Mysterious Battery Drain


#1

I have a 1995 Mits Eclipse and my battery drains over the weekend when the car is parked. I have replaced the alternator and checked all the wires that run to the battery. Can some one help me?


#2

Have you done any electrical work other than what you have said lately? New stereo? New speakers, etc? I had an issue with a vehicle of mine that when I placed the dash cover back on after replacing the stereo, I pinched the cable. This caused a discharge of the battery over a few days over and over. Took me a while to figure it out because it didn’t happen until a few days after the stereo was in and working fine!


#3

No i dought it as is. Havent done anything to it. I starting to take the negative wire of the battery at night, but i know that is going to get old.


#4

A battery that is bad will sometimes fail to hold a charge for several days, but might be ok for overnight restart. If you have a substitute you can put in the car you can eleminate this possibility.


#5

When you reattach the negative cable, do you get a pretty healthy spark? If so, you have something in the car that is draining the battery. The first step is to see if some light is staying on when it shouldn’t such as a trunk light, underhood light, glove compartment light, etc.

If this doesn’t fix the problem, then you need to put a test lamp between the battery terminal and the cable end. If it is on, keep pulling fuses until it goes off. This will be the circuit that is causing the drain on the battery.


#6

my understanding is that once you drain a battery all the way down (deep discharge), it kills the battery.


#7

my understanding is that once you drain a battery all the way down (deep discharge), it kills the battery.

It certainly is not good for it, but doing it once usually will not kill it. I will take some life off of it and if it is close to death it can push it over the edge.