Set a low-battery warning in Windows

Q I was working on my laptop with Windows Vista when the battery suddenly ran out. There was no warning and I lost quite a lot of work because I had no chance to save it.

I thought the power cable was connected but it must have been pulled out by mistake. Is there any way I can get Vista to warn me when the battery is low?
Edith Hopkins

A We were quite surprised to hear of this problem because both Windows XP and Vista normally warn when a notebook battery gets low. There are two possible causes why this has happened.

It may be that this warning has been disabled for some reason, or it was set to warn too late. The battery capacity reported by Windows does not fall at a steady rate, partly due to the computer needing different amounts of power at different times and because of the way in which batteries work.

Windows actually has two different warnings, for low and critical battery levels, and it can even go into sleep or hibernate modes automatically to prevent work being lost.

To set the warnings in Windows Vista, left-click on the Start button and then on Control Panel. Click on the Mobile PC title and then on Power Options. Click on Change Plans Settings and then on the text Change advanced power settings.

A smaller window will appear. Scroll down to the text Battery and click on the plus symbol next to it to show all the options. Click on the plus next to Low Battery Notification and set to On.

To make the computer hibernate automatically, set the Critical battery action option to Hibernate. It might be surprising when the computer suddenly turns off, but it’s much better than losing work.

Another useful feature of Vista is that if the computer shuts down because of low power, a warning will appear before Vista starts again to make sure the power is connected again.

Windows XP does not have this warning, but it can still warn of low battery and hibernate automatically. Left-click on the Start button and then on Control Panel. Click on the Performance and Maintenance icon, and then on Power Options.

If you are using Classic view, then the Power Options will be the first option on offer. Click on the Alarms tab. Click in both boxes to activate the alarms. Move the slider in the Low battery alarm to 15 per cent and click on the Alarm action button.

Click in the option Display message but leave all the other options deselected. We don’t want the computer to do anything other than warn about the low battery level. Click on OK.

Move the slider in the Critical section to seven per cent. We think that this gives a better chance of hibernate finishing before the battery completely runs out and probably won’t make more than a few minutes difference to the amount of time the computer can be used for.

Click on the Alarm Action button. Deselect the Display message option. If the computer is waiting for you to acknowledge the message before hibernating it may still run out of battery if you happen to be away from the computer for a few minutes.

Click in the box labelled When the alarm goes off, the computer will: and select Hibernate from the list below. Click on OK in both windows to save the changes.