Battery keeps going dead

[dotdat]

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The battery in my 810 coupe keeps going dead after it sets for a week or two. The battery is only a year old. Maybe I could swap it out for a good one from another vehicle. This would tell if it's the battery or not.

 

If not the battery, maybe I could pull some fuses to narrow down the culprit. All this while monitoring the amperage being sucked from the battery.

 

Yes, I've already checked the trunk lamp and it goes out when trunk is closed. The clock stays running, but that should not draw that much current.

 

Any ideas anyone?? And how does my proposed trouble shooting method seem to you.

[INDY510]

trying your Datsun battery on a brand new car might be more expensive, but just as good of a trouble shooting method ... :lol:

 

Try dissconnecting the negative battery cable from the battery, when you leave the car parked for weeks . if it holds a charge, then keep doing that

[Z-train]

Connect the + cable in total darkness.If there is a draw,there should be the tiniest spark when you connect the positive cable.If so,disco the fusible links one at a time & repeat.

[DanielC]

"Connect the + cable in total darkness" Do not do that.

 

Disconnect the negative cable. Accidentally touching the wrench to anything metal on the negative cable clamp, and the body does nothing.

 

Accidentally touching the wrench to anything metal on the positive cable clamp, with the negative battery connected, and the body makes a dead short circuit across the battery. Batteries have actually blown up by doing this.

 

OK, now that is out of the way, disconnect the negative battery cable, and put a test light between the negative battery cable, and the negative battery post. If you have a drain the light will light up. Pull the fuses, to see if you can find the circuit with the drain.

[Z-train]

"Connect the + cable in total darkness" Do not do that.

 

 

Ther is no problem with doing what i said.

[ggzilla]

There are two problems with that:

 

(i know you Z-train would never do the following, but I have, and others will do it again...)

 

1. It's total darkness, so a person might accidentally touch the cable to the terminal AND to the battery hold-down frame or something else at the same time, making big spark.

 

2. Taking off the positive cable by itself is problematic for the reason Daniel gave. Always remove NEG cable first, then POS is the standard safety method.

 

You will get the same tiny spark with either cable end. Stereo often cause a tiny spark, and can only last a couple weeks before draining the battery. Anything aftermarket is suspect: alarm, stereo/radio/whatever

 

The test light is also safer than a spark. If the battery was recently charged, hydrogen gas fumes may exist and blow the battery upon spark. One time the top of a battery grazed my temple on it's way over the roof of the house. Sure it is rare, but once was enough. No spark near battery.

[Laecaon]

Im gonna say, every battery I have ever touched at work, and I touch at least one a day, I disconnect the positive terminal, connect a wire, and then tighten the nut back down. I also just use a drill with a socket attached.

 

Changed my alternator without disconnecting the battery. Heck I have done everything in my car without disconnecting the battery.

 

Yes I know its wrong. And because of that I am always mindful of being shocked, or causing a ground.

[mklotz70]

You won't get shocked, but you could create a 300A+ short. I dropped a wrench across the batt terms one time.....turned the wrench red hot in about 3 seconds.

 

The test light DanielC talked about is the best method since you can easily monitor the status of the drain as you're pulling fuses. If you have a cigarette lighter installed....you might check it too....the coils inside can get enough corrosion to make a slight short or the coil bends or brakes and makes a slight contact to another causing the resistance to drop. Typically, a cig lighter is hooked up after the key, but on some cars, they work all the time.

 

I'm assuming Ztrain meant to just check the spark in total darkness....no do the cable disconnect. It will work....I don't like intentionally making sparks around the battery, but it's assumed that it will be a really tiny spark. Neg cable is the better way to go, but a $3 test light from HF or the parts store is by far the best. :)

[banzai510(hainz)]

a week or 2 is abit harder to detect.

 

 

use a test light. pull the neg batt post and put test light in between Neg batt post and the cable end you just removed. If light ON then its draining.

 

about 37-50 secs into this vid is how to hoooke up

 

you could try removing the +output of the alternaotr also if a diaode is bad there but like you said it dies in 2 weeks. Ciouls just be bad cables ,weak battery

[dotdat]

Shazaaam ..... This should be enough to give me a good start to find the culprit. Will start the elimination process tomorrow. And of course I'll keep you all updated.

[haubstr]

I just figured out today why I have gone through 4 batteries in 4 months on my 521. When I put on my used Grant wheel and hooked up the horn I didn't realize that 1 of the wires from the button was grounding out causing the horn relay to be on all the time. I didn't have the horns under the hood hooked up so I didn't know it was on. Today I was taking off the negetive cable to test for a drain and I kept hearing something clicking on and off under the hood. That's when I figured this mess out.

 

On to the next problem

[Draker]

Glad you got it figured out! Thanks for following up with us, it'll help out the next guy.

[Southern Rebel]

I own a 1979 Datsun 210 with a 1.4L and auto trans. My issue is my brake lights stay on and replaced the the switch but it arcs when i connect the wires to the switch any ideas? i'm stumped

[datzenmike]

There will be a small spark because the brake switch is still closed or ON.

 

With the brake peddle down (being used) the switch is closed. Only when the peddle is released does it come up against the switch and a rubber? stop opens the switch. The stop has likely fallen off the peddle. Take a look under the dash at the brake peddle and you'll see what I mean. You may simply have to adjust the stop up more to make the switch open.