Killing my Battery

[JoshMcMadMac]

I went on vacation for a week, and when I got back my battery was almost dead. So, I charged it up enough to get it started and drove it around. I parked it, turned it off, and then started it back up to make sure it would start. It did. I parked it for the night, and the battery was not strong enough to start the car again in the morning. So, I charged it up again and drove it for a few miles. Parked it at home again, turned it off, but it would not start again. I replaced the negative cable yesterday in hopes of remedying the problem. Obviously that didn't make it any better. I ran the battery to the store and swapped it for a new one under warranty. Dropped it in the car and took some readings with the multimeter. I had 12.50V. I measured the amperage with the car off, and was getting 0.2 micro-amps. This seems too low to me. I left the car off for two hours, and got a measurement of 12.44V. I figured that was reasonable, as I might have opened the door once or twice. So, I tried to start the car. With the key on, everything powered on fine. But when I turned the key to start the car, everything died...immediately. I turned the key, and instantly there was a noise, similar to snapping your fingers, and everything was off. Even the lamp on the door was off. I checked the voltage, and got 0.00 at the battery.



I found this very odd, so I talked to my father about it, as I often do to try and talk myself through a situation. He came and looked over the car. We ran jumper cables from his truck to my battery. The lights in the car came on again. I tried to start the car, and everything dies again, with him as a witness. So we tried putting the postive jumper cable to the starter, and got the car to at least try and turn over. It didn't but it made that retched ticking noise of trying really hard. So we pulled the jumper cables off, looked everything over, and tried to get a voltage reading again. Still 0.00V. And I was not using the multimeter improperly, as I know how I got the 12.5 and 12.44 readings, and did it exactly the same to get the 0.00 reading. He gets in the car, turns the key, and the car roars to life! I drive it to my air conditioning guy 10 miles away, turn it off, and it starts right back up.

The negatvie cable is new, and the ignition switch is about one year old. The positive cable is in good shape. The battery, as stated, is new and the proper battery with 1000amp rating. Over a month ago the AMP light would flicker, but not stay on. It would come on with a flicker, and then come off randomly. However, it hasn't done that for a few weeks now. That was what lead me to believe it may be the negative battery cable. Sorry for the long post, but any and all help will be greatly appreciated!

 

[driller]

Sounds like a starter relay problem. Does the starter relay click when you try to start?

I intially thought of battery terminals, but you have a new ground cable and the other looked good, so I presume you've checked them well. Also check the cable terminals at the starter.

But the 0.00 V reading? The only time I've seen that is a dead short. That would be bad. I would be suspicious of bad grounding, even with a new ground cable. Check the ground wire to the body and any other ground connections and make sure the starter relay is grounded well.