Computer Guide

How to prolong laptop battery life

by George Skarbek - 6 November 2007

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How to prolong laptop battery life

Q: Laptop batteries - when used in an office should they be left on charge all the time, or discharged regularly?

A: All laptop batteries have a finite life, typically 3 to 4 years and I will give guidelines to prolong the current lithium-ion batteries.

As the lithium-ion batteries do not have any memory effect, frequent full discharges should be avoided as this shortens the battery life. Leaving the battery constantly on charge is also not a good idea. The best solution to prolong the battery life, although not a really practical one, is to remove the battery and run just from the mains. Unfortunately there is a problem with this method. In the case of a power failure and if you are not running off a UPS (Uninterruptible Power Supply) you will lose your open files and may cause disk corruption, just as with a desktop when the lights go out. If you do decide to store the battery then it should not be fully charged but left at about half capacity for best results. 

Another important factor that is detrimental to long life is heat. The worst combination is to keep the battery fully charged at a high temperature and this is something that happens regularly. It is best not buy spare lithium-ion batteries initially for later use, but if you have a spare then keep it in a cool place at half charge.

Moving My Documents

Q: Can you tell me is it possible to change the location of My Documents to another drive?

A: This is quite easily done by using Windows Explorer. Right-click on My Documents and select Properties and under the Target Folder Location click on the Move button and you will be given a choice of where you wish to have your documents.


Duplicates in Excel

Q: I have an Excel 2003 worksheet with a column containing over 12,000 numbers, entered manually. Every number must be unique, i.e. no duplicates. Does a procedure or function exist for Excel that locates duplicate numbers within a column?

A: I am not aware of an existing function but this is very easy to achieve with one simple IF statement. Start by sorting on the column containing your numbers and for this exercise I assume that they are in column A. In cell B2 enter this formula =IF(A1=A2,"Duplicate","") and copy it down to every cell to B12000. What this IF statement will do is to write Duplicate next to a cell that has an identical number above it and leave a blank if the numbers are not identical. 

Then click on Data, Filter, AutoFilter and in the B column select to show only the cells that contain the word Duplicate.


Registry Cleaners

Q: George, can you recommend a registry cleaner please, preferably a freebie?

A: Do you have a reason as to why you need it? Some free Registry analysing programs give potentially alarming reports hoping you will purchase their product. If your system is stable I suggest that you do not purchase a registry cleaner program.  There is a very small risk that a registry cleaner program may cause problems that currently do not exist.

Microsoft previously had a free registry cleaner program but it was removed from their website some years ago without stating any reasons. It could be that even Microsoft cannot give a 100% guarantee that it works perfectly in all situations. In their knowledge base there is an article referring to a problem caused by one particular registry cleaner that prevented Windows from starting, and also references to erroneous listings generated by other programs.

Having given a lot of reasons why you should not purchase a registry cleaner, I ran one such program on my test computer after it reported several hundred errors. I checked several dozen manually to find they were all referring to either removed or obsolete programs. My registry file was about 70 MB when exported it came to over 12,000 pages of text when opened in Word. After running the program it stated that all problems were fixed. The size of the registry was reduced by a small fraction of 1%. Running benchmarks before and after showed no difference in performance.

In the case of registry cleaners, I would apply the old saying, If it ain’t broke don’t fix it, but I am happy to hear from readers who have other views on this matter.

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