2007 Chevrolet Impala Owner's Manual - Page 164

The battery can be discharged at idle if the electrical loads are very high. This is true for all vehicles. This is because the generator (alternator) may not be spinning fast enough at idle to produce all the power that is needed for very high electrical loads. A high electrical load occurs when several of the following loads are on: headlamps, high beams, fog lamps, rear window defogger, climate control fan at high speed, heated seats, engine cooling fans, trailer loads, and loads plugged into accessory power outlets. EPM works to prevent excessive discharge of the battery. It does this by balancing the generator's output and the vehicle's electrical needs. It can increase engine idle speed to generate more power, whenever needed. It can temporarily reduce the power demands of some accessories. Normally, these actions occur in steps or levels, without being noticeable. In rare cases at the highest levels of corrective action, this action may be noticeable to the driver. If so, a Driver Information Center (DIC) message might be displayed, such as Battery Saver Active or Service Battery Charging System. 164 If this message is displayed, it is recommended that the driver reduce the electrical loads as much as possible. See DIC Warnings and Messages on page 197. Battery Run-Down Protection This vehicle has a feature to help prevent the battery from being drained, if the interior courtesy lamps, reading/map lamps, visor vanity lamps or trunk lamp are accidentally left on. If any of these lamps are left on, they will automatically turn off after 10 minutes, if the ignition is off. The lamps will not come back on again until you do the following: • Turn the ignition on, or • turn the exterior lamps control off, then on again. The headlamps will timeout after 10 minutes, if they are manually turned on before the ignition is off.