2008 Chevrolet Express Van Owner's Manual - Page 134

When the battery's state of charge is low, the voltage is raised slightly to quickly put the charge back in. When the state of charge is high, the voltage is lowered slightly to prevent overcharging. If the vehicle has a voltmeter gage or voltage display on the Driver Information Center (DIC), you may see the voltage move up or down. This is normal. If there is a problem, an alert will be displayed. 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, rear window defogger, climate control fan at high speed, 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. Accessory Power Outlet(s) Your vehicle may have two accessory power outlets located on the instrument panel. To use the outlet lift the cover. The spring cap cover closes by itself when the outlet is empty. Certain power accessory plugs may not be compatible to the accessory power outlet and could result in blown vehicle or adapter fuses. If you experience a problem, see your dealer/retailer for additional information on the accessory power plugs. Notice: Adding any electrical equipment to your vehicle may damage it or keep other components from working as they should. The repairs would not be covered by your warranty. Do not use equipment exceeding maximum amperage rating of 20 amperes. Check with your dealer/retailer before adding electrical equipment. When adding electrical equipment, be sure to follow the proper installation instructions included with the equipment. Notice: Improper use of the power outlet can cause damage not covered by your warranty. Do not hang any type of accessory or accessory bracket from the plug because the power outlets are designed for accessory power plugs only. Battery Run-Down Protection This feature shuts off the dome lamps if they are left on for more than 10 minutes when the ignition is in LOCK. This will help prevent the battery from running down. 3-18