More reader questions answered: power states

Well I survived my travels, and now am safely ensconced back in Tech–for Everyone Headquarters. Today I will answer some reader questions in the hopefully familiar Q’s and their A’s format.

Q: I plugged my media player into a USB overnight, and in the morning the battery was only half charged. This is a new player. What gives?
A: Media players that recharge their batteries via attachment to a USB port are taking advantage of the fact that USB is a powered bus which supplies 5 volts. For a device, such as a media player, to receive the voltage, it must be 1) plugged in, 2) the computer must be plugged in and 3) the computer must be on. Here is where this reader’s problem lies. Windows has four basic power states; working, sleep, soft off, and full off… and subsets of the “sleep” state, such as “hibernation”.
For the reason of power savings, and to reduce power consumption and increase battery life, a PC is put into one of the latter three states either deliberately, or after a certain (adjustable) period of inactivity. These reduced power states shut off power to your monitor, your hard drive, and (you guessed it) your peripherals by powering down the buses they’re attached to.
The reader had attached their media player to a laptop and put the machine into hibernation mode… and not touched it for several hours (inactivity)– a very “deep” power savings. This practically completely shuts down the USB bus. And so, no charging will occur.
But, some charging did occur. Why? Because the whole purpose of choosing a powered-down state, such as “sleep”, instead of completely turning off the machine, is to have a faster “warm up” when you are ready to start working again. This is done by avoiding as much of the boot process as possible: some memory chips retain power to keep the O/S ‘alive’ and aware of current settings, and the operating system maintains an “awareness” of the attached devices. The awareness of which devices are attached is done by maintaining a very low bus voltage (about half a volt). In this reader’s case, enough of a voltage to charge his player somewhat… an indicator that his battery is indeed new, and indicates that it would fully charge quite quickly during a fully powered (active) state.

Q: My laptop goes to sleep too soon. How do I give myself more time?
A: You can adjust the length of the “inactivity” time allowed before your machine goes into a power savings mode quite easily. For those of you really concerned with power savings, you can make it kick in after 5 minutes; and for you power users, you can turn it off completely (It will still be available from the Start >Shut Down menu).
Vista users will find the settings by clicking Start >Control Panel >Hardware and Sound >Power Options (in XP it’s Control Panel >Power Options), as shown below.

Here you can quickly choose from one of three power policies, to fit the current usage you are using. In the picture above, I am plugged into the wall and I want every ounce of performance. When it is time to go mobile and I will be running on my battery, I want to sacrifice some of the bells and whistles and stretch my time between rechargings to the maximum, I will click on middle radio button.

To set my own times, I click on the “Change when the computer sleeps” link in the left column.

Use the drop down arrows to select the length of time your machine is idle before the power is cut to your monitor, and when it general goes into the power-saving sleep mode. I have set a fairly typical policy here, but my advice for the reader who asked the question was leave the setting for the monitor (screen) to a short time, but extend the sleep time to an hour.. or longer.

Today’s free link:a quick way to tell if your machine has picked up some malware is a visit to Panda’s Infected or Not website and get a free scan.

Copyright 2007 © Tech Paul. All rights reserved.

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