Car Battery Goes Dead After a Few Days

This is my 2012 Hyundai Sonata. I did not drive it for ten days. When I returned home, the battery was dead. I have never had that experience on any car ever I drove.

This Instructable applies to my car, but with all of the modern electronics running in the background on today's automobiles, your car may have this problem, too. This Instructable tells about the solution to my problem, but may be helpful with a similar problem on your car, too. 

Materials needed for this Instructable--none

Tools:

• Multi-meter with an ammeter scale capable of reading up to about three amps.
• 8 mm socket wrench and ratchet
• Spring clamp for connecting a small alligator clip to the battery post

I disconnected the negative (-) battery cable and connected my multi-meter between the cable and the battery post. (Check to be certain it is safe to do this on your car. I was reading the manual for another new vehicle and it seems some things need to be reset if the battery is ever disconnected.) The meter was set to measure DC amperes. Check the terminals on your meter to be certain you have the leads connected properly for the scale on the dial. The leads plug into the meter at different terminals for a current reading than they do for a voltage or a resistance reading.

With everything "off," the doors closed for a few minutes so all dome lights have gone "off," and the key removed; there is a current draw of 470 milliamps, or nearly half of an amp. At a recent visit to the nearest dealership for routine warranty service I asked about this. I was told that is normal. If I am concerned, I should connect a trickle charger when I will leave the car unattended for more than a week.  See the second photo. This is a battery conditioner we bought a few years ago for another purpose. I could mount it in the engine compartment and connect an extension cord to it when we will be gone for more than a week.

My question of the dealership was, "What do I do if I need to leave the car in an airport parking garage for a couple of weeks?" There are no electrical outlets in the parking stalls at any airport garage I know. 

The dealership might have told me there is information in my owner's manual that advises me to pull a special fixture on the fuses, and that would reduce the current draw to a very low level. Yes, I should have read the entire manual after I bought the car, but it is hundreds of pages long. 

The graphic is a page from my owner's manual in the section on fuses. It describes a memory fuse that can be pulled when leaving the car unattended for long periods of time in order to avoid a dead battery. Even if I had read this, I am not sure I would have remembered it or that I would have made the connection in my mind. From doing searches on the Internet, particularly on an owner's forum, I suspect this information has escaped others, too. But, the search for a solution to my problem can be more complex and confusing than it would seem. Some have had the dead battery problem because of a bad cell in the battery, faulty battery cables, a bad diode in the alternator, or even a problem in the car's radio. A dead battery after a few days has been a problem on several makes of car, not just my 2012 Hyundai Sonata.

UPDATE: October 9, 2012-- A friend who owns a 2013 Sonata spoke with his dealer in a different state and city. He did not let the dealer know he is aware of the memory fuse. He asked about the battery going down in a short time. The dealer said new cars of all makes and models have so many electronics items running in the background, even when everything is "off," that the battery on newer cars will go down fairly quickly. When my friend asked what to do, the dealer advised buying a trickle charger. Then my friend asked what he should do if he needs to leave his car at an airport lot for a few weeks. He got only a blank stare from the dealer and no answer. Then my friend led the dealer a bit and asked if there would be any kind of fuse that could be pulled to reduce the current draw. The dealer said he did not know of any!

The photo shows how to remove the panel covering the memory fuse that needs to be deactivated when the car will be unattended for a longer period of time. Just lift the panel to remove it. It is on the left side of the dashboard between the steering column and the door.

Two fuses are ganged together in a yellow plastic holder. You cannot see it while sitting in the driver's seat, but must kneel beside the car with the door open. However, you can locate the fuse holder from the driver's seat by touch without seeing it. Grasp the yellow fuse holder with a thumb and finger. Pull toward yourself. There will be a little click and the dome light will go "off." To restore, just press on the yellow fuse holder with your thumb and replace the fuse cover.

There are two fuses in this holder. To remove the holder from the car, squeeze it under the extensions you grasped on each side and pull. This releases two small catches. Each fuse can be removed separately from the yellow holder and replaced as necessary.

Here you see the reading on my meter after pulling the memory fuse holder. It is only 40 milliamps. That is not enough to make my battery go dead, even if left unattended for weeks. 

Check the owner's manual on your car to see if it has a fuse like the one on my Hyundai Sonata, especially if you have had a dead battery problem after only a few days.