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SuperDave
SuperDave, ASE Certified Technician
Category: Hyundai
Satisfied Customers: 1173
Experience:  over 14 years experience
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Drained..a short circuit somewhere that..alternator..central locking

Resolved Question:

my battery is drained overnight, not due to anything being on in the car, just wondering if this would be a short circuit somewhere that is a know fault, the alternator is fine, putting out 14v, and once the car is running for a bit the battery is fully charged again and everything works fine, its getting to the point where the central locking doesnt even work the battery is that dead.
Submitted: 2 years ago.
Category: Hyundai
Expert:  SuperDave replied 2 years ago.

How did you test the battery?

Customer: replied 2 years ago.
used a different battery of the same size ei: cca, no change, still got drained
Expert:  SuperDave replied 2 years ago.
Ok , Do you own a voltmeter?
Customer: replied 2 years ago.
battery has 0v after one night of not driving, about 14 hrs to drain it dead, dont have one here at the moment though, thats also how i know the alternator is putting 14v out
Expert:  SuperDave replied 2 years ago.
A car battery is used to store electrical power in reserve to be used when the
car engine is started. Several conditions can occur that will cause a battery to
lose its charge overnight. There are several "live" electrical circuits that can
draw electrical power from the battery when the key is in the off position
As
a battery ages it loses its ability to hold a charge, as a rule of thumb a
battery will last about three to four years. If the battery is fairly new you
will need to start the engine by jump starting or charging the battery using a
battery charger. Once the engine is running test the alternator in the charging
system. If the alternator fails, replace it with a new or rebuilt unit and
re-test system, if the alternator tests ok proceed to the next step.
This
first test is simple but you would be surprised at how many people simply leave
their headlights on overnight. If the battery is dead check the headlight
control switch. If the switch is in the on position turn the switch off and jump
start or charge the battery. The battery should re-gain its state of charge
after about 15 minutes of driving and your problem will solved. If headlight
switch is off proceed to next step.
Inspect the interior illumination lights
(dome light) when all the doors are shut the interior lights should go off. If
the lights stay on check the headlight interior light bypass switch located at
the headlight switch. This switch is designed to illuminate the interior lights
indefinitely when the doors are closed and is used when people are left inside
the car and need light for a particular reason. To check the headlight interior
light bypass switch turn the headlight control knob fully right then left, you
should feel a small bump in the operation letting you know when the switch is
activated. Deactivate the switch and re-test dome light operation. Some cars
have a delay sentinel that will leave the interior light illuminated for a
preset amount of time and is used for safety reasons. If this delay mechanism
fails it can leave the interior light on draining the battery. If this is the
case the interior light delay sentinel or Body Control Module will need to be
replaced. If all tests ok proceed to next step.
Inspect the car stereo tape
deck or CD player, sometimes a tape or CD will get stuck in the player either
loading or ejecting causing the motor inside the tape deck to stop. This small
motor can draw enough electrical power to drain the battery overnight. If a tape
or CD is stuck in the player try using a small flat bladed screwdriver or small
tweezers to remove the culprit. If the stuck tape or CD will not come out.
Remove the player and disconnect the unit. Once the unit has been removed either
replace the player or send it to a stereo repair shop and reinstall when
repaired. If player tests ok proceed to next step.

Inspect the glove box
illumination light, in most cases this light is controlled by a small pin
switch. If this switch malfunctions or is misaligned it will allow the glove box
light to stay on draining the battery down overnight. To check for this
condition look for the light inside the glove box through the small cracks in
the glove box door. If this light is illuminated when the glove box door is shut
replace or readjust the switch to operate properly and recheck light operation.
If it tests ok proceed to next step.
Inspect the trunk illumination light,
in most cases this light is controlled by a small pin or a mercury level switch.
To test the trunk light operation observe the light as you close the trunk lid,
the light should go off when the trunk lid is nearly shut. If the light doesn't
go off replace or readjust the switch and recheck operation. If it tests ok
proceed to next step.
Inspect the hood (covers the engine) illumination
light, in most cases this light is controlled by a small pin or a mercury level
switch. To test the hood light operation observe the light as you close the
hood, the light should go off when the hood is nearly shut. If the light doesn't
go off replace or readjust the switch and recheck operation. If it tests ok
proceed to next step.
Inspect the cigarette lighter in both front and rear
passenger compartments, remove the lighter unit and look down inside the light
socket. You are looking for debris that can cause an electrical draw like a
penny or a gum wrapper. Anything that can cause an electrical draw will drain
the battery power. If debris is found remove it with a small pair of tweezers.
(Note: sometimes when inserting tweezers or removing debris from the cigarette
lighter a fuse can blow, if so replace the fuse with new after the debris has
been removed) If the lighter is ok proceed to next step.
Inspect the electric
seat control switch, this switch can become sticky or weak allowing the switch
to stay engaged forcing the seat motor to draw power from the battery until
dead. To check for this condition observe the operation of the seat control
switch if it does not return the neutral position or is sticking in one position
replace the switch with new and recheck.
If no other electrical accessory is
causing the battery to drain overnight a manual draw check of the electrical
system will need to be performed. What this means is you will be checking the
electrical draw the battery has on it when the car is locked up, with the key in
the "off" position". First open the hood and disable the under hood illumination
light, if equipped. Next, with the key off and the doors locked wait 15 minutes,
then disconnect the battery cable on the negative side. (The 15 minute wait
allows the computers to go into "sleep mode" and shuts down all electrical).
Attach a test light between the negative battery cable end and the negative
battery terminal. The test light should illuminate dimly or not at all. If the
test light is on brightly there is a strong electrical draw in the system. To
locate this electrical draw start removing fuses one at a time. When the test
light goes out the circuit in question has been located. You will need a car
repair manual to identify all accessories in a particular circuit, repair as
needed and re-check system
SuperDave, ASE Certified Technician
Category: Hyundai
Satisfied Customers: 1173
Experience: over 14 years experience
SuperDave and 5 other Hyundai Specialists are ready to help you

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