Dell Latitude D530 PP17L Quick Reference Manual page 23

The battery operating time is largely determined by the number of times it is
charged. After hundreds of charge and discharge cycles, batteries lose some
charge capacity—or battery health. That is, a battery can show a status of
"charged" but maintain a reduced charge capacity (health).
Check the Battery Charge
To check the battery charge, press and release the status button on the battery
charge gauge to illuminate the charge-level lights. Each light represents
approximately 20 percent of the total battery charge. For example, if the
battery has 80 percent of its charge remaining, four of the lights are on. If no
lights appear, the battery has no charge.
Check the Battery Health
NOTE:
You can check battery health in one of two ways: by using the charge gauge
on the battery as described below and by using the Battery Meter in Dell QuickSet.
For information about QuickSet, right-click the icon in the taskbar, and click Help.
To check the battery health using the charge gauge, press and hold the status
button on the battery charge gauge for at least 3 seconds. If no lights appear,
the battery is in good condition, and more than 80 percent of its original
charge capacity remains. Each light represents incremental degradation. If
five lights appear, less than 60 percent of the charge capacity remains, and you
should consider replacing the battery. See "Using a Battery" on page 21 for
more information about the battery operating time.
Low-Battery Warning
NOTICE:
To avoid losing or corrupting data, save your work immediately after a
low-battery warning. Then connect the computer to an electrical outlet, or install a
second battery in the media bay. If the battery runs completely out of power,
hibernate mode begins automatically.
A pop-up window warns you when the battery charge is approximately
90 percent depleted. If two batteries are installed, the low-battery warning
means that the combined charge of both batteries is approximately
90 percent depleted. The computer enters hibernate mode when the battery
charge is at a critically low level.
Quick Reference Guide
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