Battery drains overnight

DIVIDES

MEMBER
2013 VOLKSWAGEN PASSAT
4 CYL
2WD
AUTOMATIC
129,000 MILES

For the last couple of days I had to jump the battery and it works fine all day. Only overnight it drains. Just parked it in the garage and turned it off, notice something is still on and making a sound underneath the car, passenger side, by rear tire. What could be there that would stay on? Waited 15 minutes and didn't turn off. Went and turned ignition on and it stopped, turned ignition off and it's not there anymore.

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1 Reply

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi,

That is a good question. Try following the directions I listed and see if you can locate a circuit that stops the sound.

1) Make sure the battery is fully charged.
2) Using a voltmeter or multimeter, confirm the battery voltage is 12v or more.
3) Make sure all electrical components are off, the ignition key is removed, all doors are closed, and anything that could cause an electrical draw.
4) Disconnect the negative battery terminal.
5) Set your meter to DC amp. Start at a higher setting, for example, the 10 amp setting on the meter.
6) With the negative battery terminal disconnected, place the red lead of the meter to the battery cable and the black lead to the negative battery post on the battery.
7) With a setting of 10 amps, you should not get a reading. So, work backward to see when you start getting a reading. The reading should require you to select the milliamp setting.
8) If your reading is above the milliamp setting, you have a significant electrical draw. With the voltmeter still connected, remove one fuse at a time in the under-hood fuse box until you remove one that causes a significant voltage drop on the voltmeter.
9) If none of the fuses in the engine compartment fuse box reduces the draw, then you will need to move to the interior fuse panel and repeat the process. However, it is important to follow step 9 before starting.
10) Disconnect the voltmeter before opening the door otherwise, damage to the voltmeter can occur.
11) With the battery still disconnected, locate the door switch button and place it in the closed position and secure it so the vehicle thinks the door is closed.
12) If there is more than one interior fuse box, you may need to check both.
13) Once you locate the fuse which causes a significant drop in the draw, you have identified the circuit involved. At this point, use the fuse legend in the fuse box to confirm what the specific fuse powers, and then, using the correct wiring schematic, work through the circuit to locate the problem.

Let me know if that helps.

Joe