thank you for your input. It is greatly appreciated.


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#3
November 12, 2013 at 14:05:11
Laptops by design will only use as much poser as necessary to complete the task you are trying to do. This is done to extend battery life. Some laptops have an AC mode where the laptop runs the processor at full speed all the time. That can cause overheating.

What 2.2GHz processor do you have?

As THX pointed out, you need to charge the battery using AC current. So you are not going to save any money. Actually will cost you money because the conversion from AC to DC and the heat generated equate to lost AC power.

Laptop AC adapters range from 50W to 90W. 50W for 20 hours would equal 1 kilowatt hour. Lets say the average price is 8 cents per KWH. That means you would spend 7 cents a day, if your laptop were pulling 50W all the time. In actuality I would guess the number would be half that or less.

My HP charger is rated at 65W input. So you could go for about 15 hours on a Kilowatt hour. I am guessing it costs about a nickel a day to run. Less than $20 a year.


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Related Solutions

#4
November 12, 2013 at 15:14:35
Hi, there, OtheHill, how are you? Thank you for your reply.

Well, I have an AMD V120 processor.

Wow, I just read your last 2 paragraphs, and if that's true, I would DEFO use my battery less, and a/c power more! Anyways, right now, my battery has only about 46% capacity(according to HP Support Assistant), and so it's not so good as far as the charge lasting. So, when I am able to get a new battery, if leaving the battery out & running on a/c is more economical, hey, I'd go for that!

Again, thank you so much. Much mahalos, take care & God Bless!!!


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#5
November 12, 2013 at 15:29:18
"I'm not sure what types of programs you're talking about. But, perhaps you can tell me something from this info???"

Programs that use a lot of processing power are going to make the CPU run harder and draw more current. Programs like Word or Internet Explorer won't use that much resources so your system will draw less power. Photo editing, video editing and high end games will definitely take more resources and use more power

Leaving the battery out is not more economical as once the battery is charged, it won't draw extra power to charge it. And what would be the point of getting a new battery if you aren't going to use it?

As OtheHill pointed out, power supplies can be rated at different wattages but that doesn't mean they are going to be running at the rated output. A 90 watt power supply may run much less unless you are doing some heavy processing and/or charging the battery. Also, your laptop is never going to draw as much power as the charger is rated for, they always leave some headroom.

If you want a real value as to what your laptop is drawing, go get the current draw meter I was telling you about.

message edited by THX 1138


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#6
November 12, 2013 at 15:31:15
Leaving the battery out will cause it to lose the charge. Why did you buy a laptop anyway if you only use it stationary?

The difference will be negligible with or without the battery. The issue is how to best preserve the battery. There are many schools of thought on that. I suggest you Google it and make up you own mind.


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#7
November 12, 2013 at 17:21:19
Thank you again, THX 1138 & OtheHIll for your input. Seems like I opened up hot topic! LMAO

Anyways, I need to try to decide how to go. I think, THX, the programs that I use that take up the most CPU power are the video games I play(offline), and when I listen to music on YouTube. In general, mostly going online & playing games.

But, thanks again, guys, for your help!!!


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#8
November 13, 2013 at 11:50:49
Domestic power is always the best option (see that already given). The amount used to keep a battery topped up is minimal because the laptop basically runs from the domestic power. The battery will fail much more quickly if left uncharged.

If you are trying to save money I would hazard a guess that your use of other domestic devices would be more to the point, including unnecessary lights and balancing your heating.

Always pop back and let us know the outcome - thanks


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#9
November 13, 2013 at 14:07:00
Hi, Derek, thank you for your response. But, excuse me if I understand you correctly, are you trying to tell me that it would be more economical to run it on a/c power, rather than the battery?

Anyways, I was thinking about leaving the battery out, say, every other day, and using a/c power. That way, I can preserve battery life, while still having the convenience of a laptop.

Ah, well, I shall have to decide what to do. If OtheHill's figures are correct, that may be something for me to consider.

Thanks again!! Take care & God Bless!!!


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#10
November 13, 2013 at 14:31:07
✔ Best Answer
" are you trying to tell me that it would be more economical to run it on a/c power, rather than the battery?"
Yes, if you never have any intention of using the battery. The battery can only take extra for charging and as been said by others there is a charging efficiency.

However, if you want to use the battery from time to time then you have to weigh in the cost of battery replacement because shelved batteries quickly die of old age rather than use.

In a netshell my take on this is that it is best to keep the battery in place but use the computer plugged in so that it normally runs from the domestic power. The battery will then be preserved better than shelving it and the current drain will be small (because the battery remains in good condition for longer). You also have a facility to use the computer in portable situations when needed. Obviously it will then use power to recharge the battery afterwards but the alternative is to never go portable.

"I was thinking about leaving the battery out, say, every other day"
If this saves anything at all it would be pityfully small, so why put yourself to all that trouble? The battery would have to be recharged sometime anyway so whether it is kept in place or removed every other day would make precious little difference. The big difference is whether you use your computer or not. Like I said, look around at your other domestic usage and there will probably be much greater savings to be made.

Always pop back and let us know the outcome - thanks

message edited by Derek


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#11
November 13, 2013 at 15:39:25
Just a quick addition:
Laptop power consumptions vary but you are probably only talking about something like 65W. Tricks with the battery and charging are unlikely to change that by more than a watt or two (if that). Look around the house at the wattages of other things you are using, although I realise that not all of them are in continous use.

Always pop back and let us know the outcome - thanks

message edited by Derek


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#12
November 13, 2013 at 15:44:10
Thank you very much for your input, Derek. What you've told me makes a lot of sense.
And, that is why the battery on my son's laptop has lasted, like, around 4 yrs. He has never liked to keep it unplugged, unless he was going somewhere.
And, I was surprised when, about a month or two ago, he said that it still had charge left. I thought it would be dead after all this time!

OK, sounds like I will be saving on the cost of buying a battery, like, every year, if I keep it plugged into the a/c power. Cool! Sounds good to me!!!

Again, thanks so much! Take care & God Bless!!!


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