alternator CADILLAC STS 2009 1.G Owners Manual

Electric Power Management
The vehicle has Electric Power Management (EPM) that
estimates the battery’s temperature and state of charge.
It 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 bring the charge back up. When
the state of charge is high, the voltage is lowered slightly
to prevent overcharging. If the vehicle has a voltmeter
gage or a 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 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. SeeDIC Warnings
and Messages on page 3-79.
Inadvertent Power Battery Saver
This feature is designed to protect the vehicle’s battery
against drainage from the interior lamps, trunk lamp,
glove box lamp, or the garage door opener. When the
ignition is turned off, the power to these features will
automatically turn off after 10 minutes (three minutes
if a new car has 15 miles (24 km) or less). Power will
be restored for an additional 10 minutes if any door
is opened, the trunk is opened or the courtesy lamp
switch is turned on.
3-42