Dell Latitude C840 User Guide - Page 24

Health Gauge The battery life span 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. To check the battery health, 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 "Specifications" for more information about the battery life span. 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 device bay. If the battery runs completely out of power, hibernate mode begins automatically. A low-battery warning occurs when the battery charge is approximately 90 percent depleted. The computer displays a warning message and (if you have enabled audible warnings) beeps, indicating that approximately 10 to 15 minutes of battery operating time remain. If two batteries are installed, the lowbattery 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. For more information on low-battery alarms, see "Power Management." Charging the Battery NOTE: The AC adapter charges a completely discharged battery in 1 to 2.5 hours, depending on whether the computer is on. You can leave the battery in the computer as long as you like. The battery internal circuitry prevents the battery from overcharging. When you connect the computer to an electrical outlet or install a battery while the computer is connected to an electrical outlet, the computer checks the battery charge and temperature. If necessary, the AC adapter then charges the battery and maintains the battery charge. If the battery is hot from being used in your computer or being in a hot environment, the battery may not charge when you connect the computer to an electrical outlet. The battery is too hot to start charging if the light flashes alternately green and orange. Ensure that the computer is disconnected from an electrical outlet and allow the computer and the battery to cool to room temperature. Then reconnect the computer to its electrical outlet and continue charging the battery. For more information on resolving problems with a battery, see "Power Problems." Removing a Battery NOTICE: If you choose to replace the battery with the computer in standby mode, you have only about 1 minute to complete the battery replacement before the computer shuts down and loses any unsaved data. 1. Ensure that the computer is turned off, suspended in a power management mode, or connected to an electrical outlet. 2. If the computer is docked, undock it. 3. Slide and hold the battery bay (or module bay) latch release on the bottom of the computer, and then remove the battery from the bay. Removing the Battery