What is draining my car battery?

[alynej]

The battery on my Mazda 3 started turning up dead almost every morning beginning during winter. now I bought a new battery in summer and things seemed to be better for a month or two, but now the problem is back, and worse than before.

Any time the car sits for more than about 12 hours without being driven, the battery is likely to be completely dead, to the degree that the power locks won't even work. If I get a boost or put it on a trickle charger, the car drives fine once it starts.

What could be causing it? How expensive a problem is this likely to be?

 

[Tom Thumb]

Put a multimeter on it and start pulling fuses until you find the circuit,( put meter between neg. post and terminal after removing neg terminal from battery.)Once you have no draw on meter you have found bad circuit.

 

[alynej]

Put a multimeter on it and start pulling fuses until you find the circuit,( put meter between neg. post and terminal after removing neg terminal from battery.)Once you have no draw on meter you have found bad circuit.

i have really no idea about this , waiting for mechanic to come and check my car , anyhow thank you so much for letting me know!

 

[MEP001]

It's called a parasitic drain. Since you're unwilling or unable to look into it yourself, you'll have to rely on your mechanic to figure it out. It could be anything, and you'll just have to pay whatever he charges once he figures it out.

 

[Greg_T]

Put a multimeter on it and start pulling fuses until you find the circuit,( put meter between neg. post and terminal after removing neg terminal from battery.)Once you have no draw on meter you have found bad circuit.

Agreed - we run an auto workshop with an auto electrician, and this is similar to what we would do. Would be happy to have a look at it for you, but we're on another continent!

 

[AZcarwashman]

My father was having the same issue with his Chrysler 300. Pulled all fuses and still couldn’t find the issue. In the end, it ended up being a secondary security system that was installed at the factory and only active until the car is sold. This system isn’t used by the end user and is different than the one controlled by your key fob. Had Chrysler remove this system and all was fixed with the battery drainage.