alternator GMC ENVOY 2007 Owner's Manual

Electric Power Management
This vehicle has Electric Power
Management (EPM), an advanced control
system. It estimates the battery’s temperature
and state of charge and then adjusts the voltage
for best performance and extended life of
the battery.
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, 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,
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 Battery
Voltage Low. If this message is displayed, it is
recommended that the driver reduce the electrical
loads as much as possible. SeeDIC Warnings
and Messages on page 222.
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