Somethings Killing my battery

I've got a new optima battery and I bought a new alternator and I thought the problem would be solved. I was having a problem with the wire from the +cable to the batt getting real hot and melting but bought a new alternator and that problem was solved, but it still wouldn't hold a charge so I got a new battery because that battery was bad. But now something is still draining my battery. It stayed charged for a day and a half. But now the new battery is drained, what could this be?? Could it be something with the lights because when i turn my lights on my tach doesn't work and soon as i turn the lights off my tach comes back on. It's a 75 impala with a 350.

Pull off a battery cable and put a test light between the cable and the battery terminal.if it lights,you've got a draw. Now start pulling fuses,that should tell you what circuit is drawing power. I'm pretty sure from here you've got your tach miswired. Hope this helps you,Hank

Sounds like a short on the positive side, I'd start looking for a spot on the main battery cable where it's touched up against the exhaust or rubbed through to the frame or body. The + cable likely got hot and melted because there was so much current going through it to meet the demand, even if that demand is a short, it won't know, it's just trying to do it's job. The tach problem may or may not be related, sounds more like a bad ground. As soon as you turn on the lights, the backlight in the tach should light up. If there's a bad ground it's going to seek a path, like the tach circuit board, now that will stop the needle from swinging. Could be I'm way off, but this is where I'd start, start with the current draw first. Sniper

If it melted that big wire, chances are some of the smaller wires got toasted too. You're gonna hafta do some serious circuit chasing!

I'm going to jump in on your thread.......
My son's 89 Dodge 350 car hauler battery gets REALLY HOT and ends up getting fried. The aultenator has been checked out and is OK, the voltage regulator was shot and got replaced and it worked fine for about two months and yesterday he replaced it again after battery died again?????

I had a new optima that had a short internally and it acted the same way.
Do the test recommended by halftanked and if everything checks out take the battery back and have it checked or check it yourself if you have a charger with diagnostics. I've fond that the optimas aren't all that friendly when they loose a charge. You will never get them to recover from just the alternater.

If I understand your post this is happening when the car is parked and ignition off.

A good way to find a draw on the electrical system, you may already know this. But here goes anyway, disconnect the + side of the bat. now connect a voltage meter, red lead to the + cable and the black lead to the + terminal of the bat. ignition OFF. If it reads voltage, start at the fuse box and remove each fuse and notice if you loose the draw. That should id the circuit causing the problem.

If not then, without knowing you car, the next two areas to look at and disconnect the wire one at at time, would be the alt. or the starter area.

To find a short in a wire, disconnect the wire at each end, the wire is now isolated. Set the voltage meter to OHMS connect the red lead to that wire and the black lead the cars ground, it should read open indicating the wire is good and not shorted to groung, if you read continuity ( 0 ohms ) that wire is going to ground and is not a good indication. Why? because the both ends of the wire are not connected/floating going no where and should not read or get to ground.

Is there a way to meke this post perminent. It seems to be an excellent diagnostics thread for just about anyone with electrical problems, as a place to start. Very good info here.:3dSMILE:

do you store change in your ashtray? no joke, had situation with battery draining if parked for a few days (like 3 or 4) replaced the battery, still happened. took it to the mechanic, he saw there was a drain, had me check the cigarette lighter. sure enough there was a penny in there, just enough of a drain to kill it if it sat more than a couple of days.

Red

Okay I used some kind of voltage meter to check this and with the + cable off the batt it stayed at 6.50 because its already drained, and every time i put the + cable on it starts draining lower and lower 6.49, 6.48 and so on. so it is something draining it but can't figure out what it is yet.

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Originally Posted by Dago Red

do you store change in your ashtray? no joke, had
situation with battery draining if parked for a few days (like 3 or 4) replaced the battery, still happened. took it to the mechanic, he saw there was a drain, had me check the cigarette lighter. sure enough there was a penny in there, just enough of a drain to kill it if it sat more than a couple of days.

Red

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Actually my cigarette lighter isn't working

Is it any main fuses or wires that usually cause this problem that I couls start with?? I'm gonna start trying track it down today

yes,you definitely have a draw/short. One quick indicator of this is sparking when you disconnect a battery terminal. I suggested using a testlight instead of a voltmeter because you can see it from almost anywhere in the room while you start diconnecting circuits by pulling fuses one at a time. Yes there are some unfused circuits but don't worry about them now. Go this far and let us know how you make out. Hank