Battery Run-Down Protection - GMC 2007 Yukon Denali Owner's Manual

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,
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. 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 254.

Battery Run-Down Protection

This feature shuts off the dome, and reading
lamps if they are left on for more than 10 minutes
when the ignition is off. This will keep the
battery from running down.
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