Electric Power Management; Battery Run-Down Protection - Chevrolet HHR 2010 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 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.

Battery Run-Down Protection

The vehicle has a battery saver feature designed to
protect the vehicle's battery.
When any interior lamp is left on and the ignition is
turned off, the battery rundown protection system
automatically turns the lamp off after 20 minutes.
This prevents draining of the battery.
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