Alarm goes off when I disconnect the battery!

Asked by Apr 06, 2015 at 07:38 AM about the 2000 Volkswagen Passat GLS

Question type: Maintenance & Repair

I went on vacation for 6 weeks and when I returned the battery was drained. I charged it and everything was fine. I am leaving again on a long vacation and thought I would disconnect the battery to avoid the problem on my return, but when I disconnect the battery cable the alarm goes off.

6 Answers

4,945

Put your key in the ignition, turn to accessory, and then connect the battery. Should be okay.

Thanks Scott but I want to disconnect the battery as it drains when I am away for more than 4 weeks. The problem is when I remove the battery cables, the alarm goes off. This seems strange unless the alarm has another power source. A related question if I keep charging the battery every time it drains, does it reduce the life of the battery?

4,945

If you remove the battery positive cable while the key is in the ignition (off) it may defeat the alarm. The alarm may be able to function after the battery is disconnected due to stored energy in it's system, capacitive or battery. BTW, if you have a slow drain you should locate it...or install a trickle-charger to maintain the battery for long duration parkings.

1 people found this helpful.

Thanks Scot. How can I find out if there is a slow drain and how can I locate it? The alarm is certainly using the battery and I also notice that the LCD display of the clock and mileage indicators are on when the ignition is off.

4,945

The LCDs draw only a few milliamps...no worry there. As an electronics tech, I have used a clamp on ammeter to measure the current through the primary positive lead to the fuse box while the vehicle is off. Then, systematically, pulled a fuse for a circuit, checked the reading, replaced the fuse and moved on to the next circuit. It is tedious but effective. You can also obtain a solar charger identical to what the dealers use. It connects to the OBDII port and can be placed on the dash or window to provide a maintenance charge.

2 people found this helpful.
4,945

Automotive batteries are not like lithium ION batteries in portable devices. They have lead plates and electrolytic fluid that react chemically to store and discharge electrons. These lead-acid batteries typically last 5 years or more. The standard (un-sealed) lead-acid batteries can be reconditioned by replacing the electrolytic fluid. It may be you simply have a tired battery...

1 people found this helpful.

Your Answer

Passat

Looking for a Used Passat in your area?

CarGurus has 25,669 nationwide Passat listings starting at $1,000.

ZIP:

Volkswagen Passat Experts

  • #1
    tenspeed
    Reputation
    1,530
  • #2
    Chrisand Edwards
    Reputation
    1,420
  • #2
    Tom Demyan
    Reputation
    1,420
View All

Related Models For Sale

Used Volkswagen Jetta
421 Great Deals out of 25,220 listings starting at $1,299
Used Honda Accord
424 Great Deals out of 101,059 listings starting at $1,200
Used Toyota Camry
761 Great Deals out of 70,900 listings starting at $1,200
Used Nissan Altima
720 Great Deals out of 70,156 listings starting at $1,495
Used Audi A4
215 Great Deals out of 12,607 listings starting at $1,000
Used BMW 3 Series
833 Great Deals out of 32,432 listings starting at $995
Used Honda Civic
333 Great Deals out of 52,978 listings starting at $1,200
Used Chevrolet Malibu
480 Great Deals out of 49,315 listings starting at $2,000
Used Volkswagen GTI
80 Great Deals out of 6,287 listings starting at $2,395
Used Hyundai Sonata
365 Great Deals out of 49,687 listings starting at $1,250
Used Volkswagen Golf
67 Great Deals out of 4,893 listings starting at $999

Used Cars For Sale

2017 Volkswagen Passat For Sale
30 Great Deals out of 2,351 listings starting at $11,999
2016 Volkswagen Passat For Sale
24 Great Deals out of 961 listings starting at $7,950
2015 Volkswagen Passat For Sale
91 Great Deals out of 3,458 listings starting at $7,200
2014 Volkswagen Passat For Sale
74 Great Deals out of 2,558 listings starting at $6,495
2013 Volkswagen Passat For Sale
75 Great Deals out of 2,456 listings starting at $5,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.